CN111879680A - Compact rock permeability testing device and application method thereof - Google Patents
Compact rock permeability testing device and application method thereof Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 44
- 238000012360 testing method Methods 0.000 title claims abstract description 42
- 230000035699 permeability Effects 0.000 title claims abstract description 36
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000007789 gas Substances 0.000 claims abstract description 65
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- 238000002474 experimental method Methods 0.000 claims abstract description 26
- 230000035485 pulse pressure Effects 0.000 claims abstract description 23
- 238000002347 injection Methods 0.000 claims abstract description 10
- 239000007924 injection Substances 0.000 claims abstract description 10
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- 238000007789 sealing Methods 0.000 claims abstract description 4
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 51
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 49
- 229910052757 nitrogen Inorganic materials 0.000 claims description 23
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- 206010063385 Intellectualisation Diseases 0.000 claims description 3
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- 229910018487 Ni—Cr Inorganic materials 0.000 description 2
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
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- 239000000463 material Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
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- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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Abstract
The invention discloses a compact rock permeability testing device and an application method thereof, and is characterized by comprising the following steps: the device comprises a clamping device part, a pulse part, a gas injection part, a temperature control part, a vacuum part, a metering part and a data acquisition and processing system. The method comprises the following steps that an initial pressure is provided for a testing system by a gas injection part, a pulse pressure is provided for a holder part by a pulse part, the temperature of the measurement part and the temperature of the holder part are controlled by a temperature control part, the system is vacuumized by a vacuum part, and experimental data are processed by a data acquisition and processing system. The invention can simultaneously realize gas replacement and research the influence of different gases on permeability measurement, has good sealing performance and accurate pressure control, can reduce the influence of switch closure on experimental results, can simply, conveniently and accurately measure the volume of upstream and downstream pipelines, can measure the permeability of the rock core for multiple times in one experiment, has simple operation, high testing efficiency and wide application, and obtains accurate and visual results.
Description
Technical Field
The invention relates to the technical field of unconventional reservoir gas exploitation, in particular to a tight rock permeability testing device and an application method thereof.
Technical Field
In recent years, with the storage of conventional energy sources being less and less, the exploitation depth, difficulty and the like are greatly increased, and in contrast, shale gas exploitation belongs to a new industry, and the exploration amount of shale gas is increased year by year, so that shale gas is widely noticed by various countries and becomes one of the hot spots of research in the field of oil and gas. The technology of shale gas in China can acquire resources in an amount of more than 36 billions of cubic meters, and is in the front of the world. The reasonable development and utilization of the shale gas have important significance for reducing the dependence of China on conventional energy and improving the energy industrial structure of China. However, in the shale gas exploitation process, because the shale reservoir is thick, the porosity of the shale is small, the permeability is extremely low, and the accurate measurement of the permeability of the shale reservoir has certain difficulty.
Before the invention, the invention with the patent number of 201810097759.4 discloses an experimental device for triaxial permeability test, which can apply axial pressure and confining pressure in a triaxial loading manner, and calculate the permeability of a rock sample by measuring attenuation data of pressure pulses applied at an inlet end of the rock sample in the rock sample, but in the experimental process, pressurized gas cannot be directly stored, the volume of a pulse chamber cannot be changed, valves of a control system are all manual valves, the pressure is easily influenced by the closing of a switch, a pressure sensor is single, a proper range cannot be selected according to the specific experimental pressure, the pipeline volume cannot be calculated in the testing process, the initial pulse pressure is excessively estimated, and errors also exist in the calculation of the reservoir volume.
Aiming at the defects of the device, the compact rock permeability testing device and the application method thereof are needed, wherein the compact rock permeability testing device can store a plurality of gases, can select different reservoir body volumes and pressure sensors with different measuring ranges according to an experimental scheme, can directly calculate the pipeline volume in the experimental process, and has the advantages of high measurement precision, simple instrument operation and accurate and visual experimental results.
Disclosure of Invention
The invention adopts an inlet clamp holder with good tightness and an ISCO pump capable of accurately controlling axial pressure and annular pressure, the volume of a pulse chamber is variable by controlling the closing of a valve, the closing of a valve of a test system is controlled by adopting a pneumatic valve with good switching performance, fast switching speed, high pressure resistance, corrosion resistance and good sealing performance, the pressure reading precision is improved by adopting a multi-range pressure sensor, the pipeline volume is directly measured in the experimental process, the upstream reservoir volume and the downstream reservoir volume are corrected to obtain real pulse pressure, the requirements of different experimental schemes are met by a plurality of gas storage tanks, and the precision and the efficiency of a compact rock permeability testing device are improved.
