CN112161905A - Test device and method for evaluating formation conductivity damage repair - Google Patents
Test device and method for evaluating formation conductivity damage repair Download PDFInfo
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- 238000012360 testing method Methods 0.000 title claims abstract description 96
- 230000008439 repair process Effects 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 20
- 230000015572 biosynthetic process Effects 0.000 title claims abstract description 17
- 239000011435 rock Substances 0.000 claims abstract description 100
- 230000035699 permeability Effects 0.000 claims abstract description 98
- 239000012530 fluid Substances 0.000 claims abstract description 90
- 239000000463 material Substances 0.000 claims abstract description 30
- 239000007789 gas Substances 0.000 claims abstract description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 16
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 8
- 238000010835 comparative analysis Methods 0.000 claims abstract description 5
- 238000005086 pumping Methods 0.000 claims description 40
- 238000006073 displacement reaction Methods 0.000 claims description 37
- 239000007788 liquid Substances 0.000 claims description 26
- 239000002245 particle Substances 0.000 claims description 8
- 239000000919 ceramic Substances 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 6
- 239000003350 kerosene Substances 0.000 claims description 4
- 238000005406 washing Methods 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 claims description 2
- 238000010998 test method Methods 0.000 claims description 2
- 238000011156 evaluation Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 229910001873 dinitrogen Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000011010 flushing procedure Methods 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011981 development test Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- 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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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
Abstract
The invention provides a test device and a method for evaluating formation diversion capability damage repair, which comprises a plunger pump, a first intermediate container, a second intermediate container, a third intermediate container, a rock core holder, a first hand-operated pump, a second hand-operated pump, a first pressure sensor, a second pressure sensor, a third pressure sensor, a nitrogen cylinder, a gas flowmeter, a vacuum pump, a back pressure valve, a measuring cylinder and a beaker. According to the method, the damage degree of permeability of the core can be respectively obtained by introducing the propping agent, the fracturing fluid and the new material into the core, and the repair capability of the new material to the damage of the flow conductivity of the fractured stratum is evaluated through the comparative analysis of the damage degree.
Description
Technical Field
The invention relates to the technical field of petroleum and natural gas development test equipment, in particular to a test device and a method for evaluating formation conductivity damage repair.
Background
The hydraulic fracturing technology is the most extensive measure for increasing the production and injection of oil and gas wells at present, and the principle is that a fracture with high flow conductivity and supported by a fracturing propping agent is generated in an oil and gas layer, so that the seepage resistance of fluid in a stratum near the bottom of the well is reduced, the seepage state of the fluid is changed, and the yield of the oil and gas well or the injection amount of a water injection well is greatly improved. The greater the conductivity of the hydraulic fracture, the greater the amplitude of the well stimulation.
However, when hydraulic fracturing is carried out, various components in the fracturing fluid can cause certain damage to the flow conductivity of the stratum, so that the yield increasing effect of the reservoir is influenced. Therefore, new materials for repairing formation conductivity damage are developed at present. At present, for the effect of repairing the flow conductivity damage of the fractured stratum by the new material, CN201721367745.7 discloses an evaluation device for the damage of the stratum by the external fluid, which can perform damage evaluation test on the external fluid through a constant-pressure liquid injection valve, a liquid mixing container, a liquid guide pipe, a first liquid container, a second liquid container, a liquid return barrel, a pressure detector, a hand-operated pressure control pump, a rock core holder and a switch. However, the device can only inject foreign fluid into the core, and correspondingly observe and measure pressure changes to obtain the evaluation of the damage of the foreign fluid to the stratum, in the test process, the device can only simulate the state of the foreign fluid after entering the core, and can not flush and displace the core as required, can not realize the contrast test after adding various liquids, can not simulate the actual situation after the oil field is exploited to inject new materials into the fractured stratum, and can not play a role in evaluating the damage and repair of the new materials to the stratum conductivity.
Aiming at the defects, a test device for evaluating the damage and the repair of the new material to the flow conductivity of the fractured stratum and a repair capability evaluation method are needed to be invented, and the practical engineering problem is solved.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to evaluate the effect of the new material on repairing the fractured stratum conductivity damage, the invention provides the test device and the method for evaluating the repairing of the stratum conductivity damage, which can effectively test the new material through the test and evaluate the repairing capability of the fractured stratum conductivity damage according to the test data.
