阅读说明：本技术 使用三轴压力离心机设备测试石油物理性质 (Testing petrophysical properties using a three-axis pressure centrifuge apparatus ) 是由 穆斯塔法·哈基穆丁 于 2020-04-23 设计创作，主要内容包括：一种用于测试样品的性质的系统,所述系统包括测试单元。该测试单元包括单元外壳,该单元外壳具有第一端件、第二端件、以及在第一端件与第二端件之间延伸的至少一个壁。单元外壳限定包围单元的内部区域的压力边界。测试单元还包括设置在压力边界内的样品腔室、第一贮存器和第二贮存器。样品腔室限定内部区域。第一贮存器以流体连通的方式连接到样品腔室的内部区域。第二贮存器以流体连通的方式连接到样品腔室的内部区域。测试腔室还具有活塞组件,该活塞组件具有活塞流体腔室和活塞,该活塞具有延伸到活塞流体腔室中的杆。活塞部分地限定样品腔室。(A system for testing a property of a sample, the system comprising a test unit. The test unit includes a unit housing having a first end piece, a second end piece, and at least one wall extending between the first end piece and the second end piece. The cell housing defines a pressure boundary that surrounds an interior region of the cell. The test cell also includes a sample chamber disposed within the pressure boundary, a first reservoir, and a second reservoir. The sample chamber defines an interior region. A first reservoir is connected in fluid communication to an interior region of the sample chamber. A second reservoir is connected in fluid communication to the interior region of the sample chamber. The test chamber also has a piston assembly having a piston fluid chamber and a piston having a rod extending into the piston fluid chamber. The piston partially defines a sample chamber.)

1. A system for testing properties of a sample, the system comprising:

a test unit, the test unit comprising:

a unit housing including a first end piece, a second end piece, and at least one wall extending between the first end piece and the second end piece, the unit housing defining a pressure boundary enclosing an interior region of the test unit;

a sample chamber disposed within the pressure boundary, the sample chamber defining an interior region;

a first reservoir disposed within the pressure boundary, the first reservoir being connected in fluid communication to the interior region of the sample chamber;

a second reservoir disposed within the pressure boundary, the second reservoir being connected in fluid communication to the interior region of the sample chamber; and

a piston assembly including a piston fluid chamber and a piston having a rod extending into the piston fluid chamber, the piston partially defining the sample chamber.

2. The system of claim 1, further comprising a sheath surrounding the sample chamber, wherein the sheath is made of an electrically insulating material.

3. The system of claim 2, further comprising an electrical probe disposed between the sheath and the sample chamber or incorporated in the sample chamber.

4. The system of claim 1, wherein at least one wall of the first reservoir and at least one wall of the second reservoir have a neutral wettability.

5. The system of claim 1, wherein the first and second reservoirs are made of a material having low X-ray interference.

6. The system of claim 1, wherein the piston is made of a material with low X-ray interference.

7. The system of claim 1, wherein the pressure boundary is a first pressure boundary, wherein the first reservoir defines a second pressure boundary, and wherein the second reservoir defines a third pressure boundary.

8. The system of claim 1, further comprising at least one transducer operable to have a receive state and a transmit state.

9. The system of claim 8, wherein the at least one transducer is an acoustic sensor.

10. The system of claim 1, wherein the piston is movable in a first direction and a second direction within the interior region defined by the sample chamber.

11. A system for testing properties of a sample, the system comprising:

a test unit, the test unit comprising:

a cell housing defining a pressure boundary surrounding an interior region of the test cell;

a sample chamber disposed within the pressure boundary, the sample chamber defining an interior region;

a first reservoir disposed within the pressure boundary, the first reservoir being connected in fluid communication to the interior region of the sample chamber; and

a piston assembly including a piston fluid chamber and a piston having a rod extending into the piston fluid chamber, the piston partially defining the sample chamber.

12. The system of claim 11, further comprising a second reservoir disposed within the pressure boundary, the second reservoir being connected in fluid communication to the interior region of the sample chamber.

13. The system of claim 11, wherein the unit housing comprises:

a first end piece;

a second end piece; and

at least one wall extending between the first end piece and the second end piece.

14. A method, comprising:

loading the sample into the cell housing;

installing the unit housing in a tri-axial centrifuge;

applying an axial stress to the cell housing and sample such that the cell housing and sample receive an axial pressure; and

applying a second pressure to the sample, wherein the second pressure is less than the axial pressure and greater than ambient pressure.

15. The method of claim 14, wherein applying a second pressure comprises:

applying an overload pressure to an outer surface of the sample using a fluid.

16. The method of claim 15, further comprising:

applying a pore pressure to the sample that is less than the overload pressure by flowing a fluid into the sample.

17. The method of claim 14, further comprising:

altering at least one of the axial pressure, the second pressure, a test temperature, or a fluid, wherein the fluid applies the second pressure to the sample.

18. The method of claim 14, further comprising:

measuring an acoustic property of the sample using at least one transducer.

19. The method of claim 14, further comprising:

an electrical probe is used to measure an electrical property of the sample.

20. The method of claim 14, further comprising:

imaging the sample and the cell housing using x-rays.

21. The method of claim 14, further comprising:

performing at least one of a flow test, a capillary pressure test, an electrical property test, or a sound speed test on the sample.

22. The method of claim 21, wherein the flow test is a multi-speed flow test.

23. The method of claim 21, wherein the flow test is a single-speed flow test.

24. The method of claim 21, wherein the capillary pressure test is a multi-speed capillary test.

25. The method of claim 21, wherein the capillary pressure test is a single speed capillary test.

Technical Field

The present invention relates to a system and method for testing petrophysical properties using a three-axis pressure centrifuge system.

Background

Triaxial tests may be used to measure mechanical properties of subterranean formations. For example, in a triaxial shear test, stress is applied to a sample from a subterranean formation, and the stress along one axis is different from the stress in the vertical direction. Applying different compressive stresses in the test equipment resulted in shear stresses in the sample, and the load was increased and deflection was monitored until the sample failed. Pore pressure of a fluid (e.g., water or oil) and other properties in a sample may be measured during testing.

Disclosure of Invention

The systems and methods described herein enable various tests to be performed on a single system to measure and sense petrophysics, fluid phase behavior, formation damage, and enhance oil recovery data needed to estimate reservoir volume and hydrocarbon production. The system may measure electrical properties to calibrate electrical logging, fluid saturation, and Archie parameters, apply capillary pressures above 1000 pounds per square inch (psi) to perform fluid wettability tests, measure sound velocities for dynamic mechanical properties, perform x-rays for saturation profiles, perform reservoir fluid compressibility, and determine changes in fluid properties (static, dynamic, physical, and compositional). The same system is capable of performing these measurements and tests while applying the three-axis conditions observed in the field.

Some systems for testing properties of a sample include: a test unit, the test unit comprising: a cell housing comprising a first end piece, a second end piece, and at least one wall extending between the first end piece and the second end piece, the cell housing defining a pressure boundary enclosing an interior region of the cell; a sample chamber disposed within the pressure boundary, the sample chamber defining an interior region; a first reservoir disposed within the pressure boundary, the first reservoir being connected in fluid communication to the interior region of the sample chamber; a second reservoir disposed within the pressure boundary, the second reservoir being connected in fluid communication to the interior region of the sample chamber; and a piston assembly including a piston fluid chamber and a piston having a rod extending into the piston fluid chamber, the piston partially defining a sample chamber.

