CN107014731B - A kind of drive of hypotonic rock gas-liquid two pressure pulse decaying permeability test method - Google Patents

Abstract

A kind of hypotonic rock gas-liquid two drives pressure pulse decaying infiltration experiment device and method, device includes that gas-liquid two drives formula fluid charging assembly, confining pressure pump, pressure chamber, differential pressure pickup, pressure sensor, several shut-off valves, pressure regulator valve, vacuum pump, auxiliary heater and water bath with thermostatic control, gas-liquid two drives formula fluid charging assembly and had not only been able to satisfy liquid output but also had been able to satisfy gas output, in hypotonic rock permeability test, can biggish pressure difference actively be established in the upstream and downstream of hypotonic rock, mentality of designing based on pressure pulse damped method simultaneously, it is capable of the permeability and infiltration coefficient of rapid survey hypotonic rock；Experimental rig manifold volume established by the present invention is smaller, it is less than 300ml through practical measuring and calculating, the influence that environmental temperature fluctuation will generate manifold volume can be effectively reduced, simultaneously in conjunction with water bath with thermostatic control and auxiliary heater, the accurate control to environment temperature can be realized again, the influence that environmental temperature fluctuation will generate manifold volume is further decreased, measurement accuracy is finally improved.

Description

A low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test method

technical field

The invention belongs to the technical field of low permeability rock permeability test, in particular to a low permeability rock gas-liquid two-drive pressure pulse attenuation permeability test device and method.

Background technique

Shale gas is a kind of unconventional energy. It exists in source rocks in various states. About 50% of the free gas in shale gas can move freely, and the remaining gas mostly exists in adsorption state and dissolved state. In addition, due to the porous and low permeability characteristics of the reservoir matrix, it is difficult for shale gas to migrate in the reservoir matrix and be difficult to recover. The permeability of shale is an important index parameter to characterize the ease of shale gas migration. Accurate measurement of shale permeability has an important impact on well logging evaluation and productivity prediction.

At present, the traditional pressure-difference rock steady-state permeability test is only suitable for rocks with high permeability, and for low-permeability rocks such as shale, in order to measure the permeability, the establishment of Darcy steady-state flow requires at least It takes several days or even weeks, and the upstream and downstream flow changes are small, and the accuracy level of the existing flowmeter is difficult to meet the measurement requirements. Therefore, low-permeability rocks are greatly limited in the traditional pressure-difference rock steady-state permeability test.

Furthermore, in the process of measuring the permeability of low-permeability rocks such as shale, temperature is also one of the important environmental factors that affect the measurement accuracy. Due to the large pipeline volume of the existing test device, it can be known from Boyle's law that under high pressure conditions Under low ambient temperature fluctuations, small fluctuations in ambient temperature will have a great impact on the volume of the pipeline, which will indirectly affect the control and measurement of parameters such as pressure and flow. Therefore, how to reduce the pipeline volume of the measuring device is also an urgent problem to be solved.

Therefore, for the problems of long measurement time, large pipeline volume and low measurement accuracy in the existing low-permeability rock permeability test, it is urgent to develop a new low-permeability rock permeability test device and method.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the prior art, the present invention provides a low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device and method, which has the characteristics of short measurement time, small pipeline volume and high measurement accuracy.

In order to achieve the above purpose, the present invention adopts the following technical scheme: a low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device, comprising a gas-liquid two-drive fluid loading assembly, a confining pressure pump, a pressure chamber, a differential pressure sensor, a pressure The sensor, the first cut-off valve, the second cut-off valve, the third cut-off valve, the fourth cut-off valve, the fifth cut-off valve, the first pressure regulating valve, the second pressure regulating valve and the constant temperature water bath are respectively set on the pressure chamber. There are confining pressure inlet, confining pressure outlet, pulse pressure inlet and pulse pressure outlet, and a temperature measuring thermocouple is installed in the pressure chamber;

The fluid outlet of the gas-liquid two-drive fluid loading assembly communicates with the pulse pressure inlet of the pressure chamber through the first cut-off valve and the second cut-off valve in sequence, and the other way passes through the first cut-off valve, the third cut-off valve, the pressure The sensor and the fourth stop valve are communicated with the pulse pressure outlet of the pressure chamber;