The technical scheme adopted by the invention for solving the technical problems is as follows: a test device and method for evaluating damage and repair of formation diversion capability are disclosed, the test device for evaluating damage and repair of formation diversion capability comprises a core holder for holding a core, a nitrogen gas cylinder, a gas flowmeter, a pressure sensor I and a plunger pump, wherein a first pressure sensor is connected to a connecting pipeline at the front end of the core holder, the front end of the core holder is communicated with the rear end of the gas flowmeter through a pipeline, and the front end of the gas flowmeter is connected with the nitrogen gas cylinder through a pipeline; the front end and the rear end of the rock core holder are connected through a pipeline;
the pipeline on the front end of the core holder is connected with a first intermediate container, and displacement fluid is contained in the first intermediate container; a vacuum pump is connected to a connecting pipeline at the front end of the core holder;
the rear end of the rock core holder is respectively connected with a second intermediate container and a third intermediate container, fracturing fluid is contained in the second intermediate container, and repairing fluid is contained in the third intermediate container; the intermediate container I, the intermediate container II and the intermediate container III are respectively connected with a plunger pump pipeline, and the plunger pump is further connected with a beaker through a pipeline;
the back end of the core holder is sequentially connected with a back pressure valve and a measuring cylinder through pipelines; the back pressure valve is respectively connected with a second pressure sensor and a second hand pump through pipelines;
the middle part of the core holder is connected with a third pressure sensor through a pipeline, and the middle part of the core holder is also connected with a first hand pump through a pipeline;
the high-precision plunger pump, the first intermediate container, the second intermediate container, the third intermediate container, the core holder, the first hand pump, the second hand pump, the first pressure sensor, the second pressure sensor, the third pressure sensor, the nitrogen cylinder, the gas flowmeter, the vacuum pump, the measuring cylinder and the beaker are respectively provided with a gate with an independent switch in front and at back of a connecting pipeline and a pipeline branch interface between any two test devices.
The test apparatus described above has the following test methods:
the first step is as follows: firstly, completing the installation of a test device for evaluating the damage and the repair of the formation diversion capability, preparing the same batch of materials such as rock cores, propping agents, fracturing fluids, displacement fluids, repair fluids and the like for the test, measuring data, and carrying out manual seam making on the rock cores;
the second step is that: the method comprises the following steps of (1) loading rock cores into a rock core holder, measuring the gas permeability of each rock core, and determining the particle size of a propping agent selected in a test and the crack width of a corresponding rock core crack according to a Darcy formula and a relational expression between the crack width and the crack permeability;
the third step: respectively filling the displacement fluid, the fracturing fluid and the repairing fluid into a first intermediate container, a second intermediate container and a third intermediate container, filling the test rock core into a rock core holder, applying 5MPa back pressure to a back pressure valve by using a second hand pump, vacuumizing firstly, adjusting a test pipeline after testing perfect air tightness, checking each gate of the test device, opening a plunger pump after confirming that no error exists, setting the plunger pump to be in a constant-current mode, pumping the displacement fluid into the rock core in a forward direction through the first intermediate container, and recording the flow Q after an outlet is stable1And a pressure differential Δ p through the core1Calculating the permeability K of the solution1；
The fourth step: stopping the test device, closing the corresponding gate, then taking out the core in the core holder, laying ceramsite with proper specification on the half core section of the core, then fitting 2 semicylindrical cores into 1 core with cracks, loading the core holder, checking the test device and adjusting the pipeline; at the start of the test, p is first applied to the core holder by means of a hand pump1The confining pressure of the ceramic is controlled to control the width of the gap, and the ceramic particles are fully filled in the gap; then the plunger pump is started and set to be in a constant flow mode, so that the displacement fluid is pumped into the rock core in a positive direction through the middle container I, and the flow Q is recorded after the pressure is stable2And a pressure differential Δ p through the core2Calculating the permeability K in the presence of proppant2；
The fifth step: stopping the plunger pump, unloading the pressure in the pipeline, adjusting the reverse pumping state of the gate, checking the test device, opening the plunger pump again after confirming no error, setting the plunger pump to be in a constant flow mode, pumping the fracturing fluid into the core reversely through the middle container II, and placing about 20-30 min times; adjusting the pipeline to be in a forward pumping state, then opening the plunger pump, setting the pump to be in a constant flow mode, pumping the displacement fluid into the rock core in a forward direction through the middle container for displacement, and recording the flow Q after the pressure is stable3And a pressure differential Δ p through the core3Calculating permeability K of the core in the presence of proppant and fracturing fluid3；
