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Apparatus, system and method for measuring the properties of a

1. plastic rubber cork glue or another material to create a snug fit between the second threaded PVC plug 433b and the second sheath 405d This snug fit for example may fix the second sheath 405d in place with respect to the second sensor housing 4105 In one embodiment the second seal 4205 may for example comprise a PVC waterproof wire nut Because the second sheath 4054 may comprise or enclose a suspension cable that suspends the second sensor 408b the second sheath 4055 may be used in conjunction with the first sheath 405a and the first and second sensor housings 410a 4106 to space the first and second sensors 408a 408b at a substantially known distance or even a substantially known vertical dis tance US 8 794 061 B1 13 Although the first sensor housing 410a and second sensor 4105 may have substantially similar components and other wise be similarly configured the sensor housings 410a 4105 may also have different components and be otherwise differ ently configured for example pipe 429 may be cut to differ ent lengths and may slide completely through a cross fitting and a T fitting rather than being attached to opposite ends of the cross fitting and T fitting In the embodiment of the sensor assembly 400 shown in FIG 4B the flotation devices 404a 4045 that support the sensor housings 410a 4105 are symmetrical From front to back the flotation devices 404a 404b comprise an end cap 424 a pipe 425 and an end cap 42
2. component requiring power may have its own power supply Likewise where feasible a single line of electronic commu nication for example a power chord with multiple outlets may be replaced by multiple power chords and vice versa One embodiment of a sensor assembly according to the invention will now be described with reference to FIG 4A A sensor assembly 400 comprises a flotation device 404 which may for example be a buoy The flotation device 404 is attached to a sensor housing 410 The sensor housing 410 houses two sensors 408a 4085 separated by a known vertical distance D The two sensors comprise a first sensor 408a at first height h1 and a second sensor 408d at a second height h2 The known vertical distance D represents the vertical com ponent of the distance between the sensors 408a 408b The vertical distance D can be calculated by subtracting the first height h1 from the second height h2 The sensor housing 410 has at least one opening that permits the sensors 408a 408b to be in fluid communication with a liquid if the sensor housing 410 is submerged in the liquid For example if the floatation device 404 is floating on the surface of liquid the sensors 408a 408b will both be submerged at different depths in the liquid corresponding to the first height hl and second height h2 respectively Because the sensors 408a 408b are at dif ferent depths in the liquid the first sensor 408a will measure a first pressure that is hig
3. heights of the at least two sensors Each of the at least two sensors may comprise a stainless steel body that houses a sensor element that comprises a ceramic material The sen sors may comprise for example VEGAWELL 52 pressure transmitters with suspension cables The VEGAWELL 52 pressure transmitter can be obtained from VEGA Grieshaber KG Am Hohenstein 113 77761 Schiltach Germany AVEGAWELL 52 pressure transmitter comprises a sensor element made from dry ceramic capacitive CERTEC and a base element and diaphragm made from high purity sapphire Ceramic A sensor for example a sensor comprising a VEG AWELL 52 pressure transmitter comprises a pressure sens ing facing As used herein a facing is a surface that contacts the liquid The pressure sensing facing may comprise for example a diaphragm Without wishing to be bound by theory it is believed that via the diaphragm a liquid s hydro static pressure causes a capacitance change in a measuring cell in the VEGAWELL 52 The capacitance change is then converted into an appropriate output signal for example a current signal In the VEGAWELL 52 the entire measuring cell consists of high purity ceramic In addition to having excellent long term stability the measuring cell also has very high overload resistance Because the sensor element is a fluid contacting element for example through the pressure sensing facing the sensor element of the sensor is subject to contact with the l
4. the sensors may also have different lines of electronic communication and be otherwise differently configured for example by including different sizes shapes materials and components In FIG 4B the sensor assembly 400 comprises two flota tion devices 404a 404b attached to sensor housings 410a 410b The two flotation devices 404a 4046 comprise a first flotation device 404a and a second flotation device 404b The two sensor housings 410a 4105 comprise a first sensor housing 410a which supports a first sensor 408a at a first height hl and a second sensor housing 4105 which support a second sensor 408b at a second height h2 The first and second sensors 408a 4085 are pressure sensors in the sense that they are able to measure at least a fluid s pressure When the sensor assembly 400 is being used to obtain a density measurement of a fluid the sensor housings 410a 410b are at least partially submerged in the fluid so that the first sensor 408a is sub merged to a first depth in the fluid corresponding to the first height hl and the second sensor 408b is submerged to a second depth in the fluid corresponding to the second height 20 25 30 35 40 45 50 55 60 65 12 h2 Then the first pressure sensor will measure a first pressure measurement corresponding to the fluid pressure at the first height h1 and the second sensor 4085 will measure a second pressure measurement corresponding to the fluid pressure at
5. The sensor assembly 310 is in electronic communication with an MCB 306 through a line of electronic communication 308 between the sensor assembly 310 and the MCB 306 In one embodiment the MCB 306 may be a computational device In one embodiment the MCB 306 may comprise at least a device capable of performing a data conversion step in which a liquid s density is calculated using a constant coef ficient corresponding to a known vertical distance and also using two pressure measurements from at least two pressure sensors in the liquid that are separated by the known vertical distance In another embodiment the MCB 306 may com prise at least a device capable of performing a data conversion step in which a liquid s density is calculated using the at least two pressures corresponding to at least two different depths in the liquid the known vertical distance corresponding to the heights of the at least two sensors and a gravitational accel eration constant Without wishing to be bound by theory the gravitational acceleration constant is approximately equal to the gravitational acceleration of an object caused by earth s gravitational field The gravitational acceleration constant is expressed in appropriate units of measurement for example approximately 9 80665 m s or 32 174 ft s However the value used for the gravitational acceleration constant varies depending on the units of measurement used for the at least two pressures and the know
6. a diaphragm that breaks rather than dents is that breakage will result in a pressure reading that indicates breakage has occurred In contrast if a metal diaphragm dents it may result in an incorrect pressure reading but it will not necessarily be clear that the diaphragm has been damaged or that the pressure reading is incorrect Besides ceramic materials polymers or other materials with one or more desirable characteristics may be used in a sensor element or the pressure sensing facing For example desirable characters include but are not limited to being resis tant to a harsh environment durable measurably flexible hard tending to break rather than dent capable of being used as a measuring cell capable of being used as a capacitor capable of being used in conjunction with a measuring cell and capable of being used in conjunction with a capacitor In one embodiment of the invention the MCB comprises a programmable logic controller PLC and a computer The programmable logical controller comprises a CPU module such as part number CO 00DD1 D available from Automa tiondirect com 3505 Hutchinson Road Cumming Ga 30040 For example the CO OODD1 D comprises a CPU with eight 24 VDC sink source inputs and two isolated commons six 5 to27 VDC sinking outputs with 0 1 A pt and two isolated commons 8K steps of total program memory Ladder Logic programming a built in RS232C programming port an addi tional RS232C Modbus RTu ASCII c
7. on wheels The apparatus the system or any constituent components may be portable Accordingly the invention may comprise handles sleds or wheels The invention may also be light weight For example one embodi ment of the invention comprises a unit including probes that weighs less than 95 pounds Additionally the invention may be compact For example one embodiment of the invention comprises a unit that occupies less than 10 square feet In another example an embodiment of the invention comprises asensor assembly that occupies less than 10 square feet In yet another example the invention comprises a monitor control box sensor assembly and power supply and occupies less than 10 square feet of space Due to its compact size and light weight one embodiment of the invention can be flown to remote locations by light aircraft or shipped at low costs In another embodiment of the invention all components are weather proof and sensors are durable enough to with stand the demands of an oil drilling site For example in one embodiment of the invention the sensors are mud probes made from durable materials In another embodiment the sensors are made from the toughest industrial materials avail able In another embodiment the sensors comprise ceramic and stainless steel components In one embodiment the sen sors comprise VEGAWELL 52 pressure transmitters with suspension cables For example a VEGAWELL 52 pressure transmitter comprises a
