Experimental device and method for evaluating multi-layer and multi-well-position reservoir water sensitivity

Abstract

The invention relates to an experimental device and method for evaluating multi-layer and multi-well-position reservoir water sensitivity. The experimental device comprises a rock core series-parallel connection and CT scanning unit, a sample unit, a pumping and heating unit and a metering and processing unit. The rock core series-parallel connection and CT scanning unit comprises a CT scanner, a high-level rock core holder group and a low-level rock core holder group, wherein the high-level rock core holder group and the low-level rock core holder group are connected in parallel; the sample unit comprises a first intermediate container, a second intermediate container, a third intermediate container and a gas intermediate container; the pumping and heating unit comprises a vacuum pump, a confining pressure pump, a high-pressure high-precision displacement pump and a coil heater; and the metering and processing unit comprises a computer processing system, a high-level liquid meter and a low-level liquid meter. According to the method, the layer position and well position permeability, porosity and water sensitivity damage rate of injected fluid with different mineralization degrees after the rock core is damaged can be calculated, the water sensitivity of the reservoir rock sample is quantitatively evaluated according to the evaluation index of the water sensitivity damage degree, and a favorable basis is provided for optimizing the injected water mineralization degree.

Description

Technical Field

[0001] The invention relates to a reservoir water sensitivity test device and method for evaluating multiple layers and multiple wells, belonging to the technical field of sensitivity test for oil reservoir water injection development. Background Art

[0002] Water injection development is one of the most commonly used methods to improve crude oil recovery in the world and is widely used in various types of oil reservoirs. With the continuous increase in the exploitation time of oil fields in my country, most oil fields have gradually entered the middle and late stages of exploitation and need to be water injected to supplement the energy of the formation. However, water injection development may cause the interaction between reservoir rocks and injected water, resulting in changes in reservoir property parameters. For example, clay minerals (such as montmorillonite, illite, kaolinite, etc.) in the reservoir will swell, disperse and migrate when encountering water, the chemical composition of the injected water (such as ion type and concentration) does not match the reservoir, and the injection rate causes the migration of clay particles, etc., which will cause the expansion and precipitation reaction of clay minerals, block rock pores and cracks, and reduce permeability. Existing technology cannot accurately simulate the degree of water sensitivity damage to reservoirs at different layers and well locations during water injection development. In order to accurately evaluate whether reservoir rocks are water-sensitive and the strength of water sensitivity, understand the degree of damage to the porosity and permeability of reservoirs during water injection development, and determine a reasonable water injection rate and pressure to reduce the damage to the reservoir caused by water sensitivity, an experimental device and method for evaluating reservoir water sensitivity at multiple layers and multiple well locations is needed. Summary of the invention

[0003] In order to overcome the defects in the prior art, the present invention aims to provide a reservoir water sensitivity test device and method for evaluating multiple layers and multiple wells.

[0004] The technical solution provided by the present invention to solve the above technical problems is: an experimental device for evaluating reservoir water sensitivity of multiple layers and multiple wells, including a core series-parallel and CT scanning unit, a sample unit, a pumping and heating unit, and a metering and processing unit;

[0005] The core series-parallel and CT scanning unit comprises an X-ray detector, a CT scanner, an inlet three-way valve, a vacuum three-way valve, a first vacuum four-way valve, a second vacuum four-way valve, and two parallel high-level core clamp groups and a low-level core clamp group. The X-ray detector is installed in the CT scanner. The high-level core clamp group comprises a first core clamp, a second core clamp, and a third core clamp connected in series in sequence. The low-level core clamp group comprises a fourth core clamp, a fifth core clamp, and a sixth core clamp connected in series in sequence. The first core clamp and the fourth core clamp are connected to the inlet three-way valve. The vacuum three-way valve is connected to the first core clamp, the fourth core clamp, and the first vacuum four-way valve respectively. The first vacuum four-way valve is connected to the second core clamp, the fifth core clamp, and the second vacuum four-way valve respectively. The second vacuum four-way valve is connected to the third core clamp and the sixth core clamp respectively.