And a sixth step: stopping the plunger pump, relieving the pressure in the pipeline, readjusting the pipeline to be in a reverse pumping state, starting the plunger pump, and pumping the repairing liquid into the rock core in three opposite directions through the intermediate container under the constant flow condition to flush the rock core; stopping the plunger pump, relieving pressure in the pipeline, adjusting the pipeline to a forward pumping state, pumping a displacement fluid into the rock core through an intermediate container in a forward direction in a constant flow mode, displacing the repair fluid, and recording the flow Q after the pressure is stable4And a pressure differential Δ p through the core4And calculating the permeability K of the rock core after the repairing liquid is washed4；
The seventh step: taking out the tested rock core, taking another rock core with the same specification, loading the rock core into a rock core holder of the testing device, adjusting a testing pipeline, and setting the testing pipeline as a forward pumping route; then the plunger pump is started and set to be in a constant flow mode, so that the displacement fluid is pumped into the rock core in a positive direction through the middle container I, and the flow Q is recorded after the pressure is stable5And a pressure differential Δ p through the core5Calculating permeability K of the core5；
Eighth step: stopping the plunger pump and applying p separately on the core holder by hand pump one1The confining pressure is controlled to control the seam width, then the plunger pump is started and set to be in a constant flow mode, so that the displacement fluid is pumped into the rock core in a positive direction through the middle container, and the flow Q is recorded after the pressure is stabilized6And a pressure differential Δ p through the core6Calculating the permeability K of the core without proppant6；
The ninth step: stopping the plunger pump, relieving the pressure in the pipeline, adjusting the gate, and setting the pipeline to be in a reverse pumping state; opening the plunger pump, pumping the repairing liquid into the rock core through the intermediate container in three opposite directions under the condition of constant flow, stopping the plunger pump, relieving the pressure in the pipeline, and then discharging the repairing liquidRegulating the pipeline to be in a forward pumping state, pumping the displacement fluid into the rock core through the middle container in a forward direction in a constant flow mode, displacing the repair fluid, and recording the flow Q after the pressure is stable7And a pressure differential Δ p through the core7And calculating the permeability K of the rock core after the repairing liquid is washed7；
The tenth step: the test selects the cores of the same batch, the properties of the cores are not greatly different, the cores of the two tests are regarded as the same core, and for the core, K6For post-seam permeability, K2For permeability after proppant addition, K3Permeability after addition of fracturing fluid, K4The permeability of the repair liquid after washing is adopted;
the damage degree of the core can be calculated by the following formula:
in the formula, D1The damage degree of the proppant to the permeability;
D2the damage degree of the proppant and the fracturing fluid to the permeability;
D3after a propping agent and a fracturing fluid are added, the damage degree to permeability is flushed by a new material;
D4the seam width is controlled only by confining pressure, and the damage degree to permeability is flushed by a new material;
and evaluating the repairing capability of the new material on the damage of the flow conductivity of the fractured stratum through the comparative analysis of the damage degree.
Further, in the second step, the gas permeability of each core is measured, the particle size of the selected proppant and the width of the corresponding core fracture are determined by the following method:
firstly, taking a rock core, measuring the matrix permeability of the rock core, calculating the crack permeability according to the seam width required by the test to obtain the total permeability during the test, applying confining pressure to the rock core, calculating the permeability of the rock core under different confining pressures, comparing the permeability with a theoretical calculated value, and selecting proper data as the confining pressure value of the test;
wherein, the quantitative relation between the crack width and the crack permeability is as follows:
in the formula, WfIs the slit width, mu m;
Kffor crack permeability, mD or 10-3×μm2；
D is the core diameter, cm.
The fracture permeability and the total core permeability are in a relation formula as follows: kf＝Kt-Km
In the formula, KmAs permeability of the matrix, mD or 10-3×μm2；
KtTo total permeability, mD or 10-3×μm2；
Therefore, the original permeability of the rock core and the total permeability after applying the confining pressure are obtained through tests, the permeability of the cracks of the rock core can be known, and the width of the cracks can be further obtained.
Furthermore, the proppant is a ceramsite proppant, the displacement fluid is kerosene, and the repair fluid is a new material to be detected.
Further, the measurement data is the diameter and the length of the core.
Furthermore, the flow rate of the fracturing fluid pumped to the rock core through the second middle container in the fifth step is 2 PV.
The stratum diversion capability damage repairing test device and method provided by the invention have the beneficial effects that the permeability damage degree of the rock core can be respectively obtained by introducing the propping agent, the fracturing fluid and the new material into the rock core, and the repairing capability of the new material on the fractured stratum diversion capability damage can be evaluated through the comparative analysis of the damage degree.
Drawings
The invention is further illustrated with reference to the following figures and examples.
Fig. 1 is a schematic structural diagram of the preferred embodiment of the present invention.