The technical scheme is as follows:
the device for testing the permeability of the dense rock comprises a holder part, a pulse part, a gas injection part, a temperature control part, a metering part, a vacuum part and a data acquisition and processing system.
In the clamp holder part, the working pressure of the clamp holder can reach 137.9MPa, the working temperature can reach 148.9 ℃, the tightness is good, the real situation of a high-temperature and high-pressure stratum can be accurately simulated, and the axial pressure and the ring pressure are accurately controlled by adopting an ISCO pump with the measuring range of 0-70MPa in the experimental process.
The pulse part, the two cavities that the volume is 20ml and 70ml are respectively adopted to the upper and lower reaches, the error that internal volume changes can effectively be prevented to the cavity design because of operating pressure height, high temperature cause, can change the volume ratio of upper and lower stream cavity through adjusting the pneumatic valve, totally 9 different volume combination modes, can effectually be suitable for different experimental scheme, improve testing arrangement's usability, reduce because the experimental error that different cavity volumes and pore volume ratio brought.
The gas injection part boosts the test gas through the gas booster pump, stores the boosted gas in the storage tank, adjusts the driving gas pressure reducing valve to obtain the appointed pulse pressure, and can avoid the complexity of repeated pressurization and test gas replacement when carrying out the experiment of the storage tank gas after the pressurization or adopting different storage tank gases in the next laboratory.
The temperature control part is provided with a rotary split door with an observation window on the front side, a heat insulation window is arranged in the rotary split door, a high-precision temperature controller, a touch key type power supply, a heating (nickel-chromium wire heater), a fan (brand new high-temperature resistant long-shaft motor and turbofan) switch and the like are designed on the rotary split door, and the measuring range is normal temperature to 200 ℃.
The metering part comprises pressure sensors with different measuring ranges, a sensor with a similar measuring range can be selected according to the experimental pressure, the reading error is reduced, the static pressure of the differential pressure sensor is 4500psi, the measuring range is 0-2 MPa, and the precision is 0.05%; the stroke of the displacement sensor is 10mm, the precision is 0.1%, the motion mode is linear displacement, and the repeatability is 0.002 mm.
The vacuum part comprises a vacuum pump, a vacuum meter and a vacuum buffer container, and the vacuum degree is 6 multiplied by 10-2Pa, and the discharge capacity of a vacuum pump is 8L/s.
The data acquisition and processing system mainly comprises the formation of pressure signals, the formation of differential pressure signals and an interface with a microcomputer, the system mainly adopts a communication adapter card of Hongge company, the acquisition software is combined to realize the acquisition in time, the system matching software can be operated under a Windows platform, the interface is friendly, and in the data acquisition process, the whole-process graph monitors the changes of pressure, differential pressure and the like. The test precision of the whole system can be ensured, and the intellectualization of each system is realized.
The clamp holder part, the pulse part and the metering part are controlled by adopting pneumatic valves with good switching performance, fast switching speed, high pressure resistance, corrosion resistance and good sealing performance, the opening and the closing of the clamp holder part are controlled by air source pressure, and the precision of an experimental result can be effectively improved by direct control of a computer.
The specific application method for testing the permeability of the compact rock is as follows:
the core is placed in a core holder (50) and both axial and confining pressures are applied to 7 MPa. And the instrument was flushed with nitrogen. To eliminate the temperature error for the experiment, the whole apparatus was placed in an incubator (68) set at 25 ℃. + -. 0.5 ℃.
A first set of experiments was carried out with an upstream 20ml chamber (46) having a volume V1Setting the initial pressure to P0The valves (10), (11), (14), (18), (20), (24), (25), (27) are opened. Due to the experimental facilityThe applied pore pressure is less than 6MPa, and in order to improve the measurement accuracy, a pressure sensor with the 6MPa measuring range is adopted to open the valves (12), (17) and (21). After the system pressure is balanced, the valves (14), (20) are closed.
By adjusting the pressure reducing valve (42), the pressure delta p is increased upstream1Closing the valve (10) and recording the reading p of the lower pressure sensor I after the pressure is balanced1. Opening the valve (14) and recording the reading p when the reading of the pressure sensor II is not increased and is equal to the reading of the pressure sensor I2Recording the pressure p after the system has been balanced3(since the gas transport velocity in the pipeline is much higher than the core velocity, this process is extremely short and is completed in a few seconds, and we believe that the core face pressure has not changed before it is captured by the pressure sensor II, so the actual pulse pressure Δ p0Is p2And p0The difference of (d). The first formula for calculating the volume of the pipeline can be obtained according to Boyle's law and the gas equation of state
p1(V1+V3+V5)＝p2(V1+V3+V4+V5)
Closing the valve (24), opening the valve (26), recording the pressure p at that time after the pressure has stabilized4After a stabilization, the valve (24) is opened, after which the reading of the pressure sensor is suddenly increased and then slowly increased, and the critical pressure p is recorded5. (in tight rock, the differential pressure between the upstream and downstream reservoirs is small, the downstream pressure changes slowly, and when the valve (24) is opened, the pressure in the pipe and chamber quickly reaches equilibrium). Obtaining other two calculation formulas for calculating the volume of the pipeline
p3(V1+V5+V7)＝p4(V1+V2+2V5+V7)
p3V6+p4(V1+V2+2V5+V7)＝p5(V1+V2+2V5+V6+V7)
Closing the valve (27) and adjusting the upstream pressure to an initial stable pressureIs again p0While, the pressure Δ p is also added upstream1And after the pressure is stabilized, opening the valve (14) to finish the second pulse. Then the valves (26), (27) are opened for a third pulse.
