CN113027418B - Oil field water injection well pollution blockage removal experiment testing device and testing effect evaluation method - Google Patents
Oil field water injection well pollution blockage removal experiment testing device and testing effect evaluation method Download PDFInfo
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Abstract
The invention discloses a testing device for pollution blockage removal experiments of an oil field water injection well and a testing effect evaluation method, wherein the evaluation method comprises the following steps: step 2: simulating a pollution process of the core of the water injection well according to the pollution reason of the water injection well; and step 3: simulating an acidification and blockage removal process of a water injection well by displacing acid liquor for the rock core; and 4, step 4: calculating the contamination coefficient X from the permeability1And acidifying deblocking coefficient X2According to X1And X2Evaluating the pollution blockage removing effect of the water injection well; the method truly simulates the pollution and acidification blockage removal process of the injection well through an experimental method, and evaluates the pollution degree and acidification blockage removal effect of the injection well based on the permeability ratio, thereby quantitatively evaluating the pollution degree and acidification blockage removal effect of the injection well.
Description
Technical Field
The invention relates to the technical field of petroleum engineering, in particular to a testing device and a testing effect evaluation method for an oil field water injection well pollution blockage removal experiment.
Background
The oilfield water injection is to inject clean water or sewage meeting certain water quality standards into an oil layer through a water injection well so as to supplement formation energy and maintain certain oil layer pressure. The water injection of oil field is an important technical measure for making the oil well produce high and stable yield for a long time, and is also an oil extraction method for improving the crude oil recovery rate of the oil field. At present, most low-permeability oil reservoirs in China face high water injection pressure, difficulty in stratum liquid absorption and low water injection quantity, and further the water injection development effect of oil fields is influenced. The reason is that the formation physical property is poor, and in the drilling process, the drilling fluid is incompatible with the formation, so that the drilling fluid reacts with certain substances in the formation or solid-phase particles in the drilling fluid block the formation, and the initial water injection pressure of a water injection well is high; on the other hand, the stratum has better physical properties, in the water injection process, the injected water is incompatible with the stratum, so that the injected water reacts with certain substances in the stratum or solid-phase particles in the injected water block the stratum, the water injection well has lower initial water injection and the water injection pressure is gradually increased along with the progress of the water injection process.
The acidification plug removal technology is one of the commonly used technologies for reservoir reconstruction, and is used for improving the connectivity of internal pore channels of rocks, removing stratum pollution, and improving the production capacity of oil and gas wells or the injection capacity of water injection wells by corroding plugs in rock pores or certain mineral components of bedrocks by using acid solution. However, after some oil field water injection wells are acidized, the water injection pressure of the water injection wells cannot be reduced, or the water injection pressure is reduced and then rises rapidly. Therefore, the acidizing and plugging removal effect of the water injection well needs to be evaluated by an indoor experiment method, and the next water injection development of the oil field water injection well is guided according to the evaluation result. In the existing evaluation aiming at the acidizing and plugging removal effects of the water injection well, the corrosion capacity of the acid solution on rock mineral components or impurities of injected water is evaluated from the angle of the reaction of the acid solution and a solid phase, and the cause of pollution of the injection well is not judged; and the method does not start from the perspective of liquid displacement, and can not truly simulate the pollution of an injection well and the acidification blockage removal process.
Disclosure of Invention
The invention provides a device for testing pollution blockage removal experiments of an oil field water injection well and a method for evaluating testing effect, which aim at the problems in the prior art and truly simulate the pollution of the injection well and the acidification blockage removal process.
The technical scheme adopted by the invention is as follows:
a pollution blockage removal experiment testing device for an oil field water injection well comprises a constant-speed constant-pressure pump, an intermediate container, a rock core holder and a waste liquid pool which are connected in sequence through pipelines; the core holder is also connected with a confining pressure pump for applying pressure to a core arranged in the core holder; and a pressure gauge is arranged on a pipeline between the middle container and the core holder.