[0006] The sample unit comprises a first intermediate container, a second intermediate container, a third intermediate container, an upper four-way valve, and a lower four-way valve, wherein the upper four-way valve is respectively connected to the inlet three-way valve and the upper ends of the first intermediate container, the second intermediate container, and the third intermediate container, and the lower four-way valve is respectively connected to the lower ends of the first intermediate container, the second intermediate container, and the third intermediate container;

[0007] The pumping and heating unit includes a vacuum pump, a confining pressure pump, a high-pressure high-precision displacement pump, a vacuum third four-way valve, and a coil heater; the high-pressure high-precision displacement pump is connected to the lower four-way valve; the confining pressure pump is connected to the vacuum second four-way valve; the vacuum third four-way valve is connected to the vacuum pump; the high-level core clamp group and the low-level core clamp group are both provided with a heating belt electrically connected to the coil heater;

[0008] The metering and processing unit includes a computer processing system, a high-level back pressure valve, a low-level back pressure valve, a high-level liquid meter, and a low-level liquid meter; the two ends of the high-level back pressure valve are respectively connected to the third core clamp and the high-level liquid meter, the low-level back pressure valve is respectively connected to the sixth core clamp and the low-level liquid meter, the third vacuum four-way valve is respectively connected to the high-level back pressure valve and the low-level back pressure valve; the computer processing system is respectively electrically connected to the X-ray detector and the CT scanner.

[0009] A further technical solution is that the sample unit further includes a gas intermediate container, the pumping and heating unit further includes a displacement pump, and both ends of the gas intermediate container are respectively connected to the third vacuum four-way valve and the displacement pump.

[0010] A further technical solution is that a first high-level pressure gauge, a second high-level pressure gauge, a third high-level pressure gauge, and a fourth high-level pressure gauge are respectively provided between the inlet three-way valve and the first core clamp, the first core clamp and the second core clamp, the second core clamp and the third core clamp, and the third core clamp and the high-level back pressure valve; a first low-level pressure gauge, a second low-level pressure gauge, a third low-level pressure gauge, and a fourth low-level pressure gauge are respectively provided between the inlet three-way valve and the fourth core clamp, the fourth core clamp and the fifth core clamp, the fifth core clamp and the sixth core clamp, and the sixth core clamp and the low-level back pressure valve.

[0011] A further technical solution is that a high-level viscosity measuring instrument is provided between the fourth high-level pressure gauge and the high-level back pressure valve, and a low-level viscosity measuring instrument is provided between the fourth low-level pressure gauge and the low-level back pressure valve.

[0012] A further technical solution is that a first high-level inlet check valve, a second high-level inlet check valve, a third high-level inlet check valve, and a fourth high-level outlet check valve are respectively provided between the first high-level pressure gauge and the first core holder, the second high-level pressure gauge and the second core holder, the third high-level pressure gauge and the third core holder, and the fourth high-level pressure gauge and the high-level viscosity measuring instrument;

[0013] A first low-level inlet one-way valve, a second low-level inlet one-way valve, a third low-level inlet one-way valve, and a fourth low-level outlet one-way valve are respectively provided between the first low-level pressure gauge and the fourth core clamp, the second low-level pressure gauge and the fifth core clamp, the third low-level pressure gauge and the sixth core clamp, and the fourth low-level pressure gauge and the low-level viscosity measuring instrument.

[0014] A further technical solution is that the first intermediate container is provided with a first inlet control valve and a first outlet control valve at both ends; the second intermediate container is provided with a second inlet control valve and a second outlet control valve at both ends; the third intermediate container is provided with a third inlet control valve and a third outlet control valve at both ends; and the gas intermediate container is provided with a gas inlet control valve and a gas outlet control valve at both ends.

[0015] A further technical solution is that a gas pressure gauge is provided between the gas intermediate container and the third vacuum four-way valve, a confining pressure gauge and a confining pressure check valve are provided between the confining pressure pump and the second vacuum four-way valve; a vacuum pressure gauge and a vacuum check valve are provided between the vacuum pump and the third vacuum four-way valve.

[0016] A further technical solution is that a high-level liquid meter inlet check valve and a high-level liquid meter pressure gauge are provided between the high-level liquid meter and the high-level back pressure valve; a low-level liquid meter inlet check valve and a low-level liquid meter pressure gauge are provided between the low-level liquid meter and the low-level back pressure valve.