The outlet of the confining pressure pump is communicated with the confining pressure inlet of the pressure chamber through the fifth stop valve, and the confining pressure outlet of the pressure chamber is communicated with the first pressure regulating valve;

One end of the differential pressure sensor is connected to the pipeline between the pressure sensor and the fourth cut-off valve, and the other end of the differential pressure sensor is connected to the pipeline between the second cut-off valve and the third cut-off valve;

The second pressure regulating valve is connected to the pipeline between the pressure sensor and the third shut-off valve;

The pressure chamber, the differential pressure sensor, the pressure sensor, the first shut-off valve, the second shut-off valve, the third shut-off valve, the fourth shut-off valve, the fifth shut-off valve, the first pressure regulating valve, the second pressure regulating valve and the same The connecting pipes between them are all located in a constant temperature water bath.

The gas-liquid two-drive fluid loading assembly includes a gas cylinder, a water tank, a booster pump, a water pump, a pressure reducing valve, a sixth stop valve, a seventh stop valve, a displacement pump, an eighth stop valve, a pressure relief valve and an auxiliary heater;

The gas cylinder is communicated with the inlet of the displacement pump through the booster pump, the pressure reducing valve and the sixth shut-off valve in turn, and the water tank is communicated with the inlet of the displacement pump through the water pump and the seventh shut-off valve in turn, and the displacement pump is communicated with the inlet of the displacement pump in turn. The outlet of the valve is communicated with the first cut-off valve through the eighth cut-off valve and the auxiliary heater in turn;

The pressure relief valve is connected to the pipeline between the eighth cut-off valve and the auxiliary heater, and a pressure gauge is installed on the pipeline between the eighth cut-off valve and the auxiliary heater.

The gas-liquid two-drive fluid loading assembly further includes a vacuum pump and a ninth cut-off valve, the ninth cut-off valve is connected to the pipeline between the eighth cut-off valve and the auxiliary heater, and the suction port of the vacuum pump is connected to the ninth cut-off valve Pass.

A first constant volume high pressure container is connected to the pipeline between the second stop valve and the third stop valve, and a second constant volume high pressure container is connected to the pipeline between the pressure sensor and the third stop valve.

A third constant-volume high-pressure vessel is connected in series with the first constant-volume high-pressure vessel, and a tenth stop valve is arranged between the first constant-volume high-pressure vessel and the third constant-volume high-pressure vessel; A fourth constant volume high pressure container is connected in series, and an eleventh stop valve is arranged between the second constant volume high pressure container and the fourth constant volume high pressure container.

A low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test method adopts the low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device, comprising the following steps:

Step 1: Encapsulate the rock sample

First clean the surface of the rock sample, then place the rock sample between two pressure plates, and install an orifice plate between the rock sample and the pressure plate, then put the heat shrink sleeve on the outside of the rock sample, the orifice plate and the pressure plate, and finally heat and shrink it. Shrink the sleeve until the rock sample, orifice plate and pressure plate are wrapped and sealed by the heat shrink sleeve;

Step 2: Install the rock sample

The packaged rock sample is placed in the pressure chamber, and the pulse pressure inlet of the pressure chamber is connected to the rock sample through the pressure plate on one side of the rock sample, and the pulse pressure outlet of the pressure chamber is connected to the rock sample through the other side pressure plate, and then the pressure chamber is closed;

Step 3: Vacuum

Open the ninth globe valve, close the eighth globe valve and pressure relief valve, open the first globe valve, the second globe valve, the third globe valve, the fourth globe valve, the tenth globe valve and the eleventh globe valve, close the first globe valve, the second globe valve, the third globe valve, the fourth globe valve, the tenth globe valve and the eleventh globe valve, Five stop valves, the first pressure regulating valve and the second pressure regulating valve, and then start the vacuum pump to vacuumize the pressure chamber and connecting pipeline;

Step 4: Confining pressure loading

Open the fifth stop valve and the first pressure regulating valve, and then start the confining pressure pump to load the rock sample in the pressure chamber with confining pressure;