Some systems for testing properties of a sample include: a test unit, the test unit comprising: a cell enclosure defining a pressure boundary surrounding an interior region of the cell; a sample chamber disposed within the pressure boundary, the sample chamber defining an interior region; a first reservoir disposed within the pressure boundary, the first reservoir being connected in fluid communication to the interior region of the sample chamber; and a piston assembly including a piston fluid chamber and a piston having a rod extending into the piston fluid chamber, the piston partially defining a sample chamber.

Embodiments of these systems may include one or more of the following features.

In some embodiments, the system further comprises a sheath surrounding the sample chamber, the sheath being made of an electrically insulating material. In some cases, the system further includes an electrical probe disposed between the sheath and the sample chamber or incorporated in the sample chamber.

In some embodiments, at least one wall of the first reservoir and at least one wall of the second reservoir have a neutral wettability.

In some embodiments, the first reservoir and the second reservoir are made of a material having low X-ray interference.

In some embodiments, the piston is made of a material with low X-ray interference.

In some embodiments, the pressure boundary is a first pressure boundary, the first reservoir defines a second pressure boundary, and the second reservoir defines a third pressure boundary.

In some embodiments, the system further comprises at least one transducer operable to have a receive state and a transmit state. In some cases, the at least one transducer is an acoustic sensor.

In some embodiments, the piston is movable in a first direction and a second direction within an interior region defined by the sample chamber.

In some embodiments, the system further comprises a second reservoir disposed within the pressure boundary, the second reservoir being connected in fluid communication to the interior region of the sample chamber.

In some embodiments, the unit housing includes a first end piece, a second end piece, and at least one wall extending between the first end piece and the second end piece.

Some methods include: loading the sample into the cell housing; installing the unit housing in a three-axis centrifuge; applying an axial stress to the cell housing and the sample such that the cell housing and the sample receive an axial pressure; and applying a second pressure to the sample, wherein the second pressure is less than the axial pressure and greater than the ambient pressure. Embodiments of these methods may include one or more of the following features.

In some embodiments, applying the second pressure comprises applying an overload pressure to the outer surface of the sample using a fluid. In some cases, the method further comprises applying a pore pressure to the sample that is less than the overload pressure by flowing a fluid into the sample.

In some embodiments, the method further comprises altering at least one of the axial pressure, the second pressure, the test temperature, or the fluid, wherein the fluid applies the second pressure to the sample.

In some embodiments, the method further comprises measuring an acoustic property of the sample using at least one transducer.

In some embodiments, the method further comprises measuring the electrical property of the sample using an electrical probe.

In some embodiments, the method further comprises imaging the sample and the cell housing using x-rays.

In some embodiments, the method further comprises performing at least one of a flow test, a capillary pressure test, an electrical property test, or a sound speed test on the sample. In some cases, the flow test is a multi-speed flow test. In some cases, the flow test is a single-speed flow test. In some cases, the capillary pressure test is a multi-speed capillary test. In some cases, the capillary pressure test is a single speed capillary test.

In addition, the system can use reservoir pore pressure to perform formation damage studies on reservoir rock under tri-axial reservoir conditions, and can apply controlled capillary pressure. The system may also include materials that are corrosive and/or reactive to formation rock and fluids.

Some of these systems and methods may be used to perform cement testing to assess the properties of cement used in a reservoir. The properties may be, for example, thickening time, free water, cementation, setting time, sound velocity, electrical properties and mechanical strength. These tests may be conducted at reservoir temperature, pressure, and pore pressure in the presence of reservoir fluids and reservoir rocks. The instrument can also measure the flow properties of cement at all stages of the cement life cycle under triaxial and pore pressure conditions.

Some of these systems and methods may be used to study formation, decomposition, and production of gas hydrates using reservoir materials (sand, rock, fluid) under tri-axial and pore pressure conditions, as well as to study flow properties of reservoir materials under capillary pressure conditions.

Some of these systems and methods may be used to evaluate petrophysical properties of unconventional reservoirs (tight gas sands, shales, source rocks, etc.) under conditions of triaxial and pore pressures encountered in the reservoir under capillary pressure stress conditions. In addition, the system may provide the ability to simulate the fracturing and proppant injection tests required for the production of unconventional tight reservoirs.

The details of one or more embodiments of the systems and methods are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the systems and methods will be apparent from the description and drawings, and from the claims.

Drawings

FIG. 1 is a schematic perspective view of a system for performing a three-axis test of a sample using a centrifuge.

Fig. 2 is a schematic cross-sectional view of a test cell.

Fig. 3 is a schematic bottom view of a portion of the centrifuge apparatus of fig. 1.

Fig. 4 is a schematic view of a lid of the centrifuge apparatus of fig. 1.

Fig. 5 is a flow chart of a method for performing core analysis testing.

Fig. 6 is a schematic cross-sectional view of a test cell.

FIG. 7 is a flow chart of a method for performing phase behavior testing.

Fig. 8 is a schematic cross-sectional view of a test cell.

FIG. 9 is a flow chart of a method for performing cement testing.

Like reference symbols in the various drawings indicate like elements.

Detailed Description

The present specification describes systems and methods that can reconstruct reservoir conditions on a geological sample. These systems and methods may be used to generate reservoir temperature, reservoir confining pressure, reservoir axial stress, and reservoir pore pressure at capillary pressures encountered during reservoir production. These systems and methods may also be used to collect flow properties, pressure properties, temperature properties, x-ray properties, acoustic properties, electrical properties, and dimensional properties of a sample. Various tests may be performed by these systems, including, for example, single-speed flow tests, multi-speed flow tests, single-speed capillary tests, multi-speed capillary tests, electrical property tests, sonic speed tests, cement bond tests, and gas leak tests. The systems and methods may also be used to analyze generated data during testing by using artificial intelligence techniques.

FIG. 1 illustrates a system 100 for testing petrophysical properties of a sample disposed within the system 100 and collecting geomechanical information of the sample. System 100 includes a centrifuge device 102 and a computer system 103. The centrifuge apparatus 102 includes a centrifuge 104 and an x-ray device 106. Centrifuge apparatus 102 has a rotor 108 and a basket 110. This configuration can provide high capillary pressure by rotating the sample at a given number of revolutions per minute (rpm). The barrel 110 of the centrifuge device 102 has a first barrel window 112 and a second barrel window 114. Cover 116 of centrifuge device 102 has two cover windows 118, 120 aligned with barrel windows 112, 114 for x-ray scanning and visual scanning.

Computer system 103 is in communication with components of centrifuge device 102. Computer system 103 may be used to control the operation of centrifuge device and receive, process, and store data generated by centrifuge device 102. In system 100, computer system 103 is used to implement a neural network 115, which neural network 115 evaluates and processes the test being performed using the centrifuge system. An example of an implementation of a Neural Network is described in detail in U.S. patent application No. 16/131,341 ("inducing graphical Properties of hydrocarbons responses Using a Neural Network") filed on 14/9/2018. In system 100, computer system 103 is separate from centrifuge device 102. In some systems, computer system 103 is incorporated into centrifuge device 102.