8. tilted As another alternative it may be desirable to convert pressure readings from the sensors into information regarding the depth of the sensors in a liquid by using a recently calculated density of the liquid The information regarding the depth of the sensors could then be used to calculate an estimated angle of tilt by employing trigonometry In calculating an estimated angle of tilt it may be useful include one or more additional sensors at a fixed distance from one of the two sensors and not in line with the two sensors For example next to a first set of two sensors a second set of two sensors may be fixed a known distance from the first set of two sensors The pressure readings may then be converted to liquid depths at each sensor using recently esti mated densities The liquid depths at each sensor may then be used to obtain an angle of tilt Other approaches for obtaining an exact or approximate angle of tilt could also be employed It is desirable that the at least one opening in the sensor housing 410 permits sufficient fluid communication between the sensors 408a 408b and the liquid so that the properties of the liquid in contact with the sensors inside the sensor housing 410 are substantially similar to the properties of the liquid outside the sensor housing 410 even if for example the composition and the properties of the liquid are constantly changing This will help to ensure that the properties of the liquid inside the sen
9. woe 73 152 27 11 2013 Singfield 11 2013 Singfield 2013 0298696 Al 11 2013 Singfield 2014 0007668 A1 1 2014 Shanks wu 73 152 51 OTHER PUBLICATIONS Vega Process pressure Hydrostatic Operating instructions 35401 EN 111021 from www vega com downloads BA 35401 EN VegaWell PDF The Mud Watcher Transforming Mud Monitoring Specifications from www mudautomatics com Red Lion G306 from www redlion net Products HumanMachinelnterface OperatorInterface G306 html Denver Smart et al Micro Motion White Paper Emerson Process Management Micro Motion WP 001243 Rev B 2013 from www2 emersonprocess com en US brands micromotion industries oil and gas oilfield services drilling fluids management Pages Index aspx Auto Wate Drilling Solutions screen shot from www autowate com Click Koyo Click CPUs C0 00DD1 D CPU from www aboutples com click Hardware CPU Modules c0 00dd1 d html Emerson Process Management Oilfield Services from www2 emersonprocess com en US brands micromotion industries oil and gas oilfield services drilling fluidsmanagement Pages Index aspx MudAutomatics screen shot from www mudautomatics com The Mud Weight Watcher Transforming Weight Control from www mudautomatics com Vega Vegawell 52 Specification Sheet 34734 EN 09 10008 from www vega com downloads BA 34734 EN Well52SpecificationSheet PDF Vega Vegawell 52 Operating Instructions 4 20 mA HART Pt 100 35402 EN 111021 Documen
10. 4 Although the flotation devices 404a 404b may have substantially similar compo nents and otherwise be similarly configured the flotation devices 404a 4045 may also have different components and be otherwise differently configured In the embodiment of the sensor assembly 400 shown in FIG 4B the first sensor housing 410a is in front of the second sensor housing 410b Because both sensor housings 410a 410b are oriented substantially vertically they are also ori ented substantially parallel The first sensor housing 410a is secured in a substantially parallel orientation to the second sensor housing 4105 by three configurations of PVC piping and fittings Beginning with the left side of the first sensor housing 410a as shown in FIG 4B the first configuration 435a of PVC piping and fittings comprises from front to back the first cross fitting 427a on the first sensor housing 410a pipe 434 a 90 degree elbow 432 pipe 434 a 90 degree elbow 432 pipe 434 and the second cross fitting 427b on the second sensor housing 4105 The second configuration 4355 of PVC piping and fittings forms a mirror image of the first configuration 435a of PVC piping and fittings and occurs on the opposite side of the sensor housings 410a 4105 Begin ning with the right side of the first sensor housing 410a as shown in FIG 4B the second configuration 435b of PVC piping and fittings comprises from front to back the first cross fitting 427a on the first sens
11. 712 138 B2 3 2004 Mandal 7 735 378 B2 6 2010 Singfield et al 2004 0200287 A1 10 2004 Mueller et al oe 73 715 2009 0056422 A1 3 2009 Ouinn et al 73 53 01 2009 0285721 Al 11 2009 DeGreeve et al 2012 0097388 A1 4 2012 Beck nesses 166 250 07 2012 0193090 A1 8 2012 Lopez De Cardenas 166 250 01 Continued FOREIGN PATENT DOCUMENTS WO 2012000044 Al 1 2012 WO 2012061872 Al 5 2012 OTHER PUBLICATIONS Vega Process pressure Hydrostatic Pressure measurement 35400 EN 090130 from www vega com downloads BA 35400 EN Vegawell52ProductInformation PDF Continued Primary Examiner John Fitzgerald Assistant Examiner Marrit Eyassu 74 Attorney Agent or Firm Colin P Cahoon Brandon V Zuniga Carstens amp Cahoon LLP 57 ABSTRACT An apparatus and method used to determine the density and other properties of a corrosive liquid such as drilling mud The apparatus uses at least two sensor elements with ceramic facings spaced a known vertical distance apart and inserted into the fluid The differential pressure measurement pro vided by these sensors is used to calculate the density of the liquid This density measurement is then reported in real time to an operator 14 Claims 5 Drawing Sheets MONITOR l CONTROL BOX I US 8 794 061 B1 Page 2 56 References Cited U S PATENT DOCUMENTS 2012 0204636 Al 2013 0199286 Al 2013 0291620 Al 2013 0298663 Al 8 2012 Teli etal woe 73 309 8 2013 Gao etal
12. a known vertical distance The corrosive liquid may be erosive abrasive fouling caustic basic acidic capable of damaging sensors or any possible combination thereof The corrosion resistant sensors may be constructed for example from sensor elements that comprise ceramic components The invention further provides for optionally measuring one or more other liquid properties for example viscosity pH salinity chloride content and H2S concentra tion The invention further provides for conducting other types of analysis such as measuring physical or chemical properties In a first aspect the invention provides an apparatus that can measure a corrosive liquid s density by using at least two corrosion resistant pressure sensors submerged in the corro sive liquid and separated by a known vertical distance to obtain at least two pressures at different depths in the corro sive liquid In a second aspect the invention provides a system com prising a power supply a Monitor Control Box MCB and at least two corrosion resistant pressure sensors that are spaced a known vertical distance apart in a sensor housing and are in electronic communication with the power supply and the MCB In a third aspect the invention provides a method compris ing the steps of pooling a corrosive liquid inserting into the liquid an apparatus comprising at least two corrosion resistant pressure sensors that are separated by a known distance using the at l
13. ally similar compo nents ofa given type such as a pipe or different kinds of pipe for example pipe made from different materials The inventor expects variations in the configuration of the sensor assembly r 5 20 30 40 45 50 55 14 400 including but not limited to variations in size shape materials and constituent components As another example the sensor assembly may not even include a sensor housing For example the sensors may be directly suspended in a fluid and separated by a known vertical distance by using suspen sion cables As another example the suspension cables may be tied together so that the sensors may be suspended ina fluid and separated by a known vertical distance One embodiment of a sensor housing according to the invention will now be described with reference to FIG 4C A sensor housing 410 comprises from top to bottom a top end cap 451 a PVC pipe 429 and a bottom end cap 431 The end caps may be used to help hold two pressure sensors 408a 4085 in place The PVC pipe 429 comprises holes 450 As in FIG 4A and unlike FIG 4B the two pressure sensors 408a 408d in FIG 4C are both in a single sensor housing 410 Ifthe sensor housing 410 is submerged in a liquid the holes 450 allow the two pressure sensors 408a 408b inside the sensor housing 410 to be in fluid communication with the liguid The two pressure sensors 4084 4085 comprise a first pressure sensor 408a and a second pressure se
14. az United States Patent Sickels Jr US008794061B1 US 8 794 061 B1 Aug 5 2014 10 Patent No 45 Date of Patent 54 71 72 73 C 21 22 63 51 52 58 APPARATUS SYSTEM AND METHOD FOR MEASURING THE PROPERTIES OF A CORROSIVE LIQUID Applicant Ultra Analytical Group LLC League City TX US Inventor Robert Eugene Sickels Jr Mansfield TX US Assignee Ultra Analytical Group LLC League City TX US Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 0 days Appl No 14 096 444 Filed Dec 4 2013 Related U S Application Data Continuation of application No 14 046 118 filed on Oct 4 2013 Int Cl E21B 49 00 2006 01 GOIN 9 26 2006 01 US Cl CPC GOIN 9 26 2013 01 USPC ie at ooo Gisinvosavesnaaseres 73 152 05 73 451 Field of Classification Search CPC GOIN 17 008 GOIN 17 04 GOIN 2009 26 GOIN 2009 63 GOIN 9 00 GOIN 9 36 GOIN 9 26 GOIN 9 32 GOIN 9 12 GOIN 9 18 GOIN 9 10 USPC ernati ots 702 9 73 32 R 454 See application file for complete search history I POWER l SUPPLY l I 4 400 56 References Cited U S PATENT DOCUMENTS 4 916 426 A 4 1990 Yajima et al 338 4 5 325 716 A 7 1994 Hafner et al 73 301 6 378 362 B1 4 2002 Dickinson wee 73 152 28 6 687 643 B1 2 2004 Cason Jr wee 702 137 6
15. cal component of the distance between the two sensors 408a 4085 For example if the distance from the first sensor to the second sensor is repre sented as a vector from the first sensor to the second sensor and that vector is resolved into a z component that is parallel but opposite to the direction of gravitational acceleration and an X component and a y component that are perpendicular to each other and the z component then the z component will be the vertical component of the distance between the two sen sors 408a 408b Because the actual distance between the two sensors 408a 4085 will remain constant but the vertical com ponent of this distance will change when the flotation device tilts it may be desirable to employ one or more devices to ensure that the surface of the liquid remains calm and level Furthermore it may be desirable to employ a flotation device 404 with a longer radius length or width as applicable to the shape of the flotation device 404 Doing so will help to decrease the tilt that the flotation device 404 experiences when floating over a disturbance in the surface of the liquid Likewise it may be desirable to employ a gyroscope to pre vent tilt Alternatively it may be desirable to measure the angle of tilt of the sensors for example by using a gyroscope so that the known vertical distance D can be calculated from the measured angle of tilt and the vertical distance between the sensors when the sensors are not