A second set of experiments was performed using an upstream 70ml chamber, with a volume V2When the initial pressure p0Repeating the step (3) after stabilization, and recording the index p before the formal pulse6，p7(to ensure that the true pulse pressure is close to or the same, the initial pulse pressure Δ p is applied in view of the increase in the volume of the chamber2Slightly less than Δ p1). By adjusting the valves (26), (27), a second set of triple pulse data is recorded. Obtaining the 4 th calculation formula of the pipeline
p6(V2+V3+V5)＝p7(V2+V3+V4+V5)
The valves (11), (13) are opened and a third set of experiments is performed with the upstream 90ml chamber, when the initial pressure p is reached0Repeating the step (3) after stabilization, and recording the index p before the formal pulse8，p9At this time, the initial pulse pressure Δ p3Slightly less than Δ p2Third set of triple pulse data is recorded, again by adjusting valves (26), (27). Obtaining the 5 th calculation formula of the pipeline
p8(V1+V2+V3+2V5)＝p9(V1+V2+V3+V4+2V5)
Wherein, V3The volume of an upstream communication pipeline between the valve (10) and the valve (14) and the volume of a cavity in the pressure sensor I are shown; v4The volume of a communication pipeline from the valve (14) to the left end face of the rock core and the volume of a cavity in the pressure sensor II are represented; v5The volume between the outlet of the chamber (46) and the chamber valve (11) is shown, and since the chamber is manufactured in a customized way and is symmetrical up and down, the volumes between the outlet of the four chambers and the chamber valve are all equal to be V5；V6Is the volume of a communication pipeline between the right end face of the rock core and the valve (24), V7Is the communication pipe volume and pressure sensing downstream of the valve (24)Cavity volume within vessel iii. From these 5 equations 5 unknowns V can be calculated3，V4，V5，V6，V7。
The permeability of the rock sample was calculated using the formula:
in the formula, pu(t) is the upstream pressure at time t; p is a radical offThe pressure is the equilibrium pressure after the pulse is finished; Δ p is the true pulse pressure, p in each of the three experiments2-p0、p7-p0、p9-p0；VdThe corrected reservoir volume downstream is considered; vuTo account for the corrected volume upstream of the tube volume; alpha is pu(t)-pfThe slope on a semi-logarithmic graph with time t; k is the permeability of the rock sample; a is the cross-sectional area of the rock sample; mu is the viscosity coefficient of the experimental gas; beta is the isothermal compression coefficient of the experimental fluid; l is the length of the rock sample, f is a compressed storage factor and is related to the volume of the upstream and downstream reservoir bodies and the pore volume, and specifically, f is theta 2/(a + b), and a is Vp/Vu,b＝Vp/VdAnd theta is a solution of the transcendental equation tan theta ═ b (a + b) theta/(theta ^ 2-ab).
Drawings
The invention is further described with reference to the following figures and detailed description:
FIG. 1 is an experimental schematic diagram of the testing apparatus of the present invention.