The system 100 has four recesses 122, each sized to receive a test unit. In system 100, recess 122 is located in rotor 108 of centrifuge apparatus 102. In some embodiments, the centrifuge apparatus may have more than four recesses or less than four recesses. The number of tri-axial units placed in centrifuge apparatus 102 is based on the particular test parameters. In some embodiments, centrifuge apparatus 102 is a Roto-salana centrifuge commercially available from Hettich and configured to provide greater than 20,000 rpm.

The visual scan is performed by a fluid camera system 124 that includes a visual camera light source 126 and a visual camera 128. The vision camera light source 126 may be a flash and the vision camera 128 may be a high speed camera to capture images as the test proceeds. The fluid camera system 124 is designed to operate in both transmissive and reflective modes. The vision camera light source 126 and vision camera 128 may be mounted on opposite sides (e.g., top and bottom) or the same side (e.g., top) of the test sample and capture images using a mirror mechanism in the bucket 110. In the case of limited access to the bucket 100, a mirror mechanism may be used. In system 100, vision camera light source 126 is mounted above lid 116 of centrifuge device 102, and vision camera 128 is mounted below bucket 110. The use of such a fluid camera system 124 allows for reading of fluid volumes as they are produced.

The x-ray device 106 includes an x-ray source 130 and an x-ray camera 132. x-ray device 106 images test cell 134 received by recess 122 in rotor 108. x-ray camera 132 is disposed on lid 116 of centrifuge device 102 above first lid window 118.

The collected data may include, for example, acoustics, temperature, electrical, x-ray, saturation, fluid volume, rate of fluid volume, and saturation changes. The final composite image of the test progress can be combined with the log and seismic data for monitoring and assessing the effectiveness of the field treatment. Temperature sensors may be used to monitor temperature and the x-ray device 106 may be utilized to monitor saturation changes. Electrical data may be generated for wells for which a log is not available or for which the log is not representative of seismic data, acoustic data, a combination of electrical and saturation data, and well test information.

Centrifugal capillary pressure testing may be performed using centrifuge apparatus 102 under tri-axial, constrained and unconstrained stress conditions. In some embodiments, capillary pressures in excess of 20,000 pounds per square inch (psi) may be applied to the oil/gas/water system. The range of capillary pressures to be tested will depend on the type of reservoir. For example, for unconsolidated sand reservoirs, the capillary pressure may be in the range of 0.1psi to 100 psi; for conventional reservoirs, the capillary pressure may be between 1psi and 134 psi; and for unconventional reservoirs such as shale and Tight Gas Sand (TGS), the capillary pressure may be from 100psi to 100,000 psi. It should be noted that in the case of capillary pressures in excess of 30,000psi, sample integrity can be an issue. In many such cases, the strain measures may be created by increasing the triaxial stress. The tests may be performed as air/water, air/oil, water/oil on a rock sample, and in limited cases, as all three phases (air/oil/water) on a rock sample. Some systems allow for fluid extraction from reservoir core samples at capillary pressures of 20,000psi and higher. In some embodiments, capillary pressures above 20,000psi are obtained by increasing the motor speed, by increasing the size of the barrel 110, by increasing the distance between the test sample and the center of the centrifuge device 102, and/or by changing the sample size and orientation. In some embodiments, the test sample is loaded in the centrifuge apparatus 102 in a vertical orientation. In other embodiments, the test sample is loaded in the centrifuge apparatus 102 in a horizontal orientation. Some test specimens have a diameter of about 0.5 inch to about 8 inches and a length of about 0.5 inch to about 12 inches.

Fig. 2 shows a test unit 134 having a housing 136 containing a sample holder 138. The housing 136 includes a first end piece (base 140), a second end piece (end cap 142), a body 144 extending between the base 140 and the end cap 142, at least one electrical sensor 146, and at least one acoustic sensor 148.

The sample holder 138 is configured to hold a test sample 150, such as a solid core from a reservoir. Sample holder 138 includes a piston assembly 152 and a sheath (e.g., an electrical measurement sheath 154) extending between piston assembly 152 and base 140 of housing 136. In general, the material used for the sample-adjacent portions of the piston assembly 152 and base 140 should be x-ray transparent and have minimal or no electrical conductance, and may be, for example, a polyamide-imide (available from Solvay Plastics)Or glass. Piston assembly 152 includes a piston member 156 and a piston fluid chamber 158. An axial pressure fluid supply line 166 supplies fluid to the piston fluid chamber 158. Fluid chamber baseThe portion 160 has an opening through which the stem 162 of the piston member 156 extends. An end face of the piston member 156 engages a first end of the specimen 150.

Base 140 has an end face that engages a second end of sample 150, opposite the first end of sample 150. The sample 150 is accommodated between an end face of the piston member 156 and an end face of the base 140. When fluid is added to the piston fluid chamber 158 through the axial pressure fluid supply line 166, the end face of the piston member 156 exerts an axial force on the first end of the sample 150, causing an axial stress in the sample 150. The end surfaces of the piston assembly 152 and the base 140 may be coated with a coating such as teflonWill provide electrical isolation of the sample 150.

In some embodiments, sample holder 138 includes an electrical measurement sheath 154. The electrical measurement sheath 154 is an impermeable, elastomeric, rubber, or polyurethane sheath, and may be made of, for example, viton (available from DuPont)And (4) preparing. The electrical measurement sheath 154 is a tubular member that surrounds the sample 150. Piston seal 161 forms a seal between the inner bore of the first end of electrical measurement sheath 154 and the outer surface of piston member 156. The base seal 163 forms a seal between the inner bore of the second end of the electrical measurement sheath 154 and the outer surface of the base 140.

The electrical measurement sheath 154 is equipped with a sheath sensor 164 to provide additional measurements of the electrical characteristics and saturation distribution data of the test sample. The electrical measurement sheath 154 is made by incorporating the sheath sensor 164 during the vulcanization process of the sheath making. The type of sheath sensors 164, the number of sensors and their location are based on the sample size and sample properties, such as the mineral composition and homogeneity of the sample. The number of sheath sensors 164 in the electrical measurement sheath 154 may be increased and distributed so that various electrical measurements are performed on the sample 150 and the collected electrical measurements may provide an electrical image. Data collected by the sheath sensor 164 may be transmitted to the processing unit 170 via the lead 168. This type of data acquisition is very valuable for heterogeneous samples with layered, unconnected pore structures, cracks, kerogen concentrations, and other sample anomalies. Data from the plurality of sheath sensors 164 may be used to measure electrical resistance across the sample 150 and generate images of rock lithology and geology.

In some embodiments, the system 100 includes an electrical measurement feed 180 associated with the base 140. The base 140 is designed with an electrically insulating material and the material is embedded with electrodes (electrical sensors 146) for performing 2 or 4 electrode conductivity and resistivity measurements. An electrical measurement feed 180 is connected to the electrodes of base 140 (electrical sensors 146) to pass signals to processing unit 170 for collecting data from the natural state samples regarding reservoir salinity information, which will allow for better reserve estimation. In certain embodiments, electrical measurement feed 180 may provide current and measure voltage using a small battery-operated device (not shown) that may be mounted on rotor 108 of centrifuge apparatus 102 (FIG. 1) and connected to test unit 134.