Figure 2 is a schematic view of the connection of the core holder in front and rear of the preferred embodiment of the invention.
In the figure, 1, a plunger pump 2, a first intermediate container 3, a second intermediate container 4, a third intermediate container 5, a core holder 6, a first pressure sensor 7, a second pressure sensor 8, a third pressure sensor 9, a first hand pump 10, a second hand pump 11, a nitrogen cylinder 12, a gas flowmeter 13, a vacuum pump 14, a back pressure valve 15, a measuring cylinder 16 and a beaker.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.
As shown in fig. 1 and 2, the test device for evaluating formation conductivity damage repair is the best embodiment of the invention, and comprises a core holder 5 for holding a core, a nitrogen cylinder 11, a gas flowmeter 12, a first pressure sensor 6 and a plunger pump 1. In order to ensure the test precision, the plunger pump 1 adopts a high-precision plunger pump 1. A first pressure sensor 6 is connected to a connecting pipeline at the front end of the core holder 5, the front end of the core holder 5 is communicated with the rear end of a gas flowmeter 12 through a pipeline, and the front end of the gas flowmeter 12 is connected with a nitrogen cylinder 11 through a pipeline; the front end and the rear end of the core clamper 5 are connected through a pipeline, and the measuring cylinder 15 is used for recording the flow after the pressure is stable.
The pipeline on the front end of the core holder 5 is connected with a first intermediate container 2, and the first intermediate container 2 is filled with a displacement fluid; and a vacuum pump 13 is also connected to a connecting pipeline at the front end of the core holder 5 (corresponding to the front end of the first pressure sensor 6).
The rear end of the core holder 5 is respectively connected with a second intermediate container 3 and a third intermediate container 4, the second intermediate container 3 is filled with fracturing fluid, and the third intermediate container 4 is filled with repairing fluid; the intermediate container I2, the intermediate container II 3 and the intermediate container III 4 are respectively connected with a plunger pump 1 through pipelines, and the plunger pump 1 is further connected with a beaker 16 through a pipeline.
The back end of the core holder 5 is also sequentially connected with a back pressure valve 14 and a measuring cylinder 15 through another pipeline; the back pressure valve 14 is respectively connected with a second pressure sensor 7 and a second hand pump 10 through pipelines;
the middle part of the core holder 5 is connected with a pressure sensor III 8 through a pipeline, the middle part of the core holder 5 is connected with a hand pump I9 through a pipeline, and particularly, the pipeline between the middle part of the core holder 5 and the pressure sensor III 8 is connected with the hand pump I9 through a pipeline.
In order to conveniently adjust the pressure in the pipeline and the flow direction of various materials such as fracturing fluid, displacement fluid, repairing fluid and the like in the test, a gate which can be independently opened and closed for pressure relief needs to be designed in the pipeline, namely, the gate is provided with an independent switch at the front and the back of a connecting pipeline and a pipeline branch interface between any two test devices in a high-precision plunger pump 1, a first intermediate container 2, a second intermediate container 3, a third intermediate container 4, a core holder, a first hand pump 9, a second hand pump 10, a first pressure sensor 6, a second pressure sensor 7, a third pressure sensor 8, a nitrogen gas bottle 11, a gas flowmeter 12, a vacuum pump 13, a measuring cylinder 15 and a beaker 16. Wherein, the gates of the independent switches are arranged on the pipelines between the vacuum pump 13 and the front end of the core holder 5, the back pressure valve 14, the first intermediate container 2, the second intermediate container 3 and the third intermediate container 4, and the gates of the independent switches are arranged in the front and at the back of the branch interface connected with each pipeline. Specifically, the front end and the rear end of the first intermediate container 2 are respectively provided with a gate with an independent switch, the front end and the rear end of the second intermediate container 3 are respectively provided with a gate with an independent switch, the front end and the rear end of the third intermediate container 4 are respectively provided with a gate with an independent switch, the front end and the rear end of the core clamper 5 are respectively provided with a gate with an independent switch, and the connecting pipelines of the vacuum pump 13 and other devices comprise gates with independent switches on intermediate branches.
The test device provided by the scheme is used for taking the cores in the same batch as test objects, respectively measuring the propping agent, the propping agent and the fracturing fluid, adding the propping agent and the fracturing fluid, flushing by using a new material, controlling the width of a seam by only using confining pressure and then flushing by using the new material through the reasonably arranged test device, obtaining the damage degree under different conditions through measuring and calculating the permeability under different conditions, and finally obtaining the evaluation of the new material used in the test on the damage and repair of the formation flow conductivity.