Step 5: Saturate the rock sample

Open the eighth stop valve, and select liquid or gas to saturate the rock sample under the initial set pressure value;

When the liquid is selected to saturate the rock sample, close the sixth stop valve, open the seventh stop valve, and then start the water pump and the displacement pump until the liquid saturation of the rock sample is completed;

When gas is selected for rock sample saturation, close the seventh stop valve, open the sixth stop valve, then open the gas cylinder, start the booster pump and the displacement pump, until the gas saturation of the rock sample is completed;

Step 6: Pulse Pressure Loading

Close the second cut-off valve and the third cut-off valve, continue to output fluid through the displacement pump until the pulse pressure loading of the upstream pipeline is completed, and select the number of constant-volume high-pressure containers to be connected according to actual needs;

Step 7: Release Pulse Pressure

Open the second shut-off valve to release the pulse pressure of the upstream pipeline until the upstream and downstream pressures of the rock sample return to balance;

Step 8: Data collection and permeability calculation

Collect data through the differential pressure sensor and pressure sensor, and transmit the data to the computer, generate the logarithmic curve of the pressure difference with time in the computer, and calculate the permeability and permeability coefficient at the same time, and the data acquisition time is when the upstream and downstream pressures return to equilibrium 10%～50% of the time, the time range is 20s～1.5h;

Step 9: Pore Pressure Unloading

Open the third shut-off valve, first unload the pressure in the pipeline to below 50Pa through the displacement pump, and then release the fluid in the pipeline through the second pressure regulating valve to complete the unloading of the pore pressure;

Step 10: Confining pressure unloading

First, the confining pressure in the pressure chamber is unloaded to below 50Pa through the confining pressure pump, and then the fluid in the pressure chamber is released through the first pressure regulating valve to complete the unloading of the confining pressure.

In step 4, the loaded confining pressure is determined by calculation, and the calculation formula is as follows:

where P _c is the confining pressure, μ is the Poisson’s ratio, D is the sampling depth, and P _gra is the pressure gradient.

In step 8, the permeability and permeability coefficient are calculated by the following formulas:

In the formula, P _u is the upstream pressure, _Pe is the pressure after the upstream and downstream balance, ΔP is the pulse pressure, V ₁ is the upstream pipeline volume, V ₂ is the downstream pipeline volume, t is the decay time of the pulse pressure, and θ is the upstream The slope of the change curve of pressure with time, K is the permeability coefficient, A is the cross-sectional area of the rock sample, μ _f is the fluid viscosity coefficient, C _f is the fluid compressibility coefficient, L is the length of the rock sample, k is the permeability, ρ is the fluid density , g is the acceleration of gravity.

Beneficial effects of the present invention:

Compared with the traditional pressure difference method rock steady-state permeability test, the invention completely satisfies the low permeability rock permeability test, and can actively establish a large pressure difference between the upstream and downstream of the low permeability rock. The idea is to realize the rapid measurement of permeability and permeability coefficient of low permeability rock.

The invention establishes a gas-liquid two-drive fluid output mode, only needs the same set of test equipment, which can satisfy both the liquid-based low-permeability rock permeability test and the gas-based low-permeability rock permeability test, effectively expanding the test device scope of use.

The pipeline volume of the test device established by the present invention is smaller, which is less than 300ml according to actual measurement, which effectively reduces the influence of environmental temperature fluctuation on the pipeline volume. At the same time, combined with a constant temperature water bath and an auxiliary heater, the The precise control of the ambient temperature further reduces the impact of ambient temperature fluctuations on the volume of the pipeline, and ultimately improves the measurement accuracy.