Various electrical measurements may be made during the test. For example, in some embodiments, the electrical analysis of the sample 150 includes measuring at least one of the resistance, conductivity, capacitance, or impedance of the test sample. In some embodiments, the electrical analysis of the sample 150 includes measuring at least one of conductance, resistance, or impedance as a function of the variable frequency of the input current. In some embodiments, the end cap 142 of the housing 136 is designed such that the end cap 142 is isolated from the rest of the housing 136 and functions as an electrode. The body 144 of the housing 136 may be used as a ground to measure the electrical characteristics of the sample 150 during testing. Electrical measurements may be made in various ways during testing. In one method, centrifuge apparatus 102 is stopped at each capillary pressure equalization step, test unit 134 is removed from centrifuge apparatus 102, and the electrical characteristics of the sample in test unit 134 are measured. Based on the test design, an additional balancing step may be required. In some embodiments, there may be 2 to 15 balancing steps, and measurements may be performed at each step. In another approach, the processing unit 170 includes a battery operated electrical measurement device having the capability to collect time domain data that can be downloaded at the end of the test. The advantage of the second method is that it provides continuous measurements without the need to stop centrifuge apparatus 102, and also provides for transferring data between stages of capillary pressure equalization. The system 100 comprises a further processing unit 170, the further processing unit 170 being operable to collect data during testing of the sample and store the data for later download. In some embodiments, the data is downloaded in real time. The electrical data collected on the sample 150 may be collected at the same time as other data is collected, or in sequential steps with other data. In some embodiments, electrical sensor 146 measures an electrical characteristic of a fluid contacting a surface of housing 136.

Test unit 134 is illustrated as having a plurality of processing units 170. In system 100, computer system 103 and associated neural network 115 communicate with two processing units 170 in test unit 134. Some test units have a single processing unit. The processing unit may be incorporated into test unit 134 or located external to test unit 134. For example, in some systems, the computer system 103 and associated neural network 115 provide the functionality of the processing unit 170 and communicate directly with the sensors and valves of the test unit.

As previously described, the housing 136 includes a base 140, an end cap 142, and a body 144 extending between the base 140 and the end cap 142. The body 144 is a generally cylindrical member having an inner bore 172. The base 140 and end cap 142 are bolted to the body 144 of the housing 136. The housing seal 174 restricts fluid flow between the inner surface of the bore 172 and the outer surface of the reduced diameter portion of the end cap 142.

When assembled, the base 140, end cap 142, and body 144 define a unit chamber 176. A confining pressure fluid supply line 178 delivers fluid to the cell chamber 176 to apply biaxial stress to the sample 150.

In some embodiments, housing 136 is made of titanium. Titanium allowed testing to proceedAn x-ray scan is performed. In other embodiments, housing 136 is made of polyamide-imideOr glass. In general, the material used for test element 134 should be transparent to x-rays and have minimal or no electrical conductance. In further embodiments, housing 136 and sample holder 138 include both an inner coating and an outer coating that are both resistant to acid and corrosion resistant chemicals, such as hydrochloric acid, acetic acid, or other acids that will be used to simulate well cleaning and stimulation tests, as well as acids that will be used for chemical Enhanced Oil Recovery (EOR). Test unit 134 is capable of performing centrifugal saturation and capillary pressure tests under unconstrained, constrained, hydrostatic, or tri-axial test conditions.

The acoustic sensors 148 may each be an acoustic sensor having a P-wave component and an S-wave component. The acoustic sensor 148 may be a dual mode transducer capable of transmitting and receiving information. In some embodiments, the acoustic sensor 148 is located on the end cap 142 or in the end cap 142. In some embodiments, the end cap 142 is isolated from the body 144 of the sample holder 138 such that electrical characteristics can be measured using the electrical sensor 146 in the end cap 142 and the body 144 of the sample holder 138 as a ground. In such an embodiment, the electrical sensors 146 of the end cap 142 may provide electrical information to the processing unit 170 through leads.

The acoustic sensor 148 in the base 140 provides two functions. The acoustic sensor 148 provides pass-through transmission between the specimen and the two fluid chambers to provide an overall quality assessment when in transmission mode. In the reflection mode, both the top and bottom acoustic sensors provide specific changes within each fluid container, thereby providing an indication of the separation of the various fluids within the fluid chamber. Pore pressure fluids are sensitive to the pressure thereon because solids or gases may be generated due to pressure changes and may result in various fluid layers within the fluid chamber. The acoustic sensor will help understand the fluid behavior in each chamber, which may not be clearly observable using x-ray scanning of the fluid chamber alone. This function is important in systems that apply pore pressure, but is not relevant to systems that do not apply pore pressure to the sample. When there is no pore pressure, there is no fluid characteristic variation as a function of fluid pressure, so no bottom acoustic sensor is required.

Various acoustic measurements may be made during the test, including sound speed data. In some embodiments, the acoustic sensors 148 may collect compressional, shear, and/or stoneley wave data. The collected acoustic data may be communicated to the processing unit 170 over wires and analyzed for both time and frequency domains. Since one transducer may contain crystals of longitudinal and shear waves, the same acoustic sensor may collect a variety of waveforms. In a preferred embodiment, the acoustic sensor 148 is a transducer having a longitudinal wave component and a shear wave component mounted on the end cap 142 of the housing 136. In some embodiments, the acoustic sensor 148 is a dual mode transducer and operates in a reflective mode to transmit and receive sound waves. In some embodiments, the system 100 is operable to measure the speed of sound of the sample 150 and the speeds of the various fluids in the base 140. Before the test begins and once the test ends, the same acoustic sensor may perform all desired measurements with proper calibration of the acoustic sensor 148, depending on the rock sample properties and fluids used during the test. The speed of sound of the fluid in the base 140 can be used to analyze the production and presence of solid particles such as particulates, asphaltenes, and the like. In general, special care should be taken to ensure that the acoustic sensor 148 and associated components do not interfere with the electrical measurements. The acoustic data collected on the sample 150 may be collected simultaneously with other data or in sequential steps with other data.

The base 140 of the housing 136 includes a first reservoir 182 defined in the base 140. The end cap 142 of the housing 136 includes a second reservoir 184 defined in the end cap 142. Depending on the type of test, the first reservoir 182 and the second reservoir 184 may hold a fluid, such as a fluid sample from the sample 150, or a fluid to be injected into the sample 150, such as a solvent, acid, or chemical for EOR. The walls of the first and second reservoirs 182, 184 have a neutral wettability. Neutral wettability helps separate air, water and hydrocarbon fluids quickly and in sharp contrast. In some tests, the first reservoir 182 contained the first fluid 183 and the second reservoir 184 held the second fluid 185. The fluids may have different densities. For example, the first fluid 183 may be denser than the second fluid 185 to counteract the effects of density changes of the two fluids and simulate gravity changes during loading of a test sample.

As previously described, the base 140 and the end cap 142 are made of a material that provides low x-ray interference. This design limits interference when the x-ray device 106 images the fluid within the first reservoir 182 and the second reservoir 184.