The specific test process is as follows:
the first step is as follows: firstly, the test device for evaluating the damage and repair of the formation diversion capability is installed, the materials of the rock core, the propping agent, the fracturing fluid, the displacement fluid, the repair fluid and the like in the same batch required by the test are prepared, the diameter, the length and the like of the data rock core are measured, and manual seam making is carried out on the rock core; the proppant is a ceramsite proppant, the displacement fluid is kerosene, and the repair fluid is a new material to be detected.
The second step is that: and (3) loading the rock core into a rock core holder, measuring the gas permeability of each rock core, and determining the particle size of the proppant selected in the test and the width of the corresponding rock core fracture according to the Darcy formula and the relational expression between the fracture width and the fracture permeability.
The gas permeability of each core is measured, the particle size of the selected propping agent and the width of the corresponding core fracture are determined by the following methods:
firstly, taking a rock core, measuring the matrix permeability of the rock core, calculating the crack permeability according to the seam width required by the test to obtain the total permeability during the test, applying confining pressure to the rock core, calculating the permeability of the rock core under different confining pressures, comparing the permeability with a theoretical calculated value, and selecting proper data as the confining pressure value of the test;
wherein, the quantitative relation between the crack width and the crack permeability is as follows:
in the formula, WfIs the slit width, mu m;
Kffor crack permeability, mD or 10-3×μm2；
D is the core diameter, cm.
The fracture permeability and the total core permeability are in a relation formula as follows: kf＝Kt-Km
In the formula, KmAs permeability of the matrix, mD or 10-3×μm2；
KtTo total permeability, mD or 10-3×μm2；
Therefore, the original permeability of the rock core and the total permeability after applying the confining pressure are obtained through tests, so that the permeability of the crack of the rock core can be known, and the width of the crack can be further obtained;
the core permeability is calculated using the darcy formula:
wherein K is the total permeability of the core, D;
q is the flow through the fluid, cm3/s；
μ is the viscosity through the fluid, mPa · s;
l is the core length, cm;
d is the diameter of the core, cm;
a is the cross-sectional area of the core in cm2；
Δ p is the displacement pressure difference across the core, atm.
The third step: respectively filling the displacement fluid, the fracturing fluid and the repairing fluid into a first intermediate container 2, a second intermediate container 3 and a third intermediate container 4, filling the test rock core into a rock core holder, and applying 5MPa back pressure to a back pressure valve 14 by using a second hand pump 10Then, firstly vacuumizing, adjusting a test pipeline after testing perfect air tightness, checking each gate of the test device, opening the plunger pump 1 after confirming no error, setting the mode to be a constant flow mode, pumping the displacement fluid into the rock core in a forward direction through the first intermediate container 2, and recording the flow Q after the outlet is stable1And a pressure differential Δ p through the core1Calculating the permeability K of the solution1。
The fourth step: stopping the test device, closing the corresponding gate, then taking out the core in the core holder, laying ceramsite with proper specification on the half core section of the core, then fitting 2 semicylindrical cores into 1 core with cracks, loading the core holder, checking the test device and adjusting the pipeline; at the beginning of the test, p is first applied to the core holder by means of a hand pump-91The confining pressure of the ceramic is controlled to control the width of the gap, and the ceramic particles are fully filled in the gap; then the plunger pump 1 is started, a constant flow mode is set, the plunger pump is enabled to pump the displacement fluid to the rock core in a positive direction through the middle container I2, and the flow Q is recorded after the pressure is stable2And a pressure differential Δ p through the core2Calculating the permeability K in the presence of proppant2。
The fifth step: stopping the plunger pump 1, relieving the pressure in the pipeline, adjusting the reverse pumping state of the gate, checking the test device, opening the plunger pump 1 again after confirming no error, setting the constant flow mode, reversely pumping a certain amount of fracturing fluid about 2PV to the core through the intermediate container II 3, and standing for about 20-30 min; adjusting the pipeline to be in a forward pumping state, then opening the plunger pump 1, setting the constant flow mode, pumping the displacement fluid into the rock core in a forward direction through the intermediate container I2 for displacement, and recording the flow Q after the pressure is stable3And a pressure differential Δ p through the core3Calculating permeability K of the core in the presence of proppant and fracturing fluid3。
And a sixth step: stopping the plunger pump 1, relieving the pressure in the pipeline, readjusting the pipeline to be in a reverse pumping state, starting the plunger pump 1, and reversely pumping the repairing liquid into the rock core through the intermediate container III 4 under the constant current condition to flush the rock core; then the plunger pump 1 is stopped, the pressure in the pipeline is discharged, the pipeline is adjusted to be in a positive pumping state, and the fluid passes through the middle in a constant flow modePumping a displacement fluid into the rock core in a forward direction by the intermediate container I2, displacing the repair fluid, and recording the flow Q after the pressure is stable4And a pressure differential Δ p through the core4And calculating the permeability K of the rock core after the repairing liquid is washed4。