In the figure: 1, other gas valves; 2, a nitrogen gas valve; 3, a methane valve; 4, driving a gas inlet valve; 5, a high-pressure nitrogen outlet valve; 6, a nitrogen pressure reducing valve; 7, a high-pressure methane outlet valve; 8, a methane outlet valve; 9, an emptying valve; 10, pneumatic valve v1(ii) a 11, air-operated valve v2(ii) a 12, pneumatic valve v3(ii) a 13, an air-operated valve v4(ii) a 14, pneumatic valve v5；15，Pneumatic valve v6(ii) a 16, pneumatic valve v7(ii) a 17, air-operated valve v8(ii) a 18, pneumatic valve v9(ii) a 19, differential pressure manual valve; 20, pneumatic valve v10(ii) a 21, air-operated valve v11(ii) a 22, pneumatic valve v12(ii) a 23, air-operated valve v13(ii) a 24, pneumatic valve v14(ii) a 25, pneumatic valve v15(ii) a 26, pneumatic valve v16(ii) a 27, air-operated valve v17(ii) a 28, pneumatic valve v18(ii) a 29 air-operated valve v19(ii) a 30, vacuum manual valve; 31, a nitrogen gas cylinder; 32, a methane cylinder; 33, muting an air compressor; 34, driving a gas pressure reducing valve; 35, driving a pressure gauge; 36, nitrogen, methane and other gas cylinder pressures; 37, a booster pump; 38, nitrogen storage tank pressure gauge; 39, nitrogen pressure reducing valve; 40, outlet pressure gauge of nitrogen pressure reducing valve; 41, methane storage tank pressure gauge; 42, methane pressure reducing valve; 43, outlet pressure gauge of nitrogen pressure reducing valve; 44, a nitrogen storage tank; 45, a methane storage tank; 46, upstream 50ml chamber; 47, upstream 100ml chamber; 48, an axial pressure pump; 49, a ring pressure pump; 50, a core holder; 51, a vacuum buffer container; 52, a vacuum gauge; 53, a vacuum pump; 54, a displacement sensor; 55, downstream 100ml chamber; 56, downstream 50ml chamber; 57, a first pressure sensor; 58, a second pressure sensor; 59, a third pressure sensor; 60, a pressure sensor IV; 61, pressure sensor five; 62, a pressure sensor six; 63, a pressure sensor seven; 64, pressure sensor eight; 65, nine pressure sensors; 66, ten pressure sensors; 67, differential pressure sensor; and 68, an incubator.
FIG. 2 is a graph of permeability measurements for different combinations of reservoir volumes.
In the figure: combinations 1 to 9 are specifically
Detailed Description
The structure of the testing device for permeability of dense rock shown in fig. 1 specifically comprises: the device comprises a holder part for placing and pressurizing a core, a pulse part for providing pulse pressure for the holder part, a gas injection part for providing specified pressure for the pulse part, a temperature control part for controlling the temperature of the holder part and the pulse part, a metering part for measuring the pressure and displacement of the whole system, a vacuum part for vacuumizing the test system, and a data acquisition and processing system for analyzing and acquiring the data of the whole test system.
The holder portion includes a core holder (50) for placing a core, an axial pressure pump (48) for applying an axial pressure to the placed core, and an annular pressure pump (49) for applying a confining pressure to the placed core. The upstream inlet end of the core holder (50) is connected with the pulse part through a valve (17), a valve (14) and a pipeline, and the downstream inlet end of the core holder is connected with the downstream end of the pulse part through a valve (24), a valve (25) and a pipeline.
The metering part comprises pressure sensors (57) and (58) positioned in the pulse part, the measuring ranges are respectively 40MPa and 6MPa, and the pressure sensor with the proper measuring range is selected through the valve (12) to measure the pressure of the chamber; four equally spaced pressure sensors (59), (60), (61) (62) upstream of the gripper section, with respective ranges of 40MPa, 25MPa, 16MPa, 6MPa, the pressure at the upstream end of the pulse being measured by selecting the appropriate range of pressure sensors through valves (15), (16), (17); four symmetrically distributed pressure sensors (63), (64), (65), (66) are arranged at the downstream, the measuring ranges are respectively 6MPa, 16MPa, 25MPa and 40MPa, and the pressure sensor with the proper measuring range is selected through the valves (21), (22) and (23) to measure the pressure at the downstream end of the pulse; pressure sensors (67) connected in parallel at the inlet and outlet ends of the core holder (50), connected in series with the manual valve (19), connected in parallel with the valve (20); a displacement sensor (54) disposed at a downstream end of the core holder (50). The metering section accurately measures pressures, displacements and differential pressures of the pulse section and the holder section.
The pulse part comprises a chamber (46) for storing 50ml upstream of the pulse gas and a chamber (47) for storing 100ml upstream of the pulse gas, and the opening and the closing of the upstream chamber are respectively controlled by valves (11) and (13); a downstream 50ml chamber (56) and a 100ml chamber (55), the opening and closing of which are controlled by valves (26) and (27), respectively. The cavity is made of 316L materials, can bear the pressure of 50MPa, is matched with the core holder (50) for use, can effectively prevent the error of the change of the internal volume caused by high working pressure and high temperature when the design pressure is higher than the working pressure, and improves the data precision.