16. cal distance between the first and second height is 2 feet However if the known vertical distance D changes the coefficient would need to be recalculated accordingly Without wishing to be bound by theory it is also useful to note that the known vertical distance D is only equal to the actual distance between the two sensors 408a 4085 when the sensors 408a 408b are oriented along a line that is parallel to the direction of acceleration caused by gravity If the surface of the liquid is calm and level then the surface of the liquid will be perpendicular to the direction of acceleration caused by gravity Accordingly if the surface of the liquid is calm and level the flotation device 404 is floating parallel to the surface of the liquid the sensor housing 410 is attached to the flota tion device 404 so that the sensor housing 410 is oriented perpendicular to the surface of the liquid and the sensors 408a 408b are oriented along a line that is parallel to the US 8 794 061 B1 9 sensor housing 410 then the known vertical distance D will be equal to the actual distance between the two sensors 408a 4085 However if the surface of the liquid is disturbed for example by waves and the flotation device 404 tilts so that it is no longer perpendicular to the direction of acceleration caused by gravity then the known vertical distance D will no longer be the actual distance between the two sensors 408a 408b Instead it will be the verti
17. e for the additional safety reliability and efficiency it can provide Although some existing devices such as Coriolis and Ven turi flowmeters can provide real time density data they have proven unreliable when operating under the corrosive ero sive abrasive fouling caustic basic acidic or other harsh conditions imposed by drilling fluids Drilling mud is typi cally made up of water clay and additives used to modify the mud s viscosity density pH and other properties The mud creates an environment that is not conducive to prior art sensors For example the mud contains solids including solids in the mud and well cuttings that can be abrasive or erosive These solids can scrape a sensor and damage it The mud also tends to be basic which can damage a sensor by eating away at the sensor Additionally the mud can form layers on a surface that are difficult to remove If the mud forms layers on the sensor the sensor may become fouled and fail to work properly What is needed is a new and innovative device capable of autonomously transmitting real time density data even under the harsh conditions involved in drilling For example a need exists for an apparatus that can measure the density of mud or other liquids every second of every minute during the drilling process and then transmit the measured data to provide opera tors with density data that is extremely accurate Accordingly the risks and liability associated with drilli
18. eal time the density of a drilling mud said system comprising a sensor assembly a power supply in electronic communication with said sensor assembly a computational device in electronic communication with said sensor assem bly a user interface in electronic communication with said computational device wherein said sensor assembly houses at least two corrosion resistant pressure sensors and wherein further each pressure sensor is located in a fixed location on the sensor assembly providing a known vertical distance between the two sensors In another embodiment the pres sure sensors comprise a ceramic facing In another embodi ment the computational device comprises a computer In another embodiment the computer comprises a CPU In another embodiment the computational device further com prises a programmable logic controller in electronic commu nication with the at least two sensors and the computer In another embodiment the power supply comprises a battery box in electronic communication witha solar panel In another embodiment the battery box comprises a power con verter and a battery wherein further the power converter is in electronic communication with the battery the solar panel the computer and the programmable logic controller In another embodiment the at least two sensors are in wireless communication with the programmable logic con troller In another embodiment the computational device com prises a wireless c
19. east two pressure sensors to detect at least two pres sures of the liquid corresponding to a minimum of two dif ferent liquid depths that are separated by the known distance transmitting data comprising the at least two different pres sures to a device capable of converting the pressure data to a density using the device to convert the at least two different pressures into a density for the corrosive liquid and transmit ting a result comprising at least the density for the corrosive liquid The inventor has developed a new and innovative device capable of autonomously transmitting real time density data even under the harsh conditions involved in drilling For example one embodiment of the invention can measure the density of mud or other liquids every second of every minute during the drilling process and then transmit the measured data to provide operators with density data that is extremely accurate Accordingly the risks and liability associated with drilling wells may be reduced while the reliability and effi ciency of the drilling process are simultaneously increased For example there is no longer a need to call out mud weight over intercoms Instead operators may receive real time read outs of mud density and have peace of mind that a drilling fluid is operating within a safe density range Another benefit of the invention is that one embodiment is highly energy efficient using for example only about 24 watts of power As a re
20. easured by the second sensor 4085 may be transmitted to the MCB through the sensors respective lines of electronic communication with the MCB In FIG 4B a first sheath 405a and a second sheath 4055 comprise two sheaths Sheath 405a may enclose at least one suspension cable the line of electronic communication between the first sensor 408a and the monitor control box the line of electronic communication between the first sensor 408a and the power supply and a first tube between the first sensor and atmosphere The first tube can be used by the first sensor 408a for example to provide atmospheric pressure to the first sensor 408a Atmospheric pressure can be used to obtain a gauge pressure measurement although the sensors 408a 4085 may also be set up to provide an absolute pressure measurement Alternatively the sheath 405a may comprise a suspension cable Like sheath 405a sheath 4055 may enclose at least one suspension cable the line of electronic commu nication between the second sensor 4085 and the monitor control box the line of electronic communication between the second sensor 4085 and the power supply and a second tube between the second sensor and atmosphere The second tube can be used by the second sensor for example to provide atmospheric pressure to the second sensor Although the first sensor 408a and second sensor 4085 can have substantially similar lines of electronic communication and otherwise be similarly configured
21. ent the invention comprises an apparatus or system that can measure density accurately to 0 0001 pounds per gallon and includes a device capable of visually displaying density measurements with a one s digit and five decimal places for example 0 00000 if desired For example in one embodiment the pressure transmitters are so sensitive that they can detect a pressure change in air due to wind or due to being blown on by a person In one embodi ment the apparatus or system provides real time read outs of density measurements while the apparatus or system is in situ Accordingly this eliminates the need for calling out mud weight over intercoms In one embodiment the invention comprises an electronic device for determining the density of drilling mud The device comprises two transducers submerged in a liquid at a fixed vertical distance apart The device provides a digital read out oftwo pressures measured by the two transducers The device uses an algorithm to calculate the difference in pressure detected at the two transducers The result of the calculation is then shown in a digital read out The device calculates the difference in pressures approximately 10 times per second The difference in pressure is then used in combination with the fixed vertical distance to calculate the density of the liquid The device digitally displays the density The device calculates the difference in pressures approximately 10 times per second In
22. ents are convertible to a density measure ment of the drilling mud 4 The system of claim 1 wherein the at least two pressure sensors are housed in two separate sensor housings 5 The system of claim 1 wherein the system further com prises at least one redundant pressure sensor 6 The system of claim 1 further comprising a sensor for measuring a physical or chemical property of the drilling mud 7 The system of claim 1 wherein the system further com prises at least one additional sensor for measuring a fluid property selected from the group consisting of pH viscosity salinity chloride content and temperature 8 The system of claim 1 further comprising a power supply 9 The system of claim 1 further comprising an electronic communication with a device to convert raw data provided by the sensors 10 The system of claim 1 wherein the rigid body com prises plastic pipe 11 The system of claim 10 wherein the rigid body com prises PVC pipe 12 The system of claim 1 wherein the rigid body com prises welded metal pipe 13 The system of claim 12 wherein the rigid body com prises stainless steel pipe 14 The system of claim 1 wherein the pressure sensors comprise a stainless steel casing E