Description of drawings

1 is a schematic diagram of a low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device of the present invention;

Figure 2 is a schematic diagram of the installation of the rock sample and the pressure chamber;

In the figure, 1—confining pressure pump, 2—pressure chamber, 3—pressure difference sensor, 4—pressure sensor, 5—first globe valve, 6—second globe valve, 7—third globe valve, 8—fourth globe valve Globe valve, 9—fifth globe valve, 10—first pressure regulating valve, 11—second pressure regulating valve, 12—constant temperature water bath, 13—gas cylinder, 14—water tank, 15—booster pump, 16—water pump, 17—relief valve, 18—sixth globe valve, 19—seventh globe valve, 20—displacement pump, 21—eighth globe valve, 22—pressure relief valve, 23—auxiliary heater, 24—pressure gauge, 25—vacuum pump, 26—the ninth stop valve, 27—the first constant volume high pressure vessel, 28—the second constant volume high pressure vessel, 29—the third constant volume high pressure vessel, 30—the fourth constant volume high pressure vessel, 31—the first constant volume high pressure vessel Ten globe valve, 32—Eleventh globe valve, 33—rock sample, 34—pressing plate, 35—orifice plate, 36—heat shrinkable sleeve.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device includes a gas-liquid two-drive fluid loading assembly, a confining pressure pump 1, a pressure chamber 2, a differential pressure sensor 3, a pressure sensor 4, The first shut-off valve 5, the second shut-off valve 6, the third shut-off valve 7, the fourth shut-off valve 8, the fifth shut-off valve 9, the first pressure regulating valve 10, the second pressure regulating valve 11 and the constant temperature water bath 12 are located here. The pressure chamber 2 is respectively provided with a confining pressure inlet, a confining pressure outlet, a pulse pressure inlet and a pulse pressure outlet, and a temperature measuring thermocouple is installed in the pressure chamber 2;

The fluid outlet of the gas-liquid two-drive fluid loading assembly communicates with the pulse pressure inlet of the pressure chamber 2 through the first cut-off valve 5 and the second cut-off valve 6 in sequence, and the other way passes through the first cut-off valve 5 and the third stop valve. The cut-off valve 7, the pressure sensor 4 and the fourth cut-off valve 8 are communicated with the pulse pressure outlet of the pressure chamber 2;

The outlet of the confining pressure pump 1 is communicated with the confining pressure inlet of the pressure chamber 2 through the fifth stop valve 9, and the confining pressure outlet of the pressure chamber 2 is communicated with the first pressure regulating valve 10;

One end of the differential pressure sensor 3 is connected on the pipeline between the pressure sensor 4 and the fourth stop valve 8, and the other end of the differential pressure sensor 3 is connected on the pipeline between the second stop valve 6 and the third stop valve 7;

The second pressure regulating valve 11 is connected to the pipeline between the pressure sensor 4 and the third shut-off valve 7;

The pressure chamber 2, differential pressure sensor 3, pressure sensor 4, first cut-off valve 5, second cut-off valve 6, third cut-off valve 7, fourth cut-off valve 8, fifth cut-off valve 9, first pressure regulating valve 10. The second pressure regulating valve 11 and the connecting pipeline therebetween are located in the constant temperature water bath 12 .

The gas-liquid two-drive fluid loading assembly includes a gas cylinder 13, a water tank 14, a booster pump 15, a water pump 16, a pressure reducing valve 17, a sixth stop valve 18, a seventh stop valve 19, a displacement pump 20, and an eighth stop valve. Stop valve 21, pressure relief valve 22 and auxiliary heater 23;

The gas cylinder 13 is connected to the inlet of the displacement pump 20 through the booster pump 15, the pressure reducing valve 17 and the sixth stop valve 18 in sequence, and the water tank 14 is connected to the displacement pump through the water pump 16 and the seventh stop valve 19 in sequence. The inlet of 20 is communicated with, and the outlet of the displacement pump 20 is communicated with the first shut-off valve 5 through the eighth shut-off valve 21 and the auxiliary heater 23 in turn;

The pressure relief valve 22 is connected to the pipeline between the eighth stop valve 21 and the auxiliary heater 23 , and a pressure gauge 24 is installed on the pipeline between the eighth stop valve 21 and the auxiliary heater 23 .

The gas-liquid two-drive fluid loading assembly further includes a vacuum pump 25 and a ninth cut-off valve 26. The ninth cut-off valve 26 is connected to the pipeline between the eighth cut-off valve 21 and the auxiliary heater 23. The suction port of the vacuum pump 25 It communicates with the ninth shut-off valve 26 .