The sample line 186 provides fluid communication between the sample holder 138 and the first reservoir 182. Pore fluid circulation system 188 also connects first reservoir 182 and second reservoir 184 with sample holder 138. The pore fluid circulation system 188 includes an access line 190 and a plurality of circulation lines 192 connected and controlled by a plurality of valves 194. The configuration of the pore fluid circulation system 188 and the reservoirs allows for different pressures to be applied to the first reservoir 182, the second reservoir 184, and the unit chamber 176. In effect, the housing 136 is the first pressure boundary. The first reservoir 182 and the second reservoir 184 are a second pressure boundary and a third pressure boundary, respectively, that are located within the first pressure boundary. In the test cell 134, a first reservoir 182 is disposed adjacent the base 140 of the housing 136 and a second reservoir 184 is disposed adjacent the end cap 142 of the housing 136. Placing the reservoirs and sample 150 within the housing 136 allows the tri-axial pressure applied within the test cell 134 to be applied to the first reservoir 182, second reservoir 184, and sample 150. The second pressure boundary and the third pressure boundary allow for controlling the pore pressure independently of the overload pressure. The application of independent pore pressure, overburden pressure, and tri-axial pressure by centrifuge apparatus 102 allows the system to more accurately simulate reservoir conditions than a system lacking such functionality. The pressure within the first reservoir 182 and the second reservoir 184 may be independently controlled and maintained below the tri-axial pressure exerted by the fluid in the cell chamber 176.

Test unit 134 may be used to perform experimental studies, including: generation mechanisms between various pore sizes (macro/micro/nano); understanding the imbibition/drainage of the base product between macro-micro pores; two-phase and three-phase relative permeabilities; two-phase and three-phase capillary pressures; chemical flooding EOR; wettability modification studies and the effectiveness of wettability modifying materials; acidification flow testing and effectiveness as a function of capillary pressure and injection sweep efficiency; residual oil production and sweep efficiency of Water Alternating Gas (WAG) at capillary pressure versus flow; young's modulus, Poisson's ratio and mechanical property test of envelope of destruction; hydrate formation, dissociation and production (flow) mechanisms as a function of temperature and/or pressure and/or composition; coalbed methane studies from intact test samples failed to obtain residual gas within the same set-up; formation damage studies related to damage due to injection fluids, production fluids, filtrate, stress changes, and temperature changes; enhancing oil flooding with a miscible fluid, an immiscible displacement fluid, a fluid reactive with a reservoir rock, and any combination thereof; proppant strength, proppant injection, and embedment within the reservoir; the interaction of the proppant with the reservoir fluid and the effect of the reservoir fluid on the integrity of the proppant; proppant fracture pore retention and its variation as a function of stress and fluid composition; proppant flowback characteristics, fracture closure and associated effects on reservoir production; research on unconventional shale, dense gas sand and tar sand; fine migration due to production, stress variations, and fluid composition variations; condensate flow test as a function of composition and pressure drop; condensate wettability and wettability change studies; low resistivity production zones were tested to understand formation brine salinity and its effect as a function of pore fluid in macropores, microporosites, and nanopores.

Fig. 3 is a perspective view of the tub 110 having a tub window 112. In some embodiments, the barrel window body 112 is made of a transparent material, such as glass. As shown in FIG. 1, a bucket window 112 is disposed on the bucket 110 to align with the x-ray source 130.

Fig. 4 is a perspective view of the cover 116 having a first cover window 118 and a second cover window 120. The first cover window 118 is opposite the keg window 112 and is aligned with the x-ray device 106 shown in fig. 1. The second cover window 120 is arranged to align with the vision camera light source 126 shown in fig. 1. The third cover window is arranged to align with the vision camera 128 shown in fig. 1.

Fig. 5 is a flow chart of a method 200 for performing a core analysis test on a sample at an elevated pore fluid pressure. Core analysis tests include, for example, permeability, solvent clean, saturation, and capillary pressure tests. Method 200 may be performed using test unit 134 shown in FIG. 2 and centrifuge device 102 shown in FIG. 1. To use the system 100, a sample 150 is loaded into the test cell 134 (step 202). Loading begins with the sample 150 being placed in an electrical measurement sheath 154. The body 144 of the test unit is bolted into place on the base 140. The sample 150 and the electrical measurement sheath 154 are then secured to the end piece of the base 140. O-ring 163 provides a seal when sheath 154 with sample 150 is mounted on base 140, so that sheath 154 is pressed against base 140 and seal 161 when pressurized fluid is injected. This creates a seal that limits the pressurized fluid from entering sample 150 within sheath 154. The end cap 142 is mounted on top of the body 144 and bolted in place to form a unit chamber 176 with the sample 150 and the electrical measurement sheath 154 inside. The test unit 134 is then placed in a centrifuge apparatus.

An axial stress (also referred to as axial pressure) is applied to the sample using the piston assembly 152 (step 204). Axial stress is controlled by the pass valve 194₅The fluid pressure applied to the piston fluid chamber 158 is determined. For example, an axial stress of 200psi may be applied. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. The neural network 115 evaluates the sample 150 using the procedure described in U.S. patent application No. 16/131,341 and replaces the sample if necessary. For example, a neural network may receive electrical data and may verify that the electrical data is within an appropriate range (e.g., a saline-saturated sample of a particular pore structure will have a different signal than an oil-saturated sample). Similarly, the acoustic (sonic) sensor signal is based on the internal structure of the sample and the fluid within the sample, andand the neural network can verify that the acoustic data is within the appropriate range. The x-ray data will also provide an indication of any physical changes (e.g., cracks generated within the sample). The neural network will evaluate these data against the trained model and establish sample integrity.

If the sample 150 is acceptable, an overload stress (also referred to as an overload pressure) is applied to the sample 150 (step 206). Centrifuge system utilization pass through valve 194₂Fills test cell 134 and passes through valve 194 before applying an overload stress below the level of axial stress₃The air is discharged out of the unit chamber 176. For example, an overload stress of 150psi may be applied. The overload fluid in the cell chamber 176 is fluidly isolated and sealed from the sample 150 by the base 140, the piston assembly 152, the electrical measurement sheath 154, the piston seal 161, and the base seal 163. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. Neural network 115 evaluates sample 150 and replaces it if necessary.

Optionally, pore pressure may be applied to the sample 150 at a level less than the overload stress level (step 208). Can pass through valve 194₁And valve 194₄Pore pressure is applied to the sample 150. For example, a pore pressure of 50psi may be applied to the sample 150. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. Neural network 115 evaluates sample 150 and replaces it if necessary.

After establishing these initial conditions, the axial pressure, overload pressure and pore pressure are increased to test the pressure conditions while maintaining the pore pressure less than the overload pressure and the overload pressure less than the axial pressure (step 210). This pressure relationship is important if the overload pressure becomes higher than the axial piston pressure, which will cause the axial piston to retract into the piston chamber, creating a gap between the sample 150 and the piston 162. This will cause sheath 154 to fail and allow the overload oil to invade sample 150, so the axial pressure must be higher than the overload pressure. If the pore pressure increases above the overload stress, this will cause sheath 154 to expand and seals 161 and 163 to fail, causing pore fluid to leak into the cell assembly and mix with the overload fluid, causing the test to fail. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. Neural network 115 evaluates sample 150 and replaces it if necessary.

After the test pressure condition is reached, the temperature in the test cell 134 is raised to the test temperature while maintaining the pore pressure less than the overload pressure and the overload pressure less than the axial pressure (step 212). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. Neural network 115 evaluates sample 150 and replaces it if necessary.