The gas injection part comprises a nitrogen gas cylinder (31) and a methane gas cylinder (32), the opening and closing of the gas cylinders are controlled through a valve (3) and a valve (4), other gas cylinders required by experiments can be connected to the nitrogen gas cylinder (31) and the methane gas cylinder (32), and the opening and closing of the gas cylinders are controlled through a valve (1); a nitrogen, methane and other gas cylinder pressure gauge (36), a gas booster pump (37) for boosting nitrogen, methane and other gases, a silent air compressor (33) for providing control origin for a gas valve and the gas booster pump (37) in the process, a driving gas pressure reducing valve (34) for adjusting the pressure of driving gas, a driving pressure gauge (35), and air with certain pressure is communicated through a valve (4); the nitrogen storage tank (44), the nitrogen storage tank pressure gauge (38), the nitrogen pressure reducing valve (39) and the nitrogen pressure reducing valve outlet pressure gauge (40) are connected with pressurized nitrogen through the valve (5), and the valve (6) discharges the nitrogen with specified pressure; the methane pressure regulating device comprises a methane storage tank (45), a methane storage tank pressure gauge (41), a methane pressure reducing valve (42) and a methane pressure reducing valve outlet pressure gauge (43), wherein pressurized methane is connected through a valve (7), and methane with specified pressure flows out of a valve (8); the methane part and the nitrogen part are connected in parallel, are independent from each other and do not influence each other, and when an experiment is carried out, one passage is selected to flow into the pulse part through the valve (10), so that initial pressure and subsequent pulse pressure are provided for an experiment system. And when the experiment is finished, the emptying valve (9) can be opened to carry out exhaust treatment on the system.
The temperature control part comprises a thermostat (68), the front of the thermostat (68) is provided with a rotary split door with an observation window, a heat insulation window is arranged in the thermostat, the rotary split door is provided with a high-precision temperature controller, a touch key type power supply, a heating (nickel-chromium wire heater), a fan (brand new high-temperature resistant long-shaft motor and turbofan) switch and the like, and the measuring range is normal temperature to 200 ℃.
The vacuum part comprises a vacuum pump (53), a vacuum meter (52) and a vacuum buffer container (51), the vacuum degree is 6 multiplied by 10 < -2 > Pa, and the discharge capacity of the vacuum pump is 8L/s.
The data acquisition and processing system mainly comprises the formation of pressure signals, the formation of differential pressure signals and an interface with a microcomputer, the system mainly adopts a communication adapter card of Hongge company, the acquisition software is combined to realize the acquisition in time, the system matching software can be operated under a Windows platform, the interface is friendly, and in the data acquisition process, the whole-process graph monitors the changes of pressure, differential pressure and the like. The test precision of the whole system can be ensured, and the intellectualization of each system is realized.
The concrete steps for testing the rock permeability are as follows:
the core is placed in a core holder (50) and both axial and confining pressures are applied to 7 MPa. And the instrument was flushed with nitrogen. To eliminate the temperature error for the experiment, the whole apparatus was placed in an incubator (68) set at 25 ℃. + -. 0.5 ℃.
A first set of experiments was carried out with an upstream 20ml chamber (46) having a volume V1Setting the initial pressure to P0The valves (10), (11), (14), (18), (20), (24), (25), (27) are opened. Because the pore pressure applied by the experiment is less than 6MPa, in order to improve the measurement accuracy, a pressure sensor with the 6MPa measuring range is adopted, and the valves (12), (17) and (21) are opened. After the system pressure is balanced, the valves (14), (20) are closed.
By adjusting the pressure reducing valve (42), the pressure delta p is increased upstream1Closing the valve (10) and recording the reading p of the lower pressure sensor I after the pressure is balanced1. Opening the valve (14) and recording the reading p when the reading of the pressure sensor II is not increased and is equal to the reading of the pressure sensor I2Recording the pressure p after the system has been balanced3(since the gas transport velocity in the pipeline is much higher than the core velocity, this process is extremely short and is completed in a few seconds, and we believe that the core face pressure has not changed before it is captured by the pressure sensor II, so the actual pulse pressure Δ p0Is p2And p0The difference of (d). The first formula for calculating the volume of the pipeline can be obtained according to Boyle's law and the gas equation of state
p1(V1+V3+V5)＝p2(V1+V3+V4+V5)
Closing the valve (24), opening the valve (26), recording the pressure p at that time after the pressure has stabilized4After a stabilization, the valve (24) is opened, after which the reading of the pressure sensor is suddenly increased and then slowly increased, and the critical pressure p is recorded5. (in tight rock, the differential pressure between the upstream and downstream reservoirs is small, the downstream pressure changes slowly, and when the valve (24) is opened, the pressure in the pipe and chamber quickly reaches equilibrium). Obtaining other two calculation formulas for calculating the volume of the pipeline
p3(V1+V5+V7)＝p4(V1+V2+2V5+V7)
p3V6+p4(V1+V2+2V5+V7)＝p5(V1+V2+2V5+V6+V7)
Closing the valve (27) and adjusting the upstream pressure until the initial steady-state pressure is again p0While, the pressure Δ p is also added upstream1And after the pressure is stabilized, opening the valve (14) to finish the second pulse. Then the valves (26), (27) are opened for a third pulse.