A test effect evaluation method of an oil field water injection well pollution blockage removal experiment test device comprises the following steps:
step 1: judging the pollution reason of the water injection well according to the water injection pressure change of the water injection well;
step 2: simulating a pollution process of the core of the water injection well according to the pollution reason of the water injection well;
and step 3: simulating an acidification and blockage removal process of a water injection well by displacing acid liquor for the rock core;
and 4, step 4: calculating the contamination coefficient X from the permeability1And acidifying deblocking coefficient X2According to X1And X2And evaluating the pollution blockage removing effect of the water injection well.
Further, the process for judging the cause of the pollution of the water injection well in the step 1 is as follows:
if the average water injection pressure P in the first month after the water injection well begins to inject water1> half the original pressure of the formation PiAnd/2, the drilling fluid is polluted;
if the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratum i2, and the average water injection pressure P in one month at present2> half the original pressure of the formation PiAnd/2, water injection pollution is caused;
if the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratum i2, and the average water injection pressure P in one month at present2Less than or equal to half of original pressure P of stratumiAnd 2, no pollution is caused.
Further, the calculation process of the pollution coefficient in the step 4 is as follows:
s11: determination of initial permeability K of core0；
S12: simulating core pollution;
s13: determination of permeability K after core contamination1；
S14: calculating the contamination coefficient X1：
Further, the calculation process of the acidification and blockage removal coefficient in the step 4 is as follows:
s21: determination of initial permeability K of core0；
S22: simulating core acidizing and unblocking;
s23: measuring permeability K of rock core after acidizing and plugging removal2；
S24: calculating acidification blockage removal coefficient X2：
Further, the initial permeability K of the core0The measurement calculation method is as follows:
pouring standard saline water into an intermediate container, loading the core into a core holder, and loading confining pressure on the core by using a confining pressure pump; adjusting the constant-speed constant-pressure pump to a constant flow Q; after the pressure value of the pressure gauge is stabilized, the pressure is displayed as P3Closing the constant-speed constant-pressure pump, and discharging confining pressure;
initial permeability K0Comprises the following steps:
wherein, mu0Is the standard brine viscosity, D is the core diameter, P0Is at standard atmospheric pressure.
Further, the injection time t of the polluted liquid in the core pollution simulation process in the step 21The calculation process is as follows:
s31: calculating the core porosity Vp：
Where ρ iswIs standard brine density, m1Is core mass, m2Saturated standard brine core mass;
s32: pouring the polluted liquid into an intermediate container, loading the core with the initial permeability into a core holder, and loading confining pressure on the core by using a confining pressure pump; the constant-speed constant-pressure pump is adjusted to a constant flow Q, and the injection time is t1Closing the constant-speed constant-pressure pump and dischargingThe confining pressure is removed, and the simulation of the core pollution process is completed;
wherein, C1Is the volume multiple of the polluted liquid;
the calculation process of the acid liquor injection time t2 in the process of simulating the acidizing and plugging removal of the water injection well in the step 3 is as follows:
pouring acid liquor into an intermediate container, and loading the polluted rock core into a rock core holder; loading confining pressure on the rock core by using a confining pressure pump, adjusting the constant-speed constant-pressure pump to be at a constant flow Q, and setting the injection time to be t2When the constant-speed constant-pressure pump is started, the constant-speed constant-pressure pump is closed, and the confining pressure is released;
wherein, C2Is the volume multiple of the acid liquor.
Further, the core contamination permeability K1The calculation method is as follows:
pouring standard saline water into an intermediate container, and loading the polluted rock core into a rock core holder; loading confining pressure on the rock core by using a confining pressure pump, and adjusting the constant-speed constant-pressure pump to a constant flow Q; after the pressure value of the pressure gauge is stabilized, the pressure is displayed as P4Closing the constant-speed constant-pressure pump, and discharging confining pressure; then K is1Comprises the following steps:
wherein: l is the length of the core, D is the diameter of the core, P4Is a constant speed constant pressure pump pressure value, P0Is at standard atmospheric pressure.