The seventh step: taking out the tested rock core, taking another rock core with the same specification, loading the rock core into a rock core holder of the testing device, adjusting a testing pipeline, and setting the testing pipeline as a forward pumping route; then the plunger pump 1 is started, a constant flow mode is set, the plunger pump is enabled to pump the displacement fluid to the rock core in a positive direction through the middle container I2, and the flow Q is recorded after the pressure is stable5And a pressure differential Δ p through the core5Calculating permeability K of the core5。
Eighth step: stopping the plunger pump 1 and applying p separately on the core holder by means of the hand pump one 91The confining pressure is controlled to control the seam width, then the plunger pump 1 is started to be set to be in a constant flow mode, the displacement fluid is pumped into the rock core in a positive direction through the middle container I2, and the flow Q is recorded after the pressure is stable6And a pressure differential Δ p through the core6Calculating the permeability K of the core without proppant6。
The ninth step: stopping the plunger pump 1, relieving the pressure in the pipeline, adjusting the gate, and setting the pipeline to be in a reverse pumping state; opening the plunger pump 1, pumping the repairing liquid into the rock core reversely through the third 4 middle container under the condition of constant flow, then stopping the plunger pump 1, relieving the pressure in the pipeline, adjusting the pipeline to be in a forward pumping state again, pumping the displacement liquid into the rock core forwardly through the first 2 middle containers in the constant flow mode, displacing the repairing liquid, and recording the flow Q after the pressure is stable7And a pressure differential Δ p through the core7And calculating the permeability K of the rock core after the repairing liquid is washed7。
The tenth step: the test selects the cores of the same batch, the properties of the cores are not greatly different, the cores of the two tests are regarded as the same core, and for the core, K6For post-seam permeability, K2For permeability after proppant addition, K3Permeability after addition of fracturing fluid, K4The permeability of the repair liquid after washing is shown.
The damage degree of the core can be calculated by the following formula:
in the formula, D1The damage degree of the proppant to the permeability;
D2the damage degree of the proppant and the fracturing fluid to the permeability;
D3after a propping agent and a fracturing fluid are added, the damage degree to permeability is flushed by a new material;
D4the seam width is controlled only by confining pressure, and the damage degree to permeability is flushed by a new material;
and evaluating the repairing capability of the new material on the damage of the flow conductivity of the fractured stratum through the comparative analysis of the damage degree.
In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.
Claims (6)
1. The test device for evaluating the stratum conductivity damage repair comprises a core clamper (5) for clamping a core, and is characterized in that: the device is characterized by further comprising a nitrogen cylinder (11), a gas flowmeter (12), a first pressure sensor (6) and a plunger pump (1), wherein the first pressure sensor (6) is connected to a connecting pipeline at the front end of the core holder (5), the front end of the core holder (5) is communicated with the rear end of the gas flowmeter (12) through a pipeline, and the front end of the gas flowmeter (12) is connected with the nitrogen cylinder (11) through a pipeline; the front end and the rear end of the core holder (5) are connected through a pipeline;
the pipeline on the front end of the core holder (5) is connected with a first intermediate container (2), and the first intermediate container (2) is filled with a displacement fluid; a vacuum pump (13) is connected to a connecting pipeline at the front end of the core clamper (5);
the rear end of the core holder (5) is respectively connected with a second intermediate container (3) and a third intermediate container (4), the second intermediate container (3) is filled with fracturing fluid, and the third intermediate container (4) is filled with repairing fluid; the intermediate container I (2), the intermediate container II (3) and the intermediate container III (4) are respectively connected with a plunger pump (1) through pipelines, and the plunger pump (1) is also connected with a beaker (16) through a pipeline;
the back end of the core holder (5) is sequentially connected with a back pressure valve (14) and a measuring cylinder (15) through pipelines; the back pressure valve (14) is respectively connected with a second pressure sensor (7) and a second hand pump (10) through pipelines;
the middle part of the core holder (5) is connected with a third pressure sensor (8) through a pipeline, and the middle part of the core holder (5) is also connected with a first hand pump (9) through a pipeline;
the high-precision plunger pump comprises a high-precision plunger pump body (1), a middle container body (2), a middle container body (3), a middle container body (4), a core holder, a hand pump body (9), a hand pump body (10), a pressure sensor body (6), a pressure sensor body (7), a pressure sensor body (8), a nitrogen cylinder (11), a gas flowmeter (12), a vacuum pump (13), a measuring cylinder (15) and a beaker (16), wherein connecting pipelines and pipeline branch interfaces between any two test devices are respectively provided with a gate with an independent switch in the front and at the back.