A second set of experiments was performed using an upstream 70ml chamber, with a volume V2When the initial pressure p0Repeating the step (3) after stabilization, and recording the index p before the formal pulse6，p7(to ensure that the true pulse pressure is close to or the same, the initial pulse pressure Δ p is applied in view of the increase in the volume of the chamber2Slightly less than Δ p1). By adjusting the valves (26), (27), a second set of triple pulse data is recorded. Obtaining the 4 th calculation formula of the pipeline
p6(V2+V3+V5)＝p7(V2+V3+V4+V5)
The valves (11), (13) are opened and a third set of experiments is performed with the upstream 90ml chamber, when the initial pressure p is reached0Repeating the step (3) after stabilization, and recording the index p before the formal pulse8，p9At this time, the initial pulse pressure Δ p3Slightly less than Δp2Third set of triple pulse data is recorded, again by adjusting valves (26), (27). Obtaining the 5 th calculation formula of the pipeline
p8(V1+V2+V3+2V5)＝p9(V1+V2+V3+V4+2V5)
Wherein, V3The volume of an upstream communication pipeline between the valve (10) and the valve (14) and the volume of a cavity in the pressure sensor I are shown; v4The volume of a communication pipeline from the valve (14) to the left end face of the rock core and the volume of a cavity in the pressure sensor II are represented; v5The volume between the outlet of the chamber (46) and the chamber valve (11) is shown, and since the chamber is manufactured in a customized way and is symmetrical up and down, the volumes between the outlet of the four chambers and the chamber valve are all equal to be V5；V6Is the volume of a communication pipeline between the right end face of the rock core and the valve (24), V7The volume of the communication duct downstream of the valve (24) and the volume of the cavity in the pressure sensor III. From these 5 equations 5 unknowns V can be calculated3，V4，V5，V6，V7。
The permeability of the rock sample was calculated using the formula:
in the formula, pu(t) is the upstream pressure at time t; p is a radical offThe pressure is the equilibrium pressure after the pulse is finished; Δ p is the true pulse pressure, p in each of the three experiments2-p0、p7-p0、p9-p0；VdThe corrected reservoir volume downstream is considered; vuTo account for the corrected volume upstream of the tube volume; alpha is pu(t)-pfThe slope on a semi-logarithmic graph with time t; k is the permeability of the rock sample; a is the cross-sectional area of the rock sample; mu is experimental gasViscosity coefficient of (d); beta is the isothermal compression coefficient of the experimental fluid; l is the length of the rock sample, f is a compressed storage factor and is related to the volume of the upstream and downstream reservoir bodies and the pore volume, and specifically, f is theta 2/(a + b), and a is Vp/Vu,b＝Vp/VdAnd theta is a solution of the transcendental equation tan theta ═ b (a + b) theta/(theta ^ 2-ab).
Claims (7)
1. A tight rock permeability testing device and an application method thereof are characterized by comprising the following devices: a holder part for placing and pressurizing the core, a pulse part for supplying a pulse pressure to the holder part, a gas injection part for supplying a specified pressure to the pulse part, a temperature control part for controlling the temperature of the holder part and the pulse part, a metering part for measuring the pressure and displacement of the pulse part and the holder part, a vacuum part for evacuating the test system, a data acquisition and processing system for analyzing and acquiring data of the entire test system,
the clamp part comprises a core clamp (50) for placing a core, an axial pressure pump (48) axially connected with the core clamp, and an annular pressure pump (49) radially connected with the core clamp; the working pressure of the core clamper (50) is 0-137.9 MPa (20000psi), the working temperature is normal temperature-148.9 ℃ (300 DEG F), the tightness is good, the stratum condition of high temperature and high pressure can be simulated, the measuring ranges of the axial pressure pump (48) and the annular pressure pump (49) are both 0-70MPa, two operation modes of constant flow and constant pressure are provided, the axial pressure and the annular pressure can be accurately and stably controlled in the experimental process,
the pulse part comprises an upstream 20ml chamber (46) and a 70ml chamber (47), a downstream 20ml chamber (56) and a 70ml chamber (55), the chambers are made of 316L and can bear the pressure of 50MPa,
the gas injection part comprises a gas booster pump (37), a mute air compressor (33), a driving gas pressure reducing valve (34), a driving pressure gauge (35), nitrogen, a methane and other gas cylinder pressure gauge (36), a nitrogen storage tank pressure gauge (38), a methane storage tank pressure gauge (41), a nitrogen pressure reducing valve outlet pressure gauge (40) and a methane pressure reducing valve outlet pressure gauge (43), and can store pressurized gas in a nitrogen storage tank (44) and a methane storage tank (45) to obtain specified injection pressure by adjusting the nitrogen pressure reducing valve (39) and the methane pressure reducing valve (42),
the temperature control part comprises a constant temperature box (68), the measuring range is normal temperature to 200 ℃, the temperature control part can be matched with the holder part to simulate the stratum condition of high temperature and high pressure,
the metering part comprises pressure sensors (57-66), and the precision of all the pressure sensors is 0.1%; a differential pressure sensor (67), wherein the static pressure is 4500psi, the measuring range is 0-2 MPa, and the precision is 0.05%; a displacement sensor (54) with a stroke of 10mm and a precision of 0.1 percent, a motion mode of linear displacement and a repeatability of 0.002mm,
the vacuum part comprises a vacuum pump (53), a vacuum gauge (52), and a vacuum buffer container (51) with a vacuum degree of 6 × 10-2Pa, the discharge capacity of a vacuum pump is 8L/s,
the data acquisition and processing system mainly comprises the formation of pressure signals, the formation of differential pressure signals and an interface with a microcomputer, and the system mainly adopts a communication adapter card of Hongge company, realizes timely acquisition by combining acquisition software, ensures the test precision of the whole system and realizes the intellectualization of each system.