23. ers buttons dials a com puter a cellular device a portable digital assistant a smart phone or a device that uses audio visual tactile or electronic signals for communication with a user A user may comprise at least one person or device For example a user may be a drilling operator who uses a user interface to monitor a drilling mud s density A user may also be a computer portable device smart phone information storage device a system a network or remote corporate offices One embodiment of a system according to the invention will now be described with reference to FIG 3 A power supply 314 is in electronic communication with a sensor assembly 310 and a monitor control box 306 through lines of electronic communication 312 between the power supply 314 0 r 5 20 30 40 45 50 55 6 and the sensor assembly 310 and between the power supply 314 and the MCB 306 The sensor assembly 310 is also in electronic communication with an MCB 306 through a line of electronic communication 308 between the sensor assembly 310 and the MCB 306 The MCB 306 is in electronic com munication with a user interface 302 through a line of elec tronic communication 304 between the MCB 306 and the user interface 302 Generally speaking the user interface permits communication between a user and the invention For example the user interface 302 may comprise a minimum of one device capable of at least receiving informatio
24. example a computer may be a laptop or a desktop computer a smart phone a personal digital assistant PDA or other device with various configurations US 8 794 061 B1 17 In one embodiment the invention comprises a single sen sor housing that houses at least two pressure sensors sepa rated by a known vertical distance In another embodiment each of the at least two pressure sensors separated by a known vertical distance may be housed in a separate sensor housing In addition to pressure sensors one or more sensor housings may house other sensors Generally speaking a sensor hous ing may substantially or partially contain sensors protect sensors and maintain two pressure sensors at a fixed distance relative to each other However a device as simple as a rigid body of sufficient length may also be used to maintain the sensors at a fixed relative distance For example the fixed relative distance may be 12 inches or 24 inches However different lengths may also be used For example the lengths may be less than 12 inches between 12 inches and 24 inches or greater than 24 inches Several factors influence the length for example a minimum known vertical distance necessary between at least two pressure sensors to obtain reliable den sity measurements for a liquid and a maximum known ver tical distance between the at least two pressure sensors such that the pressure sensors may all be submerged in the liquid In one embodim
25. for the in situ apparatus or system to continuously measure record and transmit density pressures As another example after setting up an apparatus or system comprising its own power supply no additional actions are reguired for the in situ apparatus or system to continuously measure record and transmit density pressures As another example after setting up an apparatus or system in situ no additional actions apart from maintenance for example calibrating cleaning repair ing or replacing a component are reguired for the in situ apparatus or system to substantially continuously measure record and transmit density pressures In one embodiment the invention comprises an apparatus or system that reguires no supply of external power For example the invention may use solar power or batteries or fuel cells or any combination thereof In one embodiment the apparatus or system can operate for 24 hours without a solar charge This permits the invention to be operated for example without needing to provide a separate source of power at a drill site This is feasible in part because the apparatus or system reguires little power for example using approximately 24 Watts of power or less The embodiment may also comprise back up batteries that can for example power the invention for 36 hours In another embodiment the invention comprises an appa ratus or system that is portable for example capable of being carried slid or rolled
26. he user interface is remote from the device of step d In another embodiment the user interface is a cellular device I claim 1 A system for measuring in situ the density of a drilling mud in combination with a drilling well mud tank said sys tem comprising at least two corrosion resistant pressure sensors separated by a known vertical distance on the system wherein the at least two pressure sensors comprise corro sion resistant fluid contacting parts comprising a pres sure sensing facing said pressure sensing facing com prising a ceramic material wherein the at least two pressure sensors are fixed to at least one rigid body said rigid body comprising a float that floats on the surface of the drilling mud in the drilling well mud tank and at least one sensor housing attached to said float such that when the system is in situ the sensor housing is submerged in the drilling mud below the float and wherein said sensor housing contains said at least two sensors spaced a vertical distance apart in the housing such that each sensor occupies a different vertical posi tion in the drilling mud when the system is in situ 20 25 30 2 2 The system of claim 1 wherein the ceramic material is a high purity sapphire ceramic material 3 The system of claim 1 wherein the system comprises a communication device for transmitting in situ real time continuous pressure measurements from the sensors which pressure measurem
27. her than a second pressure measured by the second sensor 408b These pressures can then be used in conjunction with the known vertical distance D to calculate the density of the liquid For example without wishing to be bound by theory a liquid s density can generally be calcu lated as equal to the difference in the first and second pres sures divided by the product of gravitational acceleration times the known vertical distance D In performing this cal culation consistent units of measurement must be used Alternatively if the known vertical distance D is constant then the calculation can essentially be reduced to calculating a liquid s density by using conversion factors consolidated in the form of a constant coefficient that converts the difference in the first and second pressure to a density The coefficient is dependent on the known vertical distance D but not on a particular liquid composition For example the coefficient 9 6 is derived from the conversion factors necessary to obtain density in pounds per gallon from pressure readings in psig from a first sensor 408a and a second sensor 4086 separated by a known vertical distance D of 2 feet Accordingly the density of a liquid in pounds per gallon is approximately equal to 9 6 times the difference of the first pressure minus the second pressure where the first and second pressures are given in psig where the mud density is given in pounds per gallon and where the known verti
28. ibed with reference to FIG 4B A sensor assembly 400 comprises two flotation devices 404a 404b attached to sensor housings 410a 410b The two sensor housings 410a 410b comprise a first sensor housing 410a which supports a first sensor 408a at a first height hl and a second sensor housing 4105 which supports a second sensor 408b at a second height h2 Accordingly the two pressure sensors are separated by a known vertical distance D which represents the vertical component of the distance between the first and second sensors The known vertical distance D can be calculated by subtracting the first height h1 from the sec ond height h2 The sensor housings 410a 410b each have at least one opening that permits the pressure sensors to be in fluid communication with a liquid if the sensor housings 410a 4106 are submerged in the liquid For example if floatation devices 404a 4046 are floating on the surface of liquid the first and second sensors 408a 408b will both be submerged at different depths in the liquid corresponding to the first height h1 and second height h2 respectively Because the first and second sensors are at different depths in the liquid the first sensor will measure a first pressure that is higher than a second pressure measured by the second sensor These pressures can then be used in conjunction with the known vertical distance D to calculate the density of the liquid It may be desirable to increase the length of the flota
29. ifferential pressure from sensors separated by the fixed vertical distance The coefficient is equal to the known density divided by the differential pressure After calculating the coefficient the coefficient can be used to calculate a density fora liquid from a differential pressure reading corresponding to sensors separated by a fixed vertical distance in the liquid Although in one embodiment the MCB comprises a PLC and a computational device various configurations of the MCB are possible For example in one embodiment the MCB comprises a device capable of receiving raw data and converting the raw data into a density for a corrosive liquid In another embodiment the MCB may be a computational device Sixth in a transmission of results step 212 the density of the mud is transmitted to a user interface The user interface permits a user to interact with the invention for example to access density calculations or other information The user interface may also permit a user to operate the invention The user interface comprises a minimum of one device capable of at least receiving information from or transmitting informa tion to the MCB The user interface may be co located with the MCB or remote from the MCB Accordingly the user interface may be co located with or remote from a device used to convert the raw data into a density value for the corrosive liquid For example a user interface may comprise a control panel a touchscreen lev