Further, the permeability K of the acidized and unplugged rock core2The calculation method is as follows:
pouring standard saline water into an intermediate container, loading the acidized and unplugged rock core into a rock core holder, and feeding the rock core holder by using a confining pressure pumpLoading confining pressure on a rock core, and adjusting a constant-speed constant-pressure pump to a constant flow Q; after the pressure value of the constant-speed constant-pressure pump is stabilized, the pressure of the pressure gauge is displayed as P5Closing the constant-speed constant-pressure pump, and discharging confining pressure; then K is2Comprises the following steps:
wherein: l is the length of the core, D is the diameter of the core, P5Is a constant speed constant pressure pump pressure value, P0Is at standard atmospheric pressure.
Further, the evaluation criteria of the pollution blockage removing effect of the water injection well are as follows:
if X1No more than 0.2, the pollution is I-level pollution; if 0.2 < X1Less than or equal to 0.5, the pollution is level II; if X is more than 0.51If the content is less than or equal to 0.7, the pollution is level III pollution; if X1If the pollution is more than 0.7, the pollution is IV-level pollution;
if X2When the plugging rate is more than 0.7, I-level plugging removal is performed; if X is more than 0.52When the plugging rate is less than or equal to 0.7, the plugging is removed in grade II; if 0.2 < X2When the plugging rate is less than or equal to 0.5, the third-level plugging removal is performed; if X2And (4) less than or equal to 0.2, performing IV-grade unblocking.
The invention has the beneficial effects that:
(1) the method comprises the steps of firstly judging the pollution reason of the water injection well, then simulating the pollution of the core of the water injection well according to the pollution type of the water injection well, and simulating the acidification and blockage removal process by replacing acid liquor for the core; truly simulating the pollution of an injection well and the acidification blockage removal process;
(2) the method evaluates the pollution degree and the acidification and blockage removal effects of the water injection well based on the permeability ratio, and quantitatively evaluates the pollution degree and the acidification and blockage removal effects of the water injection well.
Drawings
FIG. 1 is a schematic structural diagram of a water injection well pollution blockage removal experiment testing device.
In the figure: 1-constant-speed constant-pressure pump, 2-connecting pipeline, 3-intermediate container, 4-pressure gauge, 5-confining pressure pump, 6-core holder, 7-core, and 8-waste liquid pool.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
As shown in fig. 1, the test device for pollution blockage removal experiment of the oilfield water injection well comprises a constant-speed constant-pressure pump, an intermediate container, a core holder and a waste liquid pool which are sequentially connected through a pipeline; the core holder is also connected with a confining pressure pump for applying pressure to a core arranged in the core holder; and a pressure gauge is arranged on a pipeline between the middle container and the core holder.
A test effect evaluation method of an oil field water injection well pollution blockage removal experiment test device comprises the following steps:
firstly, calculating the pore volume V of the rock corep：
Making an underground rock sample of an oil field water injection well into a standard rock core (the diameter is D, the length is L), putting the rock core into a constant-temperature drying box, setting the temperature to be the formation temperature T of the water injection well, drying for 12 hours, taking out the rock core, and measuring the mass m of the rock core by using a balance1。
The cores were placed in standard saline (2.0% KCl + 5.5% NaCl + 0.45% MgCl)2+0.55％CaCl2) Vacuumizing to saturate standard saline water until no gas is blown out, taking out the rock sample, draining the liquid on the surface of the rock sample after 10 minutes, and measuring the mass m of the rock sample of the saturated standard saline water by using a balance2And then putting the core into a constant-temperature drying oven for continuous drying.
Calculating the core porosity Vp：
Where ρ iswIs standard brine density, m1Is core mass, m2Saturated standard brine core mass;
step 1: judging the pollution reason of the water injection well according to the water injection pressure change of the water injection well;
if the average water injection pressure P in the first month after the water injection well begins to inject water1> half the original pressure of the formation PiAnd/2, then the stratum is consideredThe property is poor, the drilling fluid has great damage to stratum blockage in the drilling process, and the drilling fluid pollution is judged.
If the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratum i2, and the average water injection pressure P in one month at present2> half the original pressure of the formation PiAnd/2, the physical property of the stratum is considered to be good, the injected water has great damage to the blockage of the stratum in the water injection process, and the injected water is judged to be polluted.
If the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratum i2, and the average water injection pressure P in one month at present2Less than or equal to half of original pressure P of stratumiAnd 2, no pollution is caused.