2. The tight rock permeability testing device and the application method thereof as claimed in claim 1, wherein the testing device is characterized in that the gripper portion, the pulse portion and the metering portion are controlled by pneumatic valves with good switching performance and good sealing performance, the opening and closing of the pneumatic valves are controlled by air source pressure, and the accuracy of experimental results can be effectively improved by direct control of a computer, so that errors caused by manual operation are avoided.
3. The tight rock permeability test apparatus and method of use thereof according to claim 1, wherein the test apparatus is characterized in that the pressure sensor in the metering section is divided into a plurality of ranges, specifically, valves (12), (17), (21) control the pressure sensors (58), (62), (63); the valves (16) and (22) control pressure sensors (61) and (64) with 16MPa measuring range; the valves (15) and (23) control pressure sensors (60) and (65) with 25MPa measuring range; the appropriate sensor can be selected according to the specific experimental conditions, so that the reading error is smaller, and the experimental data is more accurate.
4. The tight rock permeability testing device and the application method thereof according to claim 1, wherein the testing device is characterized in that the gas injection part can simultaneously store two gases which are respectively stored in the storage tank (44) and the storage tank (45), and the gas replacement experiment is realized according to the experiment sequence; or after one gas finishes the experiment, closing the valve (10), vacuumizing the system by using a vacuum pump (53), and then adopting the other storage tank gas to carry out the experiment, thereby realizing the research on the change of the permeability of two different gases when the gases pass through the rock core.
5. The tight rock permeability testing apparatus and the application method thereof according to claim 1, wherein the testing apparatus is characterized in that compared with the conventional permeability testing apparatus, an upstream pressure testing apparatus is added to the metering part, so that the pipeline volume can be measured during the tight rock permeability testing process, and the reservoir volume and the actual pulse pressure can be corrected.
6. The tight rock permeability testing device and the application method thereof as claimed in claim 1, wherein the specific application method for testing the tight rock permeability is as follows:
1) placing the core in a core holder (50), applying axial pressure and confining pressure to 7Mpa, flushing the instrument with nitrogen gas, placing the whole device in a thermostat (68) at 25 + -0.5 deg.C to eliminate temperature error,
a first set of experiments was carried out with an upstream 20ml chamber (46) having a volume V1Setting the initial pressure to P0Opening valves (10), (11), (14), (18), (20), (24), (25) and (27), and because the pore pressure applied by the experiment is less than 6MPa, in order to improve the measurement accuracy, adopting a pressure sensor with a 6MPa range, opening valves (12), (17) and (21), and closing valves (14) and (20) after the system pressure is balanced;
2) by adjusting the pressure reducing valve (42), the pressure delta p is increased upstream1Closing ofThe valve (10) is closed, and the reading p of the lower pressure sensor I is recorded after the pressure is balanced1Opening the valve (14) and recording the reading p when the reading of the pressure sensor II is not increased and is equal to the reading of the pressure sensor I2Recording the pressure p after the system has been balanced3(since the gas transport velocity in the pipeline is much higher than the core velocity, this process is extremely short and is completed in a few seconds, and we believe that the core face pressure has not changed before it is captured by the pressure sensor II, so the actual pulse pressure Δ p0Is p2And p0The difference) of (a) and (b) can obtain a first formula for calculating the volume of the pipeline according to Boyle's law and a gas state equation;
3) closing the valve (24), opening the valve (26), recording the pressure p at that time after the pressure has stabilized4After a stabilization, the valve (24) is opened, after which the reading of the pressure sensor is suddenly increased and then slowly increased, and the critical pressure p is recorded5(when the differential pressure of the upper reservoir and the lower reservoir in the tight rock is small, the pressure change of the lower reservoir is slow, and when the valve (24) is opened, the pressure in the pipeline and the cavity can quickly reach balance), and other two calculation formulas for calculating the volume of the pipeline are obtained;