30. iquid For example a diaphragm in a sensor element that comprises a pressure transducer may be in direct contact with the liquid and thus be a fluid contacting part Without wishing to be bound by theory the inventor believes that if the liquid is fouling or corrosive for example abrasive erosive caustic basic or acidic the sensor element can foul or corrode causing the sensor to fail For example if a sensor element comprises a pressure transducer a dia phragm in the pressure transducer may experience unaccept able levels of corrosion if it is not made from a corrosion resistant material Similarly if for example a diaphragm in a pressure transducer is not made from a fouling resistant material the diaphragm may experience unacceptable levels of fouling Furthermore if for example a diaphragm in a pressure transducer is not made from an abrasion resistant or erosion resistant material the diaphragm may experience abrasion or erosion respectively However by using fouling corrosion abrasion and erosion caustic basic pH and acidic pH resistant materials for example dry ceramic ca pacitive CERTEC and high purity sapphire Ceramic for the sensor element a fouling corrosion abrasion and erosion caustic basic pH acidic pH resistant sensor may be obtained Although CERTEC and high purity sapphire Ceramic are examples of a fouling resistant corrosion resistant abra sion resistant erosion resi
31. mation may com prise data regarding a liquid including at least one measured liquid property for example density viscosity pH and chlo ride content The apparatus or system may detect information comprising at least two pressures at two different depths in a liquid The at least two pressures may be obtained by using two sensors In one embodiment the sensors can provide pressures in psi pressures in inches of water column densi ties in pounds per gallon or some combination thereof that are accurate to 0 01 of a respective measurement Addition ally the apparatus or system may include redundant sensors multiple sensors to measure different properties or single sensors that measure multiple properties The information detected by the apparatus or system may be saved by the apparatus or system for example for up to four years In one embodiment of a system according to the invention a power supply is in electronic communication with a sensor assembly and a monitor control box The sensor assembly is also in electronic communication with an MCB The MCB is US 8 794 061 B1 15 optionally in electronic communication with a user interface The user interface comprises a minimum of one device capable of at least receiving information from or transmitting information to the MCB The sensor assembly comprises at least two corrosion resistant pressure sensors spaced apart by a known vertical distance whose end points correspond to the
32. ment the at least two pressure sensors are housed in two separate sensor housings In another embodiment the at least one sensor housing con tains at least one pressure sensor wherein further said sensor housing is attached to said float such that when the apparatus is in situ the sensor housing is submerged in the liquid below the float In another embodiment said sensor housing con tains at least two sensors spaced a vertical distance apart in the housing such that each sensor occupies a different vertical position in the liquid when the apparatus is in situ In another embodiment the apparatus further comprises at least one redundant pressure sensor In another embodiment the apparatus further comprises a sensor for measuring a physical or chemical property of the liquid In another embodiment the apparatus further com prises at least one additional sensor for measuring a fluid property selected from the group consisting of pH viscosity salinity chloride content and temperature In another embodiment the apparatus further comprises a power supply In another embodiment the apparatus further comprises an electronic communication with a device to convert raw data provided by the sensors In another embodiment the rigid body comprises PVC pipe In another embodiment the pressure sensors comprise a stainless steel casing and a ceramic pressure sensing facing One embodiment of the invention is a system for determin ing in r
33. mple a power outlet at a drilling site As another example the power supply 314 may comprise a power outlet and a power converter The power supply 314 may alternatively comprise at least one battery box fuel cell capacitor power generator or other energy storage device The battery box may comprise for example at least one battery Alternatively the battery box may comprise a power converter and at least one battery As another example the power supply 314 may comprise for example a battery box in electronic communication with a solar panel As another example power supply 314 may comprise a power converter in electronic communication with the sensor assembly 310 the MCB 306 at least one battery a solar panel and a com munication device In one embodiment the power converter is in electronic communication with the communication device In another embodiment the battery box may be por table For example the power supply or substituent compo nents may be provided with handles or situated on a sled or wheels In another embodiment the power supplied to the sensor assembly 310 may come from a power supply 314 connected to the MCB 306 For example the power supply 314 may be connected to MCB 306 and power may be trans ferred to sensor assembly 310 by a cable such as a USB cable In one embodiment a single power supply 314 may provide power to the user interface 302 the MCB 306 and the sensor assembly 310 In another embodimen
34. n a data conversion step 210 at the MCB the at least two pressures and the known distance are used to calculate the density of the mud Thus the pressure measurements from the at least two pressure sensors are convertible into a density measurement of a corrosive liquid In one embodiment the at least two pressures from the PLC are transferred to a com puter which uses the known distance to calculate the density of the mud For example the density can be calculated as follows Start by subtracting the pressure at a first sensor from the pressure at a second sensor to obtain a pressure differen tial Then calculate the density by dividing the pressure dif ferential by the product of multiplying a unit of measure ment appropriate gravitational acceleration constant and the known distance Alternatively the density can be calculated by recognizing that given a first pressure sensor at one depth in a liquid a second pressure sensor at another depth in a liquid and a fixed vertical distance between two pressure sensors the differential pressure between the liquid s pres sures at the first and second sensors is proportional to the liquid s density Thus the density of the liquid is equal to some constant coefficient times the differential pressure of the liquid for given units of measurement Using this relation ship the coefficient can be calculated by placing the two pressure sensors in a fluid with a known density and obtain ing a d
35. n from or transmitting information to the MCB 306 and receiving infor mation from or transmitting information to a user The sensor assembly 310 may comprise at least two sen sors For example the sensor assembly 310 comprises at least two corrosion resistant pressure sensors spaced apart by a known vertical distance whose end points correspond to the heights of the at least two sensors The known vertical dis tance only includes the vertical component of a distance between the two sensors but not the horizontal component of the distance between the two sensors The pressure sensors are at least capable of measuring the pressure ofa liquid at two different depths in the liquid The two different depths corre spond to the heights of the at least two sensors and the end points of the known vertical distance In one embodiment the sensor assembly may comprise two pressure sensors in the form of pressure transmitters with suspension cables The suspension cables may be fixed rela tive to each other so that as they suspend the pressure trans mitters the pressure transmitters are also separated by a sub stantially fixed distance In another embodiment the sensor assembly may comprise at least one sensor housing In another embodiment the sensor assembly may comprise two sensor housings wherein the sensor housings both house a separate sensor The sensor assembly may also comprise other sensors or sensor housings in various configurations
36. n vertical distance In one embodiment the MCB 306 may comprise a pro grammable logic controller PLC a computational device such as a computer and a communication device In another embodiment the computer may comprise the communication device The communication device may be a wired or wire less communication device The communication device may US 8 794 061 B1 7 comprise for example a device capable of transmitting or receiving information using wired connections cable optical fiber wireless connections radio WiFi or Bluetooth The communication device may be in electronic communication with at least one user interface 302 The communication device may be in electronic communication with at least one user through the user interface 302 The user may comprise for example a human a device a computer a system or a network The PLC may be in electronic communication with the at least two sensors For example the PLC may be in wired or wireless communication with the at least two sen sors The sensor assembly 310 is also in electronic communica tion with the power supply 314 through a line of electronic communication 312 between the sensor assembly 310 and the power supply 314 In the embodiment illustrated in FIG 3 the power supply 314 comprises at least a device capable of providing the necessary level of power to the sensor assembly 310 and the MCB 306 For example the power supply 314 may comprise for exa
37. ng mud is use ful for controlling well formation pressures removing well cuttings and facilitating the cementing and completion of wells Perhaps one of the most important functions of drilling muds is to help to prevent potentially devastating oil well blowouts However drilling muds are only effective at pre venting blowouts when their properties such as density are properly adjusted Real time measurement of drilling prop erties is also used to help the rig operator understand down hole conditions Consequently being able to measure the properties of these fluids while a well is being drilled is critical Up until now traditional mud scales or balances have been used to measure the density weight of drilling fluid cement or any other type of liquid or slurry Typically the mud scales on a drilling site consist of a graduated beam with a bubble level a weight slider along its length and a cup with a lid on the end The cup is used to hold a set amount of liquid to be weighed The slider weight can be moved along the beam and a bubble indicates when the beam is level Density is read at the point where the slider weight sits on the beam at level Mud scales are calibrated by using a liquid of known den sity often water and adjusting a counter weight Generally the scales are not pressurized but a pressurized mud scale operates in the same manner A method for employing a traditional mud scale will now be described with refe