A first constant-volume high-pressure container 27 is connected to the pipeline between the second cut-off valve 6 and the third cut-off valve 7 , and a second constant-volume high-pressure container 27 is connected to the pipeline between the pressure sensor 4 and the third cut-off valve 7 . Constant volume high pressure vessel 28 . In this embodiment, the capacities of the first constant-volume high-pressure container 27 and the second constant-volume high-pressure container 28 are both 100ml;

A third constant-volume high-pressure vessel 29 is connected in series with the first constant-volume high-pressure vessel 27, and a tenth stop valve 31 is arranged between the first constant-volume high-pressure vessel 27 and the third constant-volume high-pressure vessel 29; the second constant-volume high-pressure vessel 29 A fourth constant-volume high-pressure vessel 30 is connected in series with the constant-volume high-pressure vessel 28 , and an eleventh shut-off valve 32 is provided between the second constant-volume high-pressure vessel 28 and the fourth constant-volume high-pressure vessel 30 . In this embodiment, the capacities of the third constant volume high pressure container 29 and the fourth constant volume high pressure container 30 are both 1000ml;

A low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test method adopts the low-permeability rock gas-liquid two-drive pressure pulse attenuation penetration test device, comprising the following steps:

Step 1: Encapsulate the rock sample

First clean the surface of the rock sample 33, then place the rock sample 33 between the two pressing plates 34, and install the orifice plate 35 between the rock sample 33 and the pressing plate 34, and then set the heat shrinkable sleeve 36 on the rock sample 33 and the orifice plate. 35 and the outside of the pressure plate 34, and finally heat the heat shrinkable sleeve 36 to shrink it until the rock sample 33, the orifice plate 35 and the pressure plate 34 are wrapped and sealed by the heat shrinkable sleeve 36; in this embodiment, the rock sample 33 is a columnar rock sample with a diameter of The length is 25mm;

Step 2: Install the rock sample

As shown in Figure 2, the packaged rock sample 33 is placed in the pressure chamber 2, and the pulse pressure inlet of the pressure chamber 2 is connected to the rock sample 33 through the pressure plate 34 on the side of the rock sample 33, and the pulse pressure outlet of the pressure chamber 2 passes through The other side pressing plate 34 is connected to the rock sample 33, and then the pressure chamber 2 is closed;

Step 3: Vacuum

Open the ninth stop valve 26, close the eighth stop valve 21 and the pressure relief valve 22, open the first stop valve 5, the second stop valve 6, the third stop valve 7, the fourth stop valve 8, the tenth stop valve 31 and The eleventh cut-off valve 32 closes the fifth cut-off valve 9, the first pressure regulating valve 10 and the second pressure regulating valve 11, and then starts the vacuum pump 25 to vacuumize the pressure chamber 2 and the connecting pipeline; in this embodiment , the vacuuming time is 10min, and the ultimate vacuum pressure reaches 50Pa ~ 100Pa;

Step 4: Confining pressure loading

Open the fifth stop valve 9 and the first pressure regulating valve 10, then start the confining pressure pump 1, and load the rock sample 33 in the pressure chamber 2 with confining pressure; wherein, the confining pressure loaded is determined by calculation, and the calculation formula is as follows:

In the formula, P _c is the confining pressure, μ is the Poisson’s ratio, D is the sampling depth, and P _gra is the pressure gradient; in this embodiment, the Poisson’s ratio μ is 0.2 to 0.22, the sampling depth D is 2500 m, and the pressure gradient P _gra is 22.6MPa/km, and the calculated confining pressure P _c is 25MPa～30MPa;

Step 5: Saturate the rock sample

Open the eighth stop valve 21, and select liquid or gas to saturate the rock sample 33 under the initial set pressure value;

When selecting liquid to saturate the rock sample 33, close the sixth stop valve 18, open the seventh stop valve 19, and then start the water pump 16 and the displacement pump 20 until the liquid saturation of the rock sample 33 is completed; in this embodiment, the liquid is Water, the initial set pressure value is 10MPa, the saturation time is 3 days, and the saturation pressure is 10MPa;