Step 2: simulating a pollution process of the core of the water injection well according to the pollution reason of the water injection well;
firstly, calculating the initial permeability K of the rock core0：
Pouring standard saline water into the middle container 3, loading the rock core 7 into the rock core holder 6, and loading confining pressure on the rock core by using the confining pressure pump 5; the constant-speed constant-pressure pump 1 is adjusted to a constant flow rate Q (cm)3S); after the 4 pressure value of the pressure gauge is stabilized, the pressure is displayed as P3(10-1MPa), the constant-speed constant-pressure pump 1 is closed, and the confining pressure is released;
initial permeability K0(μm2) Comprises the following steps:
wherein, mu0Is the viscosity of standard brine (mPas), D is the core diameter (cm), P0Is at standard atmospheric pressure (10)-1MPa)。
Pouring polluted liquid (drilling fluid or injected water) into the intermediate container 3, loading the core with the initial permeability measured into a core holder 6, and loading confining pressure on the core by using a confining pressure pump 5; the constant-speed constant-pressure pump 1 is adjusted to a constant flow Q, and the injection time is t1Closing the constant-speed constant-pressure pump 1 and discharging confining pressure;
wherein, C1Is the volume multiple of the polluted liquid.
And then determining the permeability of the polluted rock core:
pouring standard saline water into the middle container 3, loading the polluted rock core into the rock core holder 6, loading confining pressure on the rock core by using the confining pressure pump 5, and adjusting the constant-speed constant-pressure pump 1 to a constant flow Q; after the 4 pressure value of the pressure gauge is stabilized, the pressure is displayed as P4And closing the constant-speed constant-pressure pump 1 to discharge confining pressure. Calculating permeability K after core pollution1(μm2)：
Wherein: l is the length of the core, D is the diameter of the core, P4Is a constant-speed constant-pressure pump pressure value (10)-1MPa)，P0Is at standard atmospheric pressure (10)-1MPa)。
And step 3: simulating an acidification and blockage removal process of a water injection well by displacing acid liquor for the rock core;
pouring acid liquor into the intermediate container 3, loading the polluted rock core into the rock core holder 6, and loading confining pressure on the rock core by using the confining pressure pump 5; the constant-speed constant-pressure pump 1 is adjusted to a constant flow Q, and the injection time is t2And the confining pressure is released to finish the acidification process.
Wherein, C2Is the volume multiple of the acid liquor.
Measuring permeability K of rock core after acidizing and deblocking2(μm2)
Pouring standard saline water into the intermediate container 3, loading the acidized and unplugged rock core into a rock core holder 6, loading confining pressure on the rock core by using a confining pressure pump 5,the constant-speed constant-pressure pump 1 is adjusted to a constant flow Q, and after the pressure value of the constant-speed constant-pressure pump 1 is stabilized, the pressure of the pressure gauge 4 is displayed as P5And closing the constant-speed constant-pressure pump 1 to discharge confining pressure. Calculating the permeability K of the acidized and unplugged rock core2：
Wherein: l is the length of the core, D is the diameter of the core, P5Is a constant-speed constant-pressure pump pressure value (10)-1MPa)，P0Is at standard atmospheric pressure (10)-1MPa)。
And 4, step 4: calculating the contamination coefficient X from the permeability1And acidifying deblocking coefficient X2According to X1And X2And evaluating the pollution blockage removing effect of the water injection well.
Contamination coefficient X1：
Acidizing unblocking coefficient X2：
The evaluation standard of the pollution blockage removing effect of the water injection well is as follows:
if X1No more than 0.2, the pollution is I-level pollution; if 0.2 < X1Less than or equal to 0.5, the pollution is level II; if X is more than 0.51If the content is less than or equal to 0.7, the pollution is level III pollution; if X1If the pollution is more than 0.7, the pollution is IV-level pollution;
if X2When the plugging rate is more than 0.7, I-level plugging removal is performed; if X is more than 0.52When the plugging rate is less than or equal to 0.7, the plugging is removed in grade II; if 0.2 < X2When the plugging rate is less than or equal to 0.5, the third-level plugging removal is performed; if X2And (4) less than or equal to 0.2, performing IV-grade unblocking.