2. The test device and the method for evaluating the formation conductivity damage repair according to claim 1, wherein: the following test methods were used:
the first step is as follows: firstly, completing the installation of a test device for evaluating the damage and the repair of the formation diversion capability, preparing the same batch of materials such as rock cores, propping agents, fracturing fluids, displacement fluids, repair fluids and the like for the test, measuring data, and carrying out manual seam making on the rock cores;
the second step is that: the method comprises the following steps of (1) loading rock cores into a rock core holder, measuring the gas permeability of each rock core, and determining the particle size of a propping agent selected in a test and the crack width of a corresponding rock core crack according to a Darcy formula and a relational expression between the crack width and the crack permeability;
the third step: respectively filling a displacement fluid, a fracturing fluid and a repairing fluid into a first intermediate container (2), a second intermediate container (3) and a third intermediate container (4), filling a test rock core into a rock core holder, applying 5MPa back pressure to a back pressure valve (14) by using a second hand-operated pump (10), vacuumizing firstly, adjusting a test pipeline after the test airtightness is intact, checking each gate of the test device, opening a plunger pump (1) after the test is confirmed to be correct, setting the test pipeline into a constant-current mode, pumping kerosene into the rock core in a forward direction through the first intermediate container (2), and recording a flow Q after an outlet is stable1And a pressure differential Δ p through the core1Calculating the permeability K of the solution1；
The fourth step: stopping the test device, closing the corresponding gate, then taking out the core in the core holder, laying ceramsite with proper specification on the half core section of the core, then fitting 2 semicylindrical cores into 1 core with cracks, loading the core holder, checking the test device and adjusting the pipeline; at the beginning of the test, p is first applied to the core holder by means of a hand pump I (9)1The confining pressure of the ceramic is controlled to control the width of the gap, and the ceramic particles are fully filled in the gap; then the plunger pump (1) is started and set to be in a constant flow mode, the displacement fluid is pumped into the rock core in a positive direction through the intermediate container I (2), and the flow Q is recorded after the pressure is stable2And a pressure differential Δ p through the core2Calculating the permeability K in the presence of proppant2；
The fifth step: stopping the plunger pump (1), relieving the pressure in the pipeline, and adjusting the pump shape of the gate in the reverse directionChecking the test device, opening the plunger pump (1) again after the test device is confirmed to be correct, setting the constant flow mode, reversely pumping the fracturing fluid into the rock core through the intermediate container II (3), and standing for about 20-30 min; adjusting the pipeline to be in a forward pumping state, then opening the plunger pump (1), setting the pump to be in a constant flow mode, pumping the displacement fluid into the rock core in a forward direction through the intermediate container I (2) for displacement, and recording the flow Q after the pressure is stable3And a pressure differential Δ p through the core3Calculating permeability K of the core in the presence of proppant and fracturing fluid3；
And a sixth step: stopping the plunger pump (1), relieving the pressure in the pipeline, readjusting the pipeline to be in a reverse pumping state, starting the plunger pump (1), and reversely pumping the repairing liquid into the rock core through the intermediate container III (4) under the constant current condition to flush the rock core; then stopping the plunger pump (1), relieving the pressure in the pipeline, adjusting the pipeline to be in a forward pumping state, pumping the displacement fluid into the rock core in a forward direction through the intermediate container I (2) in a constant flow mode, displacing the repair fluid, and recording the flow Q after the pressure is stable4And a pressure differential Δ p through the core4And calculating the permeability K of the rock core after the repairing liquid is washed4；
The seventh step: taking out the tested rock core, taking another rock core with the same specification, loading the rock core into a rock core holder (5) of the testing device, adjusting a testing pipeline, and setting the testing pipeline as a forward pumping route; then the plunger pump (1) is started and set to be in a constant flow mode, the displacement fluid is pumped into the rock core in a positive direction through the intermediate container I (2), and the flow Q is recorded after the pressure is stable5And a pressure differential Δ p through the core5Calculating permeability K of the core5；
Eighth step: stopping the plunger pump (1) and applying p on the core holder by shaking the pump one (9) respectively1The confining pressure is controlled to control the seam width, then the plunger pump (1) is started to be set to be in a constant flow mode, the displacement fluid is pumped into the rock core in a forward direction through the middle container I (2), and the flow Q is recorded after the pressure is stable6And a pressure differential Δ p through the core6Calculating the permeability K of the core without proppant6；