38. ng wells could then be reduced while the reliability and efficiency of the drilling process is simultaneously increased For example there would no longer be a need to call out mud weight over intercoms Instead operators could receive real time read outs of mud density and have peace of mind that a drilling fluid is operating within a safe density range It would also be beneficial if such apparatus were highly energy efficient using for example using only 24 watts of power As a result the embodiment can run off of back up battery power for long periods between charging by a solar charge This is desirable for both environmental benefits and cost savings It would also be beneficial if such apparatus were highly portable comprising a light weight compact unit Such a unit could be flown to remote locations by light aircraft or shipped at low costs due to its compact size and light weight Furthermore if the unit were constructed from weather proof components and the mud probes were made from highly durable industrial materials the unit would be capable of standing up to the rigorous conditions encountered at many drilling sites SUMMARY OF THE INVENTION The present invention generally provides for an apparatus system and method for measuring at least the density of a US 8 794 061 B1 3 corrosive liquid for example a drilling mud by using at least two submerged corrosion resistant pressure sensors that are separated by
39. not limited to a central processing unit CPU a program mable logic controller PLC and a computer Alternatively the MCB may comprise for example a PLC and a computa tional device During the transmission of raw data step 208 the raw data is transferred by electronic communication for example by wired communication wireless communication radio WiFi Bluetooth cable or optical fiber In one embodi ment the raw data may be transferred from the sensors to the PLC For example the raw data corresponding to pressure measurements may be transferred in a signal Furthermore the signal may comprise an electrical current In one embodi ment a current of 4 milliAmps mA may correspond to a pressure measurement of 0 psi while a current of 20 mA may correspond to a pressure measurement of 36 26 psi Currents between 4 mA and 20 mA may correspond to pressure mea surements between 0 psi and 36 26 psi In one embodiment the PLC converts the raw data from the sensors into pressures For example the PLC converts a 20 mA signal into a pressure of 36 26 psi and a 0 mA signal into a pressure of 0 psi Although the correlation between the pressures and currents may be different Likewise the form of electronic communi US 8 794 061 B1 5 cation used can vary For example in another embodiment the MBC may comprise a computational device in electronic communication with a sensor assembly and a user interface Fifth i
40. nsor 408b The first pressure sensor 408a may transmit and receive electronic communication through a first cable 452a The second pres sure sensor 408b may transmit and receive electronic com munication through a second cable 4525 The first and second cables 451a 451b extend through a hole in the top of end cap 451 COMPARATIVE EXAMPLES In one embodiment the invention comprises an apparatus or system that can measure at least one of a fluid s properties to a desired accuracy For example the fluid may comprise a liquid a mud a cement a slurry or a solution In another embodiment the invention comprises an appa ratus or system that detects records and reports information to at least one user In one embodiment the apparatus con tinuously detects records and reports information although in another embodiment the apparatus performs these opera tions intermittently The information may be collected by at least one sensor The information may comprise data regard ing a physical or chemical property of a liquid Examples of physical properties include but are not limited to absorption boiling point capacitance color concentration density elec trical conductivity melting point solubility specific heat temperature thermal conductivity viscosity and volume Examples of chemical properties include but are not limited to chemical stability enthalpy of formation flammability heat of combustion and toxicity The infor
41. ntinuation of and claims filing pri ority rights with respect to currently pending U S patent application Ser No 14 046 118 filed on Oct 4 2013 BACKGROUND OF THE INVENTION 1 Technical Field The present invention generally relates to measuring at least the density of a corrosive liquid by using at least two submerged corrosion resistant pressure sensors that are sepa rated by a known vertical distance The corrosive liquid may be erosive abrasive fouling caustic basic acidic capable of damaging sensors or any possible combination thereof In particular the invention relates to an apparatus system and method for measuring the density of a corrosive liquid such as drilling mud by using at least two corrosion resistant pressure sensors submerged in the corrosive liquid and sepa rated by a known vertical distance to obtain at least two pressures at different depths in the corrosive liquid 2 Background With the discovery of new drilling techniques such as hydraulic fracturing the United States is currently experienc ing an energy bonanza In addition to the wells being drilled with new techniques many more wells are being drilled with tried and true techniques All told thousands of wells are being drilled every year in the United States alone In every one of these wells drilling fluids such as muds cements or other slurries play an integral role in ensuring a safe and efficient drilling operation For example drilli
42. ommunication device in electronic com munication with the user interface In another embodiment the user interface is a cellular device One embodiment of the invention is a method for measur ing physical properties including at least the density of a corrosive liquid such as drilling mud said method compris ing the steps of a pooling a corrosive liquid b inserting into the liquid an apparatus comprising at least two corrosion resistant pressure sensors that are separated by a known ver tical distance on the apparatus c detecting a reading from each of two said sensors corresponding to the pressure expe rienced by each sensor while in the liquid said reading com prising raw data provided by each sensor d transmitting said US 8 794 061 B1 21 raw data to a device e using the device to convert the raw data into a density value for the corrosive liquid and f trans mitting said density value to a user interface In another embodiment additional sensors are used at step b In another embodiment said additional sensors detect raw data used in step c related to the pH of the liquid In another embodiment said additional sensors detect raw data used in step c related to the viscosity of the liquid In another embodiment said additional sensors detect raw data used in step c related to the salinity of the liquid In another embodiment the user interface is co located with the device of step d In another embodiment t
43. ommunications port that can be configured up to 115200 baud a removable ter minal block and replacement Analogue to Digital Converter ADC part number CO 16TB However a PLC may com prise other components and employ other configurations as well For example a PLC may have a different CPU a dif ferent number voltage current or type of outputs or inputs a different amount of total program memory different pro gramming languages different or additional programming or communication ports additional components less compo nents components with different configurations and a differ ent configuration as a whole The computer in the MCB may comprise an operator panel such as the G306 available from Red Lion Controls World wide Headquarters 20 Willow Springs Circle York Pa 17406 USA For example the Red Lion G306 is powered at 24 volts direct current VDC and comprises a color LCD monitor a touchscreen a software configuration a keypad for use with on screen menus LED indicators serial ports an ethernet port a facility for remote web access and control a USB port for downloading software configurations non volatile memory for storing software configurations a Com pactFlash mass storage device socket and a front panel sat isfying a National Electrical Manufacturers Association NEMA rating of 4x and an IP Code of IP66 However a computer may comprise other components and configura tions as well For
44. one embodiment when an apparatus or system accord ing to the invention is placed at a drilling site probes are placed in a mud tank and data is immediately calculated by micro processors and transmitted to a smart phone portable device computers on site or to remote corporate offices For example while in situ the apparatus or system may wire lessly transmit real time data regarding the mud in a down hole feed mud tank to a driller floor monitor a company man on a drill site and a corporate office monitoring a well Furthermore the apparatus or system may permit a driller to make real time decisions about mud conditions One embodiment of the invention provides graphs that show pressure at any point in the drilling process These graphs may be provided for example as electronic graphs that a user may download Another embodiment of the invention includes alarms that can be set to notify a driller when mudis too heavy or too light for the condition down hole For example the alarm may be 20 25 30 35 40 45 50 55 60 65 18 set by the driller with high and low limits In one embodiment these alarms can be used to reduce the liability associated with drilling a well In one embodiment the invention comprises an apparatus or system that is autonomous For example after connecting the apparatus or system to a power supply and setting up the apparatus or system in situ no additional actions are reguired