After the test pressure and temperature conditions are established, one or more core analysis tests (e.g., flow test, capillary pressure test, electrical property test, and sound speed test) are performed (step 214). The pore pressure in the sample 150 may be controlled by the fluid pressure in the first reservoir 182 and the second reservoir 184. The dual reservoir approach allows for independent control of the pore pressure based at least in part on the pressure of the test fluid in the first and second reservoirs 182, 184. The dual reservoir approach also allows two different test fluids to be applied to the sample 150, and allows one test fluid to be applied from one reservoir while the fluid flushed from the sample 150 is collected in the other reservoir.

The location of the two reservoirs 182, 184 within the pressure boundary of the test cell maintains the two reservoirs 182, 184 under pressure, which enables the fluids 183, 185 to be two different fluids with gases dissolved at pressure and temperature. For example, one fluid may be formation water with dissolved gas and another fluid may be formation oil with dissolved gas. The dissolved gas remains soluble in the liquid phase only due to the elevated pressure. Both fluids may be liquids, both gases, or one liquid and one gas.

During and after the test is performed, the acoustic data, electrical data, and x-ray data collected from acoustic sensor 148, electrical sensor 146, and x-ray camera 132 are fed to neural network 115 (step 216). Neural network 115 evaluates sample 150 and replaces it if necessary.

If the sample is still intact, other tests may be performed, or the same test may be performed under different conditions. For example, pressure conditions may be changed, temperature may be changed, pore fluid may be changed, or a combination of these changes may be applied (step 218).

After the test is complete, centrifuge device 102 returns to a state where the user can remove sample 150 and add a new sample. Centrifuge device 102 reduces the temperature of the sample to ambient conditions while maintaining the pore pressure less than the overload pressure and the overload pressure less than the axial pressure (step 220). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 148, electrical sensors 146, and x-ray camera 132 are fed into neural network 115. The pore pressure, axial pressure, and overload pressure are reduced to atmospheric conditions while maintaining the pore pressure less than the overload pressure and the overload pressure less than the axial pressure until the pressures sequentially reach atmospheric conditions (step 222). Acoustic data, electrical data, and x-ray data acquired from acoustic sensor 148, electrical sensor 146, and x-ray camera 132 are fed to neural network 115 (step 224).

The method 200 is described as being implemented in conjunction with a computer system 103 implementing a neural network 115. Although data communication and sample condition evaluation are described as being performed after each step, this is optional. Some methods are implemented with less frequent data communication and sample condition evaluation. Furthermore, the method 200 may also be performed in conjunction with conventional control and data acquisition computer systems that do not include neural networks. Without a neural network, automated monitoring and assessment of sample conditions must be performed manually.

Fig. 6 shows a test cell 300 that may be used to test the phase behavior of a sample. With someTest units unlike test units, test unit 300 can be centrifuged, which enables separationSuspended in waterParticles (wax, asphaltenes, sediment, etc.) which cannot be achieved without centrifugation of the pressurised unitSuspended in waterAnd (4) separating the particles. The test unit 300 may also be used to quantify the particles produced in each test step (particles cannot be quantified without centrifugation because they remain suspended or adhere to the unit inside the body). After separating particles based on their density using a centrifuge, the particles may be quantified using acoustic and x-ray analysis. x-ray and acoustic analysis also help to provide the size of these particles. The test unit 300 may also be used to separate fluids based on density changes. In particular, the test unit 300 may also be used to separate gases from other fluids and establish clear fluid boundaries to quantify various fluids. The test unit 300 may measure changes in electrical properties that are helpful in understanding the properties of the fluid and particles.

Test unit 300 includes a housing 310 that includes a first end piece (base 312), a second end piece (endcap 314), a body 316 extending between base 312 and endcap 314, at least one electrical sensor 318, at least one acoustic sensor 320, and a piston assembly 322. Body 316 is a generally cylindrical member having an internal bore. Base 312 and end cap 314 are bolted to body 316 of housing 310. The housing 310 may be made of, for example, titanium, polyamide-imideGlass material. Although not shown in FIG. 6, test unit 300 includes a processing unit similar to that described with respect to test unit 134.

Unlike test unit 134, test unit 300 does not include a separate sample holder. Instead, testing unit 300 holds the sample in sample chamber 324, which is defined between base 312, body 316, and piston assembly 322. In general, the material used for the piston assembly 322 and the base 312 should be x-ray transparent and have minimal or no electrical conductance, and may be, for example (available from Solvay Plastics)) Polyamide-imidesOr glass. The base 312 is flat to avoid uneven collection of solid particles during testing. Test unit 300 is shown with a first sample 325, a second sample 327, and a third sample 329 in sample chamber 324. During a typical phase behavior test, first sample 325 may be a solid or a fluid, second sample 327 may be a fluid, and third sample 329 may be a solid or a fluid.

Piston assembly 322 includes a piston member 326 and a piston fluid chamber 328. An axial pressure fluid supply line 330 supplies fluid to the piston fluid chamber 328. Piston member 326 has a stem 332 and a head 334. The piston fluid chamber base has an opening through which the rod 332 of the piston member 326 extends. An end face of piston member 326 defines one end of sample chamber 324.

First sample 325, second sample 327, and third sample 329 are contained between an end face of piston member 326 and an end face of base 312. When fluid is added to piston fluid chamber 328 through axial pressure fluid supply line 336, the end face of piston member 156 applies an axial force to first sample 325, thereby inducing an axial stress in the sample. The end surfaces of piston member 326 and base 312 may be coated with a coating such as teflonWill provide electrical isolation of the sample. A seal 335 is disposed between the piston head 334 and the wall 319 to limit or prevent fluid flow between the piston head 334 and the body 316.

Stem 332 of piston member 326 defines an internal passage 338 that extends to sample chamber 324. Internal passage 338 is attached to a conduit 339 that extends from rod 332 through piston fluid chamber 328 and end cap 314. Conduit 339 is made of a flexible material to compensate for movement of piston member 326 during testing. The test fluid may be supplied to the sample chamber 324 or the fluid may be withdrawn from the sample chamber 324 through the internal channel 338 and conduit 339.

The test unit 300 also includes two electrical probes 340 in the base 312 of the housing 310, and two acoustic sensors 342 (one in the base 312 and one in the endcap 314). The electrical probe 340 and the acoustic sensor 342 may be substantially similar to the electrical probe and the acoustic sensor described with respect to the test unit 134. Electrical probe 340 measures electrical properties of first sample 325, second sample 327, and third sample 329, and acoustic sensor 342 measures acoustic properties of first sample 325, second sample 327, and third sample 329. X-ray device 106 in centrifuge apparatus 102 images first sample 325, second sample 327, and third sample 329.

A test fluid conduit 344 extends through the base 312. Test fluid may be supplied to sample chamber 324 or fluid may be withdrawn from sample chamber 324 through test fluid line 344.

Three seals 346 are disposed between end cap 314 and body 316 to restrict or prevent fluid flow between end cap 314 and body 316. These three seals provide additional safety in handling fluids with high gas content and corrosive elements that may damage the O-rings (seals). If one of the seals (O-rings) is damaged, it will be indicated in both pressure changes and x-ray visualization. The test process can be safely stopped while the other seals are holding.