The ninth step: stopping the plunger pump (1) and removing the plunger pump from the pipelineThe gate is adjusted, and the pipeline is set to be in a reverse pumping state; opening the plunger pump (1), reversely pumping the repairing liquid into the rock core through the middle container III (4) under the constant current condition, then stopping the plunger pump (1), unloading the pressure in the pipeline, adjusting the pipeline to be in a forward pumping state again, pumping the displacement liquid into the rock core through the middle container I (2) in a forward direction under the constant current mode, displacing the repairing liquid, and recording the flow Q after the pressure is stable7And a pressure differential Δ p through the core7And calculating the permeability K of the rock core after the repairing liquid is washed7；
The tenth step: the test selects the cores of the same batch, the properties of the cores are not greatly different, the cores of the two tests are regarded as the same core, and for the core, K6For post-seam permeability, K2For permeability after proppant addition, K3Permeability after addition of fracturing fluid, K4The permeability of the repair liquid after washing is adopted;
the damage degree of the core can be calculated by the following formula:
in the formula, D1The damage degree of the proppant to the permeability;
D2the damage degree of the proppant and the fracturing fluid to the permeability;
D3after a propping agent and a fracturing fluid are added, the damage degree to permeability is flushed by a new material;
D4the seam width is controlled only by confining pressure, and the damage degree to permeability is flushed by a new material;
and evaluating the repairing capability of the new material on the damage of the flow conductivity of the fractured stratum through the comparative analysis of the damage degree.
3. The test device and the method for evaluating the formation conductivity damage repair according to claim 2, wherein: in the second step, the gas permeability of each core is measured, the grain size of the selected propping agent and the width of the corresponding core fracture are determined by the following methods:
firstly, taking a rock core, measuring the matrix permeability of the rock core, calculating the crack permeability according to the seam width required by the test to obtain the total permeability during the test, applying confining pressure to the rock core, calculating the permeability of the rock core under different confining pressures, comparing the permeability with a theoretical calculated value, and selecting proper data as the confining pressure value of the test;
wherein, the quantitative relation between the crack width and the crack permeability is as follows:
in the formula, WfIs the slit width, mu m;
Kffor crack permeability, mD or 10-3×μm2；
D is the core diameter, cm.
The fracture permeability and the total core permeability are in a relation formula as follows: kf＝Kt-Km
In the formula, KmAs permeability of the matrix, mD or 10-3×μm2；
KtTo total permeability, mD or 10-3×μm2；
Therefore, the original permeability of the rock core and the total permeability after applying the confining pressure are obtained through tests, the permeability of the cracks of the rock core can be known, and the width of the cracks can be further obtained.
4. The test device and the method for evaluating the formation conductivity damage repair according to claim 2, wherein: the proppant is a ceramsite proppant, the displacement fluid is kerosene, and the repair fluid is a new material to be detected.
5. The test device and the method for evaluating the formation conductivity damage repair according to claim 2, wherein: the measurement data is the diameter and the length of the rock core.
6. The test device and the method for evaluating the formation conductivity damage repair according to claim 2, wherein: in the fifth step, the flow rate of the fracturing fluid pumped to the core in the reverse direction through the intermediate container II (3) is 2 PV.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113389535A (en) * | 2021-07-27 | 2021-09-14 | 东北大学 | Experimental device and method for simulating proppant laying and permeability evolution |
| CN114136800A (en) * | 2021-12-01 | 2022-03-04 | 中南大学 | Multi-field coupling low-permeability rock sample hydraulic fracture evolution multi-scale synchronous monitoring device |
-
2020
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113389535A (en) * | 2021-07-27 | 2021-09-14 | 东北大学 | Experimental device and method for simulating proppant laying and permeability evolution |
| CN113389535B (en) * | 2021-07-27 | 2022-06-10 | 东北大学 | Experimental method for simulating proppant laying and permeability evolution |
| CN114136800A (en) * | 2021-12-01 | 2022-03-04 | 中南大学 | Multi-field coupling low-permeability rock sample hydraulic fracture evolution multi-scale synchronous monitoring device |
| CN114136800B (en) * | 2021-12-01 | 2024-04-26 | 中南大学 | Multi-field coupling hypotonic rock sample hydraulic fracture evolution multi-scale synchronous monitoring device |
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