Examples
A test effect evaluation method of an oil field water injection well pollution blockage removal experiment test device comprises the following steps:
firstly, calculating the pore volume V of the rock corep：
The method comprises the steps of manufacturing an underground rock sample of the water injection well of the oil field into a standard rock core (the diameter is 2.54cm, the length is 5cm), putting the rock core into a constant-temperature drying box, setting the temperature to be 80 ℃ of the formation temperature of the water injection well, drying for 12 hours, taking out the rock core, and measuring the mass of the rock core by using a balance to be 0.054 kg.
The cores were placed in standard saline (2.0% KCl + 5.5% NaCl + 0.45% MgCl)2+0.55％CaCl2) And vacuumizing the saturated standard saline water until no gas is blown out of the liquid level, taking out the rock sample, measuring the mass of the rock sample with the saturated standard saline water to be 0.058kg by using a balance after the liquid on the surface of the rock sample is drained, and then putting the rock core into a constant-temperature drying oven for continuous drying.
Calculating the core porosity V using the following formulap：
The pore volume of the rock core is calculated to be 4.0cm3。
Step 1: judging the pollution reason of the water injection well according to the water injection pressure change of the water injection well;
collecting injection pressure data of a water injection well, wherein the original formation pressure is 28MPa, and the average water injection pressure of the water injection well in the first month after water injection is started is 7.1MPa and is not higher than half of the original formation pressure; at present, the average water injection pressure within one month is 18.9MPa and is higher than half of the original pressure of the stratum, the physical property of the stratum is considered to be better, but in the water injection process, injected water has great damage to the stratum blockage, and the water injection well is judged to be polluted by the injected water.
Step 2: simulating a pollution process of the core of the water injection well according to the pollution reason of the water injection well;
firstly, calculating the initial permeability K of the rock core0：
Pouring standard saline water into the middle container 3, loading the dried rock core into the rock core holder 6, loading confining pressure 5MPa to the rock core by using the confining pressure pump 5, and loading the constant-speed constant-pressure pump1 adjusted to a constant flow of 0.033cm3And/s, after the pressure value of the pressure gauge 4 is stabilized, the pressure is displayed to be 0.58 MPa. And closing the constant-speed constant-pressure pump 1 and discharging confining pressure. The viscosity of the standard brine is 1mPa · s, and the initial permeability of the core is calculated by adopting the following formula
To obtain K0Is 6.8 multiplied by 10-3μm2。
Simulating core pollution, pouring the injected water into the intermediate container 3, and loading the core with the initial permeability into the core holder 6. The confining pressure 5MPa is loaded on the rock core by using the confining pressure pump 5, and the constant-speed constant-pressure pump 1 is adjusted to a constant flow of 0.033cm3Injection of 20 pore volumes of injection water, i.e. C1And (5) calculating to obtain the injection time of 40min, closing the constant-speed constant-pressure pump 1, and releasing confining pressure to finish the pollution simulation process, wherein the injection time is 20 min.
Measuring permeability of polluted rock core, pouring standard saline water into the intermediate container 3, loading the polluted rock core into the rock core holder 6, loading confining pressure 5MPa to the rock core by using the confining pressure pump 5, and adjusting the constant-speed constant-pressure pump 1 to a constant flow of 0.033cm3S; and after the pressure value of the pressure gauge 4 is stabilized, the pressure is displayed to be 1.21MPa, the constant-speed constant-pressure pump 1 is closed, and the confining pressure is released. Calculating the permeability of the polluted rock core by adopting the following formula:
the calculated permeability after contamination was 2.92X 10-3μm2。
And step 3: simulating an acidification and blockage removal process of a water injection well by displacing acid liquor for the rock core;
pouring acid liquor into an intermediate container 3, loading the polluted rock core into a rock core holder 6, loading confining pressure 5MPa to the rock core by using a confining pressure pump 5, and adjusting a constant-speed constant-pressure pump 1 to a constant flow of 0.033cm3Per s, injecting an acid solution of 10 times the void volume, i.e. C2And (5) when the injection time is 10 min, closing the constant-speed constant-pressure pump and discharging the confining pressure. Calculating the acid liquor injection time by adopting the following formula:
measuring permeability K of rock core after acidizing and plugging removal2
Pouring standard saline water into the intermediate container 3, loading the acidized and unplugged rock core into the rock core holder 6, loading confining pressure 5MPa to the rock core by using the confining pressure pump 5, adjusting the constant-speed constant-pressure pump 1 to be at a constant flow Q, and displaying the pressure value of the pressure gauge 4 to be 0.66MPa after the pressure value of the constant-speed constant-pressure pump 1 is stabilized. And closing the constant-speed constant-pressure pump 1 and discharging confining pressure. Calculating the permeability K of the acidized and unplugged rock core by adopting the following formula2：
Calculating to obtain K2＝5.78×10-3μm2。
And 4, step 4: calculating the contamination coefficient X from the permeability1And acidifying deblocking coefficient X2According to X1And X2And evaluating the pollution blockage removing effect of the water injection well.