The test unit 300 may be used to perform experimental studies including: the method comprises the following steps of (1) testing the saturation pressure and strain point of bubbles, rapidly separating various fluids by using centrifugal force, and identifying phase boundaries and volumes of various fluids by using x-rays; the compressibility of the reservoir fluid as a function of temperature and composition; pressure-volume relationship of reservoir fluids as a function of temperature and composition; differential gas release test and compressibility of each stage left on the fluid; testing constant volume exhaustion; recombination of fluids for EOR studies of miscible and immiscible fluids; fluid-fluid compatibility of the injected fluid and the produced fluid with the reservoir fluid; predicting the wax appearance temperature and quantifying the quantity of the wax; asphaltene prediction and quantification and classification of asphaltenes, both in the suspended and precipitated phases; determination of asphaltene partial aggregation pressure, asphaltene coalescence pressure, and asphaltene deposition pressure; the influence of asphalt on the measurement of the sound velocity and the electrical property by utilizing the salt water saturated core plate is known; knowing the change in wettability as a function of pressure drop due to changes in the composition of the reservoir hydrocarbon fluids; studying the crystallization of salts as a function of temperature and pressure; studying hydrate formation and dissociation as a function of temperature, pressure, gas composition and brine salinity; knowing the start, size, quantity and type of hydrate; study emulsion formation, quantity and size as a function of temperature, pressure and composition; and condensate anti-enrichment treatment studies.

FIG. 7 is a flow diagram of a method 400 for performing a phase behavior test. Method 400 may be performed using centrifuge device 102 shown in FIG. 1 and test unit 300 shown in FIG. 6. First sample 325, second sample 327, and third sample 329 are loaded into test cell 300 (step 402). The body 316 of the test unit 300 is bolted in place on the base 312. Third sample 329 is placed in body 316, followed by second sample 327, and then first sample 325. End cap 314 with piston assembly 322 is placed over body 316 and bolted in place.

In some cases, the test is performed on a sample consisting of a single fluid (e.g., a gas saturated fluid). In this method, the piston 226 is brought into contact with the base 312 and the complete unit 300 is assembled. After the unit 300 is assembled, the chamber 328 is filled through line 336 and the chamber 328 is pressurized to the pressure of the test fluid. First, an inert fluid (typically a gas) is injected into the test cell 300 through line 336 to slightly separate the piston from the base 312 (-1 mm). Pressurized test fluid is then injected into test cell 300 through line 344 to load the desired amount of test fluid while moving piston 326 and maintaining pressure at all times. Once the test fluid is loaded, the inert fluid is removed from the test cell 300 via line 336. In some cases, sample 329 is a solid sample. Solid sample 329 is first placed in test cell 300 and piston 326 is brought into contact with solid sample 329. Then, the other test fluid is loaded as explained with reference to testing a single fluid sample. After the test unit 300 is placed in one of the recesses 122 of the centrifuge device 102, fluid is supplied to the piston fluid chamber 328 to move the piston head 334 into contact with the first test sample 325.

The pressure and temperature of the test cell 300 are raised to test conditions (step 404). The pressure may be increased by injecting an inert fluid (e.g., nitrogen) into sample chamber 324 through internal passage 338 and tubing 339, test fluid line 344, or both, while increasing the pressure in piston fluid chamber 328.

The test fluid is then introduced into the test cell 300 (step 406). The test fluid may be introduced into the sample chamber 324 through the internal channel 338 and conduit 339, the test fluid conduit 344, or both. Examples of test fluids include formation brine, oil, gas; a condensate; chemicals for enhanced oil recovery; fluids mixed with proppant for fracturing or other fluids produced or injected into the reservoir. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. Neural network 115 evaluates first sample 325, second sample 327, and third sample 329 and replaces these samples if necessary. For example, acoustic sensors, electrical sensors, and x-ray sensors provide information to the neural network about the fluid phase in the test chamber. The sample may be replaced if the received information does not match the predetermined range within which the neural network has been trained. For example, information from an acoustic sensor may be used to calculate the density of the sample(s); the resistivity/conductivity can be monitored using information from the electrical sensor; and phase separation or solid particles indicative of failure of the test fluid sample may be detected based on information from the x-ray sensor.

If the sample is acceptable, the test fluid is equilibrated for a desired time or parameter (step 408). After balancing, the acoustic, electrical, and x-ray data acquired from acoustic sensor 342, electrical sensor 340, and x-ray camera 132 are fed to neural network 115. Neural network 115 evaluates first sample 325, second sample 327, and third sample 329 and replaces these samples if necessary.

If the sample is still acceptable after equilibration, the system 100 performs a single speed test, a multi-speed test, or both (step 410). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. If additional tests are to be performed, at least the test parameters are changed (step 412). The test parameters may be changed by, for example, changing the test pressure, changing the test temperature, taking a fluid sample and performing a compositional analysis, and altering/changing the test fluid. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. Neural network 115 evaluates first sample 325, second sample 327, and third sample 329 and replaces these samples if necessary.

After the test is complete, the system 100 transitions to a mode in which the test sample may be removed and a new sample may be added. The system temperature is reduced to ambient temperature while keeping the pressure constant (step 414). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. The pressure is then reduced to ambient pressure (step 416). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115.

The method 700 is described as being implemented in conjunction with a computer system 103 implementing a neural network 115. Although data communication and sample condition evaluation are described as being performed after each step, this is optional. Some methods are implemented with less frequent data communication and sample condition evaluation. Furthermore, the method 200 may also be performed in conjunction with conventional control and data acquisition computer systems that do not include neural networks. Without a neural network, automated monitoring and assessment of sample conditions must be performed manually.

Fig. 8 shows a test unit 600 for testing cement set, set and integrity using centrifuge apparatus 102. The test cell 600 is constructed in a similar manner as the test cell 300, but is used to test the properties of a sample that may change from a fluid form to a solid form during a test cycle.

The test cell 600 includes a housing 610, the housing 610 including a first end (base 612) and a second end (end cap 614). A body 616 extends from the base 612 to the end cap 614. In the housing 610, the base 612, the end cap 614, and the body 616 are three distinct components that are bolted together.

The test unit 600 also includes a piston assembly 618 having a piston 620 and a piston fluid chamber 622. The body 616, base 612, and end cap 614 define a piston chamber 624. An axial hydraulic fluid line 625 extends through the end cover 614 and may be used to supply and remove hydraulic fluid to and from the piston fluid chamber.

A rubber boot 626 extends within the piston chamber 624 parallel to the body 616. The piston 620 has a head 628 and a stem 629 and is movable within the piston chamber 624. The head 628 of the piston 620 is sized to move within the rubber sheath 626. An O-ring between the rubber jacket 626 and the head 628 creates a fluid seal to limit or prevent movement of the test sample through the head 628. The base 612, head 628, rubber jacket 626 of the housing 610 define a sample chamber 630 within the piston chamber 624.