When selecting gas to saturate the rock sample 33, close the seventh stop valve 19, open the sixth stop valve 18, then open the gas cylinder 13, start the booster pump 15 and the displacement pump 20, until the gas saturation of the rock sample 33 is completed; In this embodiment, the gas is nitrogen, the initial set pressure is 8MPa, the saturation time is 8 hours, and the saturation pressure is 10MPa;

Step 6: Pulse Pressure Loading

Close the second cut-off valve 6 and the third cut-off valve 7, continue to output fluid through the displacement pump 20 until the pulse pressure loading of the upstream pipeline is completed, and select the number of constant-volume high-pressure containers to be connected according to actual needs; in this embodiment , close the tenth stop valve 31 and the eleventh stop valve 32, and only connect the first constant volume high pressure container 27 and the second constant volume high pressure container 28;

Step 7: Release Pulse Pressure

Open the second shut-off valve 6 to release the pulse pressure of the upstream pipeline until the upstream and downstream pressures of the rock sample 33 return to equilibrium;

Step 8: Data collection and permeability calculation

The data is collected by the differential pressure sensor 3 and the pressure sensor 4, and the data is transmitted to the computer. The logarithmic curve of the pressure differential with time is generated in the computer, and the permeability and permeability coefficient are calculated at the same time, and the data acquisition time is the upstream and downstream pressure. 10% to 50% of the time to restore equilibrium, and the time range is 20s to 1.5h; among them, the permeability and permeability coefficient are calculated by the following formulas:

In the formula, P _u is the upstream pressure, _Pe is the pressure after the upstream and downstream balance, ΔP is the pulse pressure, V ₁ is the upstream pipeline volume, V ₂ is the downstream pipeline volume, t is the decay time of the pulse pressure, and θ is the upstream The slope of the change curve of pressure with time, K is the permeability coefficient, A is the cross-sectional area of the rock sample, μ _f is the fluid viscosity coefficient, C _f is the fluid compressibility coefficient, L is the length of the rock sample, k is the permeability, ρ is the fluid density , g is the acceleration of gravity;

When liquid is used to saturate the rock sample 33, in this embodiment, the upstream pressure P _u is 10.2 MPa, the upstream and downstream balanced pressure _Pe is 10.1 MPa, the pulse pressure ΔP is 0.2 MPa, and the upstream pipeline volume V ₁ is 2× 10 ^-6 m ³ , the downstream pipeline volume V ₂ is 2×10 ^-6 m ³ , the decay time t of the pulse pressure is 2.4×10 ² s, the slope θ of the upstream pressure change curve with time is 38°, and the permeability coefficient K is 9.8×10 ^-10 m/s, the cross-sectional area A of the rock sample is 4.909×10 ^-4 m ² , the fluid viscosity μ _f is 1×10 ^-3 pa·s, and the fluid compressibility C _f is 4.2×10 ^{- 10} Pa ^-1 , the rock sample length L is 25mm, the permeability k is 1×10 ^-16 m ² , the fluid density ρ is 1×10 ³ kg/m ³ , and the gravitational acceleration g is 9.8m/s ² ;

When gas is used to saturate the rock sample 33, in this embodiment, the upstream pressure P _u is 10.2 MPa, the upstream and downstream balanced pressure _Pe is 10.1 MPa, the pulse pressure ΔP is 0.2 MPa, and the upstream pipeline volume V ₁ is 2× 10 ^-6 m ³ , the downstream pipeline volume V ₂ is 2×10 ^-6 m ³ , the decay time t of the pulse pressure is 5.3×10 ³ s, the slope θ of the upstream pressure change curve with time is 32°, and the permeability coefficient K is 1.244×10 ^-11 m/s, the cross-sectional area A of the rock sample is 4.909×10 ^-4 m ² , the fluid viscosity μ _f is 1.78×10 ^{- 5} pa·s, and the fluid compressibility C _f is 9.8×10 ^{- 7} Pa ^-1 , the length L of the rock sample is 25mm, the permeability k is 2×10 ^-17 m ² , the fluid density ρ is 1.13kg/m ³ , and the gravitational acceleration g is 9.8m/s ² ;

Step 9: Pore Pressure Unloading

Open the third stop valve 7, first unload the pressure in the pipeline to below 50Pa through the displacement pump 20, and then release the fluid in the pipeline through the second pressure regulating valve 11 to complete the unloading of the pore pressure;

Step 10: Confining pressure unloading

First, the confining pressure in the pressure chamber 2 is unloaded to below 50 Pa through the confining pressure pump 1, and then the fluid in the pressure chamber is released through the first pressure regulating valve 10 to complete the unloading of the confining pressure.