45. or housing 410a pipe 434 a 90 degree elbow 432 pipe 434 a 90 degree elbow 432 pipe 434 and the second cross fitting 427b on the second sensor housing 410b The third configuration 436 of PVC piping and fittings that secures the sensor housings 410a 410b in a substantially parallel orientation comprises from front to back in FIG 4B the first T fitting 422a on the first sensor housing 410a pipe 423 and the second T fitting 4225 on the second sensor housing 4108 Together the sensor housings 410a 410b and the three configurations 435a 435b 436 of PVC piping and fittings that secure the sensor housings 410a 4106 in a substantially parallel orientation may form a combined sensor housing As shown in FIG 4B the combined sensor housing is secured to the first flotation device 404a by wrapping a first two bands 426a around the first configuration 435a of PVC piping and fittings and the first flotation device 404a Likewise the sen sor housing is secured to the second flotation device 4045 by wrapping a second two bands 4266 around the second con figuration 4355 of PVC piping and fittings and the second flotation device 404b The sensor assembly 400 may be comprised of substan tially symmetrical components or substantially nonsym metrical components For example one or more floats and one or more sensor housings may be symmetrical or non symmetrical with respect to an axis or plane The sensor assembly may be comprised of substanti
46. picts a perspective view of one embodiment of a sensor assembly according to the invention FIG 4B depicts a perspective view of another embodiment of a sensor assembly according to the invention FIG 4C depicts a perspective view of one embodiment of a sensor housing according to the invention DETAILED DESCRIPTION OF THE INVENTION One embodiment of a method according to the invention will now be described with reference to FIG 2 First mud is pooled in a pooling step 202 Second in an insertion step 204 a sensor assembly comprising at least two corrosion resistant pressure sensors is inserted into the mud The pressure sen sors are each submerged at a different depth in the mud and separated by a known vertical distance given by subtracting the height of a first sensor in a vertical plane from the height of a second sensor in a vertical plane Third in a detection step 206 the pressures of the liquid at each of the sensors are measured to provide at least two pressures at liquid depths that are separated by the known vertical distance Thus the known vertical distance is equal to the difference in the liquid depths of the two sensors Fourth in a transmission of raw data step 208 raw data including the at least two pressure measurements provided by each of the sensors are transmitted to a Monitor Control Box MCB The MCB may comprise for example a compu tational device The term computational device includes but is
47. rence to FIG 1 First mud is pooled for example in a tank in a pooling step 102 Second a sample of the mud is collected in a known volume in a collection step 104 Third the mud is weighed in a weighing step 106 to obtain the mass of the mud Fourth the mud s density is calculated in a calculation step 108 using the known volume 25 40 45 50 60 2 and the mass of the mud Fifth the mud s density is reported to the drilling operator 110 This will permit the drilling operator to make adjustments to the mud s density if it is outside of a desirable density range and can provide useful information on down hole conditions There has been no reliable real time method of determin ing the density of drilling mud The old mud scale was the most reliable and simple way of making the determination but it does not provide real time data For example when drilling a well a mud sample typically will be drawn and density will be calculated once every hour for on shore wells and once every 15 minutes for off shore wells Thus if a mud density fluctuates soon after a sample is taken it may be 20 minutes before a drilling operator realizes that the density fluctuation has occurred This in turn may leave little time for implementing corrective measures to keep the mud density in a safe range or for taking other corrective measures to shut a well down Accordingly a device capable of measuring mud density in real time is desirabl
48. reover any combination of the above described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context ADDITIONAL EMBODIMENTS Various additional embodiments of the invention will now be described One embodiment is an apparatus for measuring in situ the density of a corrosive liquid such as drilling mud said appa ratus comprising at least two corrosion resistant pressure sensors separated by a known vertical distance on the appa ratus wherein the at least two pressure sensors comprise corrosion resistant fluid contacting parts In another embodi ment the corrosion resistant fluid contacting parts comprise a ceramic material In another embodiment the ceramic material is selected from the group consisting of dry ceramic capacitive CERTEC and high purity sapphire Ceramic In another embodiment the apparatus in situ is capable of transmitting real time continuous pressure measurements from the sensors which pressure measurements are convert ible to a density measurement of the corrosive liquid In another embodiment the at least two pressure sensors are fixed to at least one rigid body said rigid body comprising a float and at least one sensor housing In another embodi ment the at least two pressure sensors are housed in at least r 0 r 5 30 35 40 45 50 20 one sensor housing In another embodi
49. sensor element made from dry ceramic capacitive CERTEC and a base element and dia phragm made from high purity sapphire Ceramic Because the sensor element is a fluid contacting element it is subject to contact with the liquid For example a diaphragm in a sensor element that comprises a pressure transducer may be in direct contact with the liquid and thus be a fluid contacting part If the liquid is corrosive or fouling the sensor element can corrode or foul causing the sensor to fail For example if a sensor element comprises a pressure transducer a dia US 8 794 061 B1 19 phragm in the pressure transducer may experience unaccept able levels of corrosion if it is not made from corrosion resistant material In another embodiment the invention provides a method comprising the steps of pooling a corrosive liquid inserting into the liquid an apparatus comprising at least two pressure sensors separated by a known vertical distance so that the at least two pressure sensors are submerged in the liquid using the at least two pressure sensors to detect at least two pres sures of the liquid corresponding to at least two different liquid depths transmitting data comprising the at least two different pressures to a device capable of converting the pres sure data to a density using the device to convert the at least two different pressures into a density for the corrosive liquid and transmitting to a user a result comprising at leas
50. sor housing 410 as measured by the sensors 408a 408b are substantially similar to the properties of the liquid outside the sensor housing 410 In the sensor assembly 400 depicted in FIG 4A the first sensor 408a is in electronic communication with a power supply 314 through a line of electronic communication 406a between the first sensor 408a and the power supply 314 The first sensor 408a is in electronic communication with a moni tor control box 306 through a line of electronic communica tion 412a between the first sensor 408a and the monitor control box 306 Similarly the second sensor 4086 is in r 0 r 5 40 45 50 65 10 electronic communication with the power supply 314 through a line of electronic communication 406b between the second sensor 408b and the power supply 314 The second sensor 408b is also in electronic communication with the MCB 306 through a line of electronic communication 412b between the second sensor 4085 and the MCB 306 The sensors 408a 408b are supplied with power through their respective lines of electronic communication 4064 406b with the power supply 314 Furthermore the first pressure measured by the first sensor 408a and the second pressure measured by the second sensor 4085 may be transmitted to the MCB 306 through the sensors respective lines of electronic communication 412a 4126 with the MCB 306 One embodiment of a sensor assembly according to the invention will now be descr
51. stant caustic resistant base resis tant and acid resistant material in the context of drilling fluid other materials may also exhibit fouling resistance corro sion resistance abrasion resistance erosion resistance caustic resistance high pH resistance low pH resistance or some combination of these or other potentially desirable characteristics when exposed to a liquid including but not limited to muds cements slurries and solutions with fouling corroding abrasive erosive or other characteristics that tend to damage a pressure sensor or impede measuring the liquid s 20 25 30 35 40 45 50 55 60 65 16 pressure For example one characteristic of a diaphragm that makes it desirable is being sufficiently flexible to provide a measurable change in flex when the diaphragm is in contact with a fluid at different pressures An example ofa diaphragm characteristic that makes it resistant to exposure to harsh conditions in a fluid is being durable at least to a desired degree For example diaphragms made from metals are flex ible but will also dent if hit by a solid in a liquid for example a well cutting or a rock In contrast a ceramic diaphragm tends not to dent like a metal but breaks instead For example the ceramic diaphragm in the VEGAWELL 52 pressure trans mitter is resistant to a harsh environment durable measur ably flexible and hard but tends to break rather than dent One advantage of