4) closing the valve (27) and adjusting the upstream pressure until the initial steady-state pressure is again p0While, the pressure Δ p is also added upstream1After the pressure has stabilized, opening the valve (14) to complete the second pulse, and then opening the valves (26), (27) to perform a third pulse;
5) a second set of experiments was performed using an upstream 70ml chamber, with a volume V2When the initial pressure p0Repeating the step (3) after stabilization, and recording the index p before the formal pulse6，p7(to ensure that the true pulse pressure is close to or the same, the initial pulse pressure Δ p is applied in view of the increase in the volume of the chamber2Slightly less than Δ p1) Recording a second set of triple pulse data by adjusting valves (26), (27); obtaining a 4 th calculation formula of the pipeline;
6) the valves (11), (13) are opened and a third set of experiments is performed with the upstream 90ml chamber, when the initial pressure p is reached0Repeating the step (3) after the stabilization,register the index p before the official pulse8，p9At this time, the initial pulse pressure Δ p3Slightly less than Δ p2Third group of third pulse data is recorded again by adjusting valves (26), (27) to obtain the 5 th calculation formula of the pipeline,
the permeability of the rock sample was calculated using the formula:
in the formula, pu(t) is the upstream pressure at time t; p is a radical offThe pressure is the equilibrium pressure after the pulse is finished; Δ p is the true pulse pressure, p in each of the three experiments2-p0、p7-p0、p9-p0；VdThe corrected reservoir volume downstream is considered; vuTo account for the corrected volume upstream of the tube volume; alpha is pu(t)-pfThe slope on a semi-logarithmic graph with time t; k is the permeability of the rock sample; a is the cross-sectional area of the rock sample; mu is the viscosity coefficient of the experimental gas; beta is the isothermal compression coefficient of the experimental fluid; l is the length of the rock sample; f is a compressed storage factor which is related to the volume of the upstream and downstream storage layer bodies and the pore volume, and the specific calculation method comprises the following steps: f ═ θ ^2/(a + b), a ═ Vp/Vu,b＝Vp/Vd,
Is a transcendental equation
The solution of (1).
7. The tight rock permeability testing device and the application method thereof according to claim 1, and the application method thereof according to claim 6, characterized in that the pulse part comprises an upstream 20ml chamber (46) and a 70ml chamber (47), and a downstream 20ml chamber (56) and a 70ml chamber (55), and the combination of 3 groups of 9 different reservoir volumes can be realized by adjusting valves (11), (13), (26) and (27), so as to obtain 9 different f values, so that the influence of different reservoir combinations on the permeability measurement can be studied.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112855089A (en) * | 2021-02-01 | 2021-05-28 | 重庆科技学院 | Application method for calculating effective permeability of two-dimensional sand-packed model |
| CN114295528A (en) * | 2021-12-29 | 2022-04-08 | 西安建筑科技大学 | Experimental system and research method for researching gas permeability characteristics of unsaturated soil body |
| CN114645698A (en) * | 2022-05-19 | 2022-06-21 | 山东石油化工学院 | Low-permeability reservoir pressure flooding water injection physical simulation test system and method |
| CN117538236A (en) * | 2024-01-08 | 2024-02-09 | 中国地质大学（武汉） | Shale overburden pore infiltration combined measurement device and method |
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2020
- 2020-08-25 CN CN202010862886.6A patent/CN111879680A/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112855089A (en) * | 2021-02-01 | 2021-05-28 | 重庆科技学院 | Application method for calculating effective permeability of two-dimensional sand-packed model |
| CN114295528A (en) * | 2021-12-29 | 2022-04-08 | 西安建筑科技大学 | Experimental system and research method for researching gas permeability characteristics of unsaturated soil body |
| CN114645698A (en) * | 2022-05-19 | 2022-06-21 | 山东石油化工学院 | Low-permeability reservoir pressure flooding water injection physical simulation test system and method |
| CN117538236A (en) * | 2024-01-08 | 2024-02-09 | 中国地质大学（武汉） | Shale overburden pore infiltration combined measurement device and method |
| CN117538236B (en) * | 2024-01-08 | 2024-04-09 | 中国地质大学（武汉） | Shale overburden pore infiltration combined measurement device and method |
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