Calculating to obtain X1＝0.43，X2＝0.85。
Judging that the water injection well is injected water with II-level pollution and I-level acidification blockage removal effect.
The method comprises the steps of firstly classifying the pollution reasons of the water injection well according to the change condition of the water injection pressure of the water injection well of the oil field; simulating a pollution process of the water injection well core according to the pollution type of the water injection well; then, simulating an acidification and blockage removal process by displacing acid liquor for the rock core; and finally, evaluating the pollution degree of the water injection well and the acidizing and plugging removal effects based on the permeability ratio. Carrying out experimental simulation on the pollution process and the acidification blockage removing process of the oil field water injection well by using an experimental method, and evaluating the pollution blockage removing effect of the oil field water injection well; the method can simulate the pollution of the injection well and the acidification blockage removing process more truly, and quantitatively evaluate the pollution degree of the injection well and the acidification blockage removing effect. The method provides reference for the next step of water injection development of the oil field, and has reliable principle, strong operability and wide application prospect.
Claims (4)
1. A test effect evaluation method of a pollution blockage removal experiment test device for an oil field water injection well is characterized in that,
the testing device comprises a constant-speed constant-pressure pump (1), an intermediate container (3), a core holder (6) and a waste liquid pool (8) which are sequentially connected through a pipeline (2); the core holder (6) is also connected with a confining pressure pump (5) for applying pressure to a core (7) arranged in the core holder (6); a pressure gauge (4) is arranged on a pipeline between the middle container (3) and the core holder (6);
the test effect evaluation method comprises the following steps:
step 1: judging the pollution reason of the water injection well according to the water injection pressure change of the water injection well; the process for judging the pollution reason of the water injection well comprises the following steps:
if the average water injection pressure P in the first month after the water injection well begins to inject water1> half the original pressure of the formation PiAnd/2, the drilling fluid is polluted;
if the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratumi2, and the average water injection pressure P in one month at present2> half the original pressure of the formation Pi(iii) water flooding contamination;
if the average water injection pressure P in the first month after the water injection well begins to inject water1Less than or equal to half of original pressure P of stratumi2, and the average water injection pressure P in one month at present2Less than or equal to half of original pressure P of stratumi2, no pollution is caused;
step 2: simulating a pollution process of the core of the water injection well according to the pollution reason of the water injection well;
contaminated liquid injection time t in core contamination simulation process1The calculation process is as follows: wherein the contaminated fluid comprises drilling fluid or injected water;
s31: calculating the core porosity Vp：
Where ρ iswIs standard brine density, m1Is core mass, m2Saturated standard brine core mass;
s32: pouring the polluted liquid into an intermediate container (3), loading the core with the initial permeability measured into a core holder (6), and loading confining pressure on the core by using a confining pressure pump (5); the constant-speed constant-pressure pump (1) is adjusted to a constant flow Q, and the injection time is t1Closing the constant-speed constant-pressure pump, and releasing confining pressure to complete the simulation of the core pollution process;
wherein, C1Is the volume multiple of the polluted liquid;
and step 3: simulating an acidification and blockage removal process of a water injection well by displacing acid liquor for the rock core;
the calculation process of the acid liquor injection time t2 in the acidification and blockage removal process of the simulated water injection well is as follows:
pouring acid liquor into the intermediate container (3), and loading the polluted rock core into a rock core holder (6); loading confining pressure on the rock core by using a confining pressure pump (5), adjusting the constant-speed constant-pressure pump (1) to be at a constant flow Q, and injecting for t2When the constant-speed constant-pressure pump (1) is closed, the confining pressure is discharged;