The test cell 600 includes a first carrier fluid line 632 defined to extend through the base 612 to the piston chamber 624, and a second carrier fluid line 634 defined to extend through the end cap 614 to the piston chamber 624. The stem 629 of the piston member 326 defines an internal passage 636 that extends to the sample chamber 630. The internal passage 636 is attached to a conduit 638 extending from the rod 629, through the piston fluid chamber 622 and the end cap 614. The conduit 638 is made of a flexible material to compensate for movement of the piston 620 during testing. The test fluid may be supplied to the sample chamber 630 or the fluid may be withdrawn from the sample chamber 630 through the internal channel 636 and the conduit 638. A test fluid line 640 extends through the base 612. The test fluid may be supplied to the sample chamber 630 or the fluid may be withdrawn from the sample chamber 630 through the test fluid line 640.

In use, the head 628 contacts the water layer 602 and exerts a pressure (up to 50,000 psi) on the water layer 602. The water layer 602 and the cement slurry 604 undergo a phase change from fluid to solid while in the sample chamber 630. The pore pressure created by flowing the test fluid into sample chamber 630 may be applied to the sample before, during, or after the phase change. This method can simulate fluid flow during various stages of cement testing while determining permeability because there is formation fluid that may invade the cement during setting and curing. The method also simulates the effect of fluid flow on the quality of the final set cement, including the effect of reactions between cement components and fluid, to help evaluate and improve the cement and design a better cement. The piston 620 is capable of moving a distance of at least three times the length of the test specimen.

The rubber jacket 626 extends only partially up the body 616 from the base 612 toward the end cap 614. The rubber jacket 626 contacts the base 612 of the housing, but does not reach the end cap 614 of the housing 610. Instead, rubber boot 626 is shorter than body 616 to provide an opening 641, which opening 641 facilitates fluid communication between first space 642 in piston chamber 624 and an external passage 644, wherein said external passage 644 is defined between rubber boot 626 and body 616. Similar to sample chamber 630, first space 642 is defined in part by head 628 and rubber jacket 626. However, a first space 642 is defined by a side of the head 628 opposite the sample chamber 630. Thus, piston chamber 624 includes sample chamber 630, first space 642 and external passage 644. The head 628 and stem 524 extend into the piston chamber 624 to apply mechanical pressure and test fluid (pore) pressure to the cement slurry and associated water layer.

Movement of the head 628 changes the volume of the first space 642 and the sample chamber 630. For example, as the head 628 moves toward the water 602, the volume of the first space 642 increases, while the volume of the sample chamber 630 decreases. The volume of outer passageway 644 remains constant regardless of the position of piston 620 because, unlike first space 642 and sample chamber 630, outer passageway 644 is not defined by piston 620. The outer passage 644 facilitates the flow of pressurized fluid that fills the first space 642.

The test unit 300 may be used to perform experimental studies including: cement thickening time test under true triaxial conditions with pore pressure with or without reservoir rocks and casing; a record of cement setting and setting time and dynamic changes before, during and after setting/setting; measurement of free water before and after cement setting to assess cement hydration and sealing ability; fluid injection for assessing the permeability of the cement matrix; fluid flow for measuring the seal strength and effectiveness between cement and reservoir rock and casing material; measurement of solid/liquid/gas additive dispersion during setting and curing of cement; hydrostatic strength testing of set cement and leakage/sealing capability during various stages before and after failure; triaxial compression strength testing of set cement and leakage/sealing capability during various stages before and after failure; the poisson's ratio and young's modulus of cement for static and dynamic; the effect of drilling fluids on the ability of cement to bond with reservoir rocks and casings; the effect of acidizing and fracturing fluids on cement; gas migration study; and measurements for calibrating electrical properties and acoustic velocity of the bond record.

Fig. 9 is a flow chart of a method 700 for performing coagulation, cure, and integrity tests. Method 700 may be performed using test unit 600 shown in FIG. 8 and centrifuge device 102 shown in FIG. 1.

Test cell 600 is assembled by bolting body 616 to base 612 and end cap 614 to body 616 with rubber jacket 626 in place. If hollow reservoir rocks are included, the hollow reservoir rocks are loaded into the sample chamber 630 during the assembly process (step 702). Fluid is supplied to the piston fluid chamber 622 through an axial hydraulic fluid line 625 to extend the piston 620 and bring a head 628 of the piston 620 into contact with the base 612 or hollow reservoir rock (if present). The piston chamber 624 is filled with the overload fluid through the second carrier fluid line 634 while air is vented through the first carrier fluid line 632. After establishing these initial conditions, the pressure and temperature in the test cell 600 are raised to the test conditions (step 704).

Cement slurry being tested is injected into the sample chamber 630 through the test fluid line 640 (step 706). When cement slurry is being injected, hydraulic fluid is released from the piston fluid chamber 622 through the axial hydraulic fluid line 625, and overload fluid is released from the piston chamber 624 through the first carrier fluid line 632. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. The neural network 115 evaluates the sample and replaces it if necessary. For example, acoustic data, x-ray data, and electrical sensor data are fed to a trained neural network to confirm that the cement components are not separated, and that particles, fluids, and gases are uniformly distributed. For example, in the case of cement having fibers, beads or gas (foam cement), it is important that the dispersion be uniform during loading of the cement slurry, curing and setting.

The system 100 then injects water into the sample chamber 630 until a desired volume of free water 602 is present on top of the slurry 604 (step 708). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. The neural network 115 evaluates the sample and replaces it if necessary.

The cement slurry 604 is set and cured (step 710). During this process, the cement slurry absorbs water from the free water layer 602. Based on the test pressure and test temperature, the cement can set and cure for hours to weeks. All pressures (axial, confining/overload and pore pressures are applied and maintained during loading, setting, curing of the slurry and during any testing during/after curing/setting acoustic, electrical and x-ray data collected from acoustic sensor 342, electrical sensor 340 and x-ray camera 132 are fed to neural network 115 during the setting and curing process after the setting and curing process is complete acoustic, electrical and x-ray data collected from acoustic sensor 342, electrical sensor 340 and x-ray camera 132 are fed to neural network 115 the sample is evaluated by neural network 115 and replaced if necessary.

The remaining free water 602 is removed from the set and cured cement 604 and measured (step 712). Before performing the test, acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed into neural network 115.

If the sample is still acceptable, the system 100 performs one or more tests associated with the cement test (step 714). Suitable tests include, for example, flow tests, capillary pressure tests, electrical property tests, sound speed tests, cement bond tests, gas leak tests, mechanical tests, and failure tests. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. If additional tests are to be performed, at least the test parameters are changed (step 716). The test parameters may be changed by, for example, changing the test pressure, changing the test temperature, and altering/changing the test fluid. Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. The neural network 115 evaluates the cement slurry 604 and replaces the sample if necessary.

After the test is complete, the system 100 transitions to a mode in which the test sample can be removed and a new sample can be added. The system temperature is reduced to ambient temperature while keeping the pressure constant (step 718). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115. The pressure is then reduced to ambient pressure (step 720). Acoustic data, electrical data, and x-ray data acquired from acoustic sensors 342, electrical sensors 340, and x-ray cameras 132 are fed to neural network 115.

The method 700 is described as being implemented in conjunction with a computer system 103 implementing a neural network 115. Although data communication and sample condition evaluation are described as being performed after each step, this is optional. Some methods are implemented with less frequent data communication and sample condition evaluation. Further, method 700 may also be performed in conjunction with a conventional control and data collection computer system that does not include a neural network. Without a neural network, automated monitoring and assessment of sample conditions must be performed manually.

Various embodiments of systems and methods have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.