The solutions in the embodiments are not intended to limit the scope of the patent protection of the present invention, and all equivalent implementations or modifications that do not depart from the present invention are included in the scope of the patent of this case.

Claims (3)

1. a kind of hypotonic rock gas-liquid two drives pressure pulse decaying permeability test method, uses hypotonic rock gas-liquid two and drive pressure Impulse attenuation infiltration experiment device, experimental rig include that gas-liquid two drives formula fluid charging assembly, confining pressure pump, pressure chamber, pressure difference biography Sensor, pressure sensor, the first shut-off valve, the second shut-off valve, third shut-off valve, the 4th shut-off valve, the 5th shut-off valve, first are adjusted Pressure valve, the second pressure regulator valve and water bath with thermostatic control are respectively equipped with confining pressure entrance in the pressure chamber, confining pressure exports, pulse enters Mouth and pulse outlet, add temperature thermocouple in pressure chamber；The gas-liquid two drives the fluid of formula fluid charging assembly Outlet passes sequentially through the first shut-off valve and the second shut-off valve all the way and is connected with the pulse entrance of pressure chamber, and another way is successively It is connected by the first shut-off valve, third shut-off valve, pressure sensor and the 4th shut-off valve with the outlet of the pulse of pressure chamber； The outlet of the confining pressure pump is connected by the 5th shut-off valve with the confining pressure entrance of pressure chamber, the confining pressure outlet and first of pressure chamber Pressure regulator valve is connected；Described differential pressure pickup one end is connected on the pipeline between pressure sensor and the 4th shut-off valve, pressure difference The sensor other end is connected on the pipeline between the second shut-off valve and third shut-off valve；Second pressure regulator valve is connected to pressure On pipeline between sensor and third shut-off valve；The pressure chamber, differential pressure pickup, pressure sensor, the first shut-off valve, Two shut-off valves, third shut-off valve, the 4th shut-off valve, the 5th shut-off valve, the first pressure regulator valve, the second pressure regulator valve and its between connecting tube Road is respectively positioned in water bath with thermostatic control；It includes gas cylinder, water tank, booster pump, water pump, decompression that the gas-liquid two, which drives formula fluid charging assembly, Valve, the 6th shut-off valve, the 7th shut-off valve, displacement pump, the 8th shut-off valve, relief valve and auxiliary heater；The gas cylinder successively leads to It crosses booster pump, pressure reducing valve and the 6th shut-off valve to be connected with the entrance that displacement pumps, the water tank passes sequentially through water pump and the 7th section Only valve is connected with the entrance that displacement pumps, and the outlet of displacement pump passes sequentially through the 8th shut-off valve and auxiliary heater and the first cut-off Valve is connected；The relief valve is connected on the pipeline between the 8th shut-off valve and auxiliary heater, the 8th shut-off valve with it is auxiliary It helps on the pipeline between heater and pressure gauge is installed；It further includes vacuum pump and the 9th that the gas-liquid two, which drives formula fluid charging assembly, Shut-off valve, the 9th shut-off valve are connected on the pipeline between the 8th shut-off valve and auxiliary heater, the air entry of vacuum pump and Nine shut-off valves are connected；The high pressure-volume of the first constant volume is connected on pipeline between second shut-off valve and third shut-off valve Device is connected with the second constant volume high-pressure bottle on the pipeline between the pressure sensor and third shut-off valve；Described first is fixed Hold and be in series with third constant volume high-pressure bottle on high-pressure bottle, is set between the first constant volume high-pressure bottle and third constant volume high-pressure bottle It is equipped with the tenth shut-off valve；It is in series with the 4th constant volume high-pressure bottle on the second constant volume high-pressure bottle, in the high pressure-volume of the second constant volume The 11st shut-off valve is provided between device and the 4th constant volume high-pressure bottle；It is characterized by: test method includes the following steps:

Step 1: encapsulation rock sample

Rock sample surface is cleaned first, then rock sample is placed between two pressing plates, while orifice plate being installed between rock sample and pressing plate, so Thermal shrinkable sleeve is sleeved on the outside of rock sample, orifice plate and pressing plate afterwards, finally heated thermal shrinkable sleeve makes its contraction, until rock sample, orifice plate and pressure Plate is by thermal shrinkable sleeve environmental sealing；

Step 2: installation rock sample

Rock sample after encapsulation is placed in pressure chamber, while the pulse entrance of pressure chamber accesses rock by one side plate of rock sample The pulse outlet of sample, pressure chamber accesses rock sample by another side plate, then confining pressure room；

Step 3: it vacuumizes

The 9th shut-off valve is opened, the 8th shut-off valve and relief valve are closed, opens the first shut-off valve, the second shut-off valve, third cut-off Valve, the 4th shut-off valve, the tenth shut-off valve and the 11st shut-off valve close the 5th shut-off valve, the first pressure regulator valve and the second pressure regulator valve, Then start vacuum pump, pressure chamber and connecting line are carried out vacuumizing operation；

Step 4: confining pressure load

The 5th shut-off valve and the first pressure regulator valve are opened, confining pressure pump is then started, confining pressure load is carried out to the rock sample of pressure chamber；

Step 5: rock sample saturation

The 8th shut-off valve is opened, under initial setup pressure value, liquid or gas is selected to be saturated rock sample；

When selecting liquid to carry out rock sample saturation, the 6th shut-off valve is closed, opens the 7th shut-off valve, then starts water pump and displacement Pump, the hold-up until completing rock sample；

When selecting gas to carry out rock sample saturation, the 7th shut-off valve is closed, the 6th shut-off valve is opened, is then turned on gas cylinder, is started Booster pump and displacement pump, the gas saturation until completing rock sample；

Step 6: pulse load

The second shut-off valve and third shut-off valve are closed, fluid is continued to output by displacement pump, until completing the pulse of upstream Pressure-loaded, and the constant volume high-pressure bottle quantity of access is selected according to actual needs；

Step 7: release pulse

The second shut-off valve is opened, realizes the pulse release of upstream, until the upstream and downstream pressure recovery of rock sample balances；

Step 8: data acquisition and computing permeability

Data are acquired by differential pressure pickup and pressure sensor, and send data to computer, generate pressure in a computer The logarithmic curve that difference changes over time, while permeability and infiltration coefficient are calculated, and data acquisition time is upstream and downstream pressure Restore balance the 10%~50% of the time, time range is in 20s~1.5h；

Step 9: pore pressure unloading

Third shut-off valve is opened, first passes through displacement pump for the discharge degree in pipeline to 50Pa hereinafter, then by the second pressure regulation Valve discharges the fluid in pipeline, completes the unloading of pore pressure；

Step 10: confining pressure unloading

It first passes through confining pressure pump and the indoor confining pressure of pressure is offloaded to 50Pa hereinafter, then by the first pressure regulator valve that pressure is indoor Fluid release, completes the unloading of confining pressure.

2. a kind of hypotonic rock gas-liquid two according to claim 1 drives pressure pulse decaying permeability test method, feature Be: in step 4, the confining pressure of load is determined by calculation, and calculation formula is as follows:

In formula, P_cFor confining pressure, μ is Poisson's ratio, and D is depth selection, P_graFor barometric gradient.

3. a kind of hypotonic rock gas-liquid two according to claim 1 drives pressure pulse decaying permeability test method, feature Be: in step 8, permeability and infiltration coefficient are calculated by the following formula:

In formula, P_uFor upstream pressure, P_eFor pressure after upstream and downstream balance, Δ P is pulse, V₁For upstream volume, V₂For Downstream pipe volume, t are the die-away time of pulse, and θ is upstream pressure versus time curve slope, and K is infiltration system Number, A are rock sample sectional area, μ_fFor fluid coefficient of viscosity, C_fFor fluid compressibility, L is rock sample length, and k is permeability, and ρ is stream Volume density, g are acceleration of gravity.