wherein, C2Is the volume multiple of the acid liquor;
and 4, step 4: calculating the contamination coefficient X from the permeability1And acidifying deblocking coefficient X2According to X1And X2Evaluating the pollution blockage removing effect of the water injection well; the evaluation method is as follows:
if X1No more than 0.2, the pollution is I-level pollution; if 0.2 < X1Less than or equal to 0.5, the pollution is level II; if X is more than 0.51If the content is less than or equal to 0.7, the pollution is level III pollution; if X1If the pollution is more than 0.7, the pollution is IV-level pollution;
if X2When the plugging rate is more than 0.7, I-level plugging removal is performed; if X is more than 0.52When the plugging rate is less than or equal to 0.7, the plugging is removed in grade II; if 0.2 < X2When the plugging rate is less than or equal to 0.5, the third-level plugging removal is performed; if X2IV grade unblocking is carried out when the plugging rate is less than or equal to 0.2;
the pollution coefficient calculation process is as follows:
s11: determination of initial permeability K of core0；
S12: simulating core pollution;
s13: determination of permeability K after core contamination1；
S14: calculating the contamination coefficient X1：
The calculation process of the acidification and blockage removal coefficient is as follows:
s21: determination of initial permeability K of core0；
S22: simulating core acidizing and unblocking;
s23: measuring permeability K of rock core after acidizing and plugging removal2；
S24: calculating acidification blockage removal coefficient X2：
2. The method for evaluating the testing effect of the testing device for the oilfield injection well pollution blockage relieving experiment according to claim 1, wherein the initial permeability K of the rock core is0The measurement calculation method is as follows:
pouring standard saline water into the middle container (3), loading the rock core (7) into the rock core holder (6), and loading confining pressure on the rock core by using the confining pressure pump (5); will be constant in speedThe constant pressure pump (1) is adjusted to a constant flow Q; after the pressure value of the pressure gauge (4) is stabilized, the pressure is displayed as P3Closing the constant-speed constant-pressure pump (1) and discharging confining pressure;
initial permeability K0Comprises the following steps:
wherein, mu0Is the standard brine viscosity, D is the core diameter, P0Is at standard atmospheric pressure.
3. The method for evaluating the testing effect of the testing device for the oilfield injection well pollution blockage relieving experiment according to claim 1, wherein the core pollution permeability K is1The calculation method is as follows:
pouring standard saline water into the intermediate container (3), and loading the polluted rock core into a rock core holder (6); loading confining pressure on the rock core by using a confining pressure pump (5), and adjusting the constant-speed constant-pressure pump (1) to a constant flow Q; after the pressure value of the pressure gauge (4) is stabilized, the pressure is displayed as P4Closing the constant-speed constant-pressure pump (1) and discharging confining pressure; then K is1Comprises the following steps:
wherein: l is the length of the core, D is the diameter of the core, P4Is a constant speed constant pressure pump pressure value, P0Is at standard atmospheric pressure.
4. The method for evaluating the testing effect of the testing device for the oilfield injection well pollution blockage relieving experiment according to claim 1, wherein the permeability K after core acidizing blockage relieving is high2The calculation method is as follows:
pouring standard saline water into an intermediate container (3), loading the acidized and unplugged rock core into a rock core holder (6), loading confining pressure on the rock core by using a confining pressure pump (5), and adjusting a constant-speed constant-pressure pump (1) to a constant flowQ; after the pressure value of the constant-speed constant-pressure pump (1) is stabilized, the pressure of the pressure gauge is displayed as P5Closing the constant-speed constant-pressure pump (1) and discharging confining pressure; then K is2Comprises the following steps:
wherein: l is the length of the core, D is the diameter of the core, P5Is a constant speed constant pressure pump pressure value, P0Is at standard atmospheric pressure.
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