52. sult the embodiment can run off of back up battery power for 36 hours in addition to running for 24 hours without a solar charge This is desirable for both environmental benefits and cost savings Another embodiment of the invention is highly portable comprising a light weight compact unit This unit may be flown to remote locations by light aircraft or shipped at low costs due to its compact size and light weight Furthermore because the unit can be constructed from weather proof com ponents and the mud probes can be made from highly durable 20 25 30 35 40 45 50 55 60 65 4 industrial materials the unit is capable of standing up to the rigorous conditions encountered at many drilling sites BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed characteristic of the invention are set forth in the appended claims The invention itself however as well as a preferred mode of use further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodi ments when read in conjunction with the accompanying drawings wherein FIG 1 is a flow chart representation of a prior art process for obtaining the density of a drilling mud FIG 2 is a flow chart representation depicting the overall process of one embodiment of the invention FIG 3 is a schematic depicting a system that is one embodiment of the present invention FIG 4A de
53. t each component may have its own power supply In other embodiments necessary power may be supplied to the components of the invention by using a variety of different component configurations For example various eguipment parts lines of electronic com munication and one or more power supplies may be com bined and arranged in a variety of ways The inventor anticipates that the eguipment and any con stituent components discussed in FIG 3 as well as any aux iliary equipment or components will be used in various con figurations For example all the eguipment may be located in substantially the same location The eguipment may be housed in a housing or not housed Housed equipment may be housed in a single housing or various components may be grouped together in separate housings For example in one embodiment an MCB 306 is located a distance from the sensor assembly 310 In another embodiment the MCB 306 is located at the sensor assembly 310 In one embodiment the PLC may be located at the sensor assembly 310 while the rest of the MBC 306 is located a distance from the sensor assem bly 310 As another example a user interface 302 may be located a distance from the MCB 306 Alternatively the user interface 302 may be located at the MCB 306 In one embodi 20 25 30 35 40 45 50 55 60 65 8 ment the power supply 314 may supply all the equipment shown in FIG 3 alternatively each piece of equipment or
54. t ID 35402 MezurX Products and Services Mud SentriX printed Feb 27 2014 located at http www mezurX Com Mudsentrix php 4 pages MD3018 Mud Density Remote Seal Differential Pressure Transmit ter for Drilling Mud Density and Cement Density Measurements Industrial Pressure Products Specifications 2005 AMETEK Inc SM0103T 210057 MD3018 Series Mud Density Transmitter Installation User Manual AMETEK Revision C May 2000 pp 1 14 MD3018 Mud Density Transmitter Overview AMETEK cited by examiner U S Patent Aug 5 2014 Sheet 1 of 5 US 8 794 061 B1 102 Prior Art INSERT ASSEMBLY 204 TRANSMISSION OF 208 RAW DATA STEP DATA CONVERSION TRANSMISSION OF 212 RESULTS FIG 2 104 106 108 110 U S Patent 302 306 Aug 5 2014 Sheet 2 of 5 USER INTERFACE MONITOR CONTROL BOX SENSOR ASSEMBLY POWER 314 SUPPLY FIG 3 US 8 794 061 B1 U S Patent Aug 5 2014 Sheet 3 of 5 US 8 794 061 B1 MONITOR CONTROL k 306 BOX POWER SUPPLY 400 4 U S Patent Aug 5 2014 Sheet 4 of 5 US 8 794 061 B1 420b 451b 7N 433b 405b Uy DYT jp 421b 422b 424 A 424 M 3 k ieee se Pa 434 a 4 X g 432 A U S Patent Aug 5 2014 Sheet 5 of 5 US 8 794 061 B1 US 8 794 061 B1 1 APPARATUS SYSTEM AND METHOD FOR MEASURING THE PROPERTIES OF A CORROSIVE LIQUID CROSS REFERENCE TO RELATED APPLICATION This application is a co
55. t the density for the corrosive liquid In another embodiment the invention comprises a system or apparatus that enables real time continuous analysis of process variables critical to drilling mud performance while the system or apparatus is in situ with respect to a fluid being analyzed For example while the apparatus is in place detect ing recording and transmitting information regarding the fluid being analyzed the apparatus or system can provide real time continuous information regarding process vari ables for example drilling mud density that are critical to drilling mud performance In one embodiment the system or apparatus in situ is capable of transmitting real time con tinuous pressure measurements from the sensors which pres sure measurements are convertible to a density measurement of a corrosive liquid While this invention has been particularly shown and described with reference to preferred embodiments it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention The inventor expects skilled artisans to employ such variations as appropriate and the inventor intends the invention to be practiced otherwise than as specifically described herein Accordingly this inven tion includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law Mo
56. the first sheath 405a This snug fit for example may fix the first sheath 405a in place with respect to the first sensor housing 410a In one embodiment the first seal 420a may for example comprise a PVC waterproof wire nut Because the first sheath 405a may comprise or enclose a suspension cable that suspends the first sensor 408a the first sheath 405a may be used in conjunction with a second sheath 405b and the first and second sensors housings 410a 410b to space the first and second sensors 408a 408b at a substantially known distance or even a sub stantially known vertical distance From bottom to top the second sensor housing 4105 com prises a second bottom end cap 4314 a pipe 429 a second coupling 428 a pipe 429 a second cross fitting 427b a pipe 429 a second T fitting 4226 and a second top end cap 451b Although for example the second coupling 428 need not be present However if the second coupling 428 is present it may be threaded to aid in adjusting the separation between the two sensors 408a 408b The second top end cap may be used to hold the second sensor 4085 in place From bottom to top the second top end cap 4515 comprises a second PVC adapter 4216 with one non threaded end and one threaded end a second threaded PVC plug 433b with an opening for the second sheath 4054 and a second seal 4205 between the second threaded PVC plug 4336 and the second sheath 4055 The second seal 4205 may for example comprise foam
57. the second height h2 The sensor housings 410a 4105 are both constructed from PVC piping and fittings although in another embodiment the sensor housings may be constructed from other appropriate materials for example plastics or welded metals such as stainless steel The first sensor housing 410a is longer than the second sensor housing 4106 so that the first and second pres sure sensors 408a 408b may be supported at the first and second heights hl and h2 respectively From bottom to top the first sensor housing 410a comprises a first bottom end cap 431a a pipe 429 a first coupling 430 a pipe 429 a first cross fitting 427a a pipe 429 a first T fitting 422a and first top end cap 451a Although for example the first coupling 430 need not be present However if the first coupling 430 is present it may be threaded to aid in adjusting the separation between the two sensors 408a 408b The first top end cap 451a may be used to hold the first sensor 408a in place From bottom to top the first top end cap 451a comprises a first PVC adapter 421a with one non threaded end and one threaded end a first threaded PVC plug 433a with an opening for the first sheath 405a and a first seal 420a between the first threaded PVC plug 433a and the first sheath 405a The first seal 420a may for example comprise a ceramic material foam plastic rub ber cork glue or another material to create a snug fit between the first threaded PVC plug 433a and
58. tion devices 404a 404b and to increase the distance separating the flotation devices to limit the tilt in the sensor housings caused by any disturbance in the surface of the liquid It may also be desirable to use a gyroscope to reduce tilt Alternatively it may be desirable to measure the angle of tilt of the sensor housings for example by using a gyroscope so that the known vertical distance D can be calculated from the mea sured angle of tilt and the vertical distance between the sen sors when the sensor housings are not tilted As another alternative it may be desirable to convert pressure readings from the sensors into information regarding the depth of the sensor in a liquid by using a recently calculated density of the liquid The information regarding the depth of the sensors could then be used to calculate an estimated angle of tilt by employing trigonometry In calculating an estimated angle of tilt it may be useful include one or more additional sensors at a fixed distance from one of the two sensors and not in line with the two sensors For example next to a first set of two sensors a second set of two sensors may be fixed a known distance from the first set of two sensors The pressure read ings may then be converted to liquid depths at each sensor using recently estimated densities The liquid depths at each sensor may then be used to obtain an angle of tilt Other approaches for obtaining an exact or approximate angle of tilt co
59. uld also be employed It is desirable that the at least one opening in each of the sensor housings 410a 4105 permits sufficient fluid commu US 8 794 061 B1 11 nication between the sensors 408a 408b and the liquid so that the properties of the liquid in contact with the sensors inside the sensor housings 410a 410b is substantially similar to the properties of the liquid outside the sensor housings 410a 410b even if for example the composition and the properties of the liquid are constantly changing In the sensor assembly 400 depicted in FIG 4B the first sensor 408a is in electronic communication with a power supply through a line of electronic communication between the first sensor 408a and the power supply The first sensor 408a is in electronic communication with an MCB through a line of electronic communication between the first sensor 408a and the monitor control box Similarly the second sen sor 408b is in electronic communication with the power sup ply through a line of electronic communication between the second sensor 4084 and the power supply The second sensor 408b is also in electronic communication with the MCB through a line of electronic communication between the sec ond sensor 4084 and the MCB The sensors 408a 408b are supplied with power through their respective lines of elec tronic communication with the power supply Furthermore the first pressure measured by the first sensor 408a and the second pressure m

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