[0017] An experimental method for evaluating reservoir water sensitivity at multiple layers and multiple wells comprises the following steps:

[0018] Step 1: wash the oil and salt from three cores sampled from the same layer and three cores sampled from different layers, dry them at high temperature, measure the basic physical property parameters, and then put the clean and dry cores into the high-layer core holder group and the low-layer core holder group;

[0019] Step 2, preparing three types of salinity salt water, respectively, loading salinity with the salinity of the original formation water into the first intermediate container, loading salinity with half the salinity of the original formation water into the second intermediate container, loading deionized water into the third intermediate container, and compressing nitrogen at the formation pressure into the gas intermediate container through a compressor;

[0020] Step 3: Use a vacuum pump to evacuate the core and pipeline in the holder for more than 12 hours, and use a coil heater to wrap the 6 holders with a heating belt to heat the core to the formation temperature for more than 12 hours; the CT value of the air at this time is calculated by the CT scanner and the computer processing system. air ; Then, the confining pressure is set for the two sets of series-connected clamps according to the reservoir layer pressure. First, a low confining pressure is set for the high layer, and then a high confining pressure is set for the low layer and maintained at a constant pressure. After the confining pressure is stable, the CT value of each dry core is measured by a CT scanner and a computer processing system. dryj and the CT value of brine with half the mineralization of the original formation water mw , and conduct a full-scale scan of each section of each dry core, and use a computer processing system to process the core section image to obtain the pore throat diameter distribution curve and the core three-dimensional reconstruction image;

[0021] Step 4: Pumping brine with original formation water salinity at a pressure lower than the confining pressure into two sets of series cores at a constant pressure;

[0022] Step 5, slowly add back pressure to the high-level clamp, and then add back pressure to the low-level clamp; when the pressures at both ends of the back pressure valve are basically the same, open the fourth high-level outlet check valve and the fourth low-level outlet check valve, observe the pressure gauges at the inlet and outlet of the two sets of series-connected clamps, and after the inlet and outlet pressure difference is stable, displace 10 to 15 times the pore volume of the two sets of series-connected cores through the high-level liquid meter and the low-level liquid meter, and then stop displacing;

[0023] Step 6: Measure the flow rate Q of high-level brine respectively i1 and viscosity μi1 , the flow rate of low-level brine Q i2 and viscosity μ i2 The CT values ​​of the six cores saturated with the initial fluid were determined by a CT scanner and a computer processing system. ij , record the inlet pressure P1 and outlet pressure P2 of core 1, the inlet pressure P2 and outlet pressure P3 of core 2, the inlet pressure P3 and outlet pressure P4 of core 3, the inlet pressure P5 and outlet pressure P6 of core 4, the inlet pressure P6 and outlet pressure P7 of core 5, the inlet pressure P7 and outlet pressure P8 of core 6, and calculate the initial liquid permeability K of the high-level rock sample whj , initial liquid permeability K of low-level rock samples wlj ;

[0024]

[0025] Where: K whj , K wlj are the initial fluid permeability of the high-level and low-level rock samples, mD; Q i1 , Q i2 are the initial fluid flow rates at high and low levels, cm 3 / s; μ i1 , μ i2 are the initial fluid viscosities of the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP ij is the initial fluid core inlet and outlet pressure difference, atm;

[0026] Step 7: Change the injection fluid and pump brine with half the salinity of the original formation water at a constant pressure lower than the confining pressure into the two sets of cores in series;

[0027] Step 8: Use the same method to build pressure for the two groups of cores in series. After the pressure difference between the inlet and outlet is stable, the high-level liquid meter and the low-level liquid meter are used to displace 10 to 15 times the pore volume of the two groups of cores in series, and then the displacement is stopped; keep the confining pressure unchanged, so that the intermediate brine with half the salinity of the original formation water reacts with the core minerals for more than 12 hours, and then drive at a constant pressure until the pressure difference is stable, and measure the flow rate Q of the high-level brine m1 and viscosity μ m1 , the flow rate of low-level brine Q m2 and viscosity μ m2 Similarly, record the inlet and outlet pressures of each core at this time, and calculate the intermediate fluid permeability K of the rock sample after water sensitivity occurs at the high level mhj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj ;

[0028]

[0029] Where: K mhj , K mlj are the intermediate fluid permeabilities of high-level and low-level rock samples, mD; Q m1 , Q m2 are the intermediate fluid flow rates of the high and low layers, cm 3 / s; μ m1 , μ m2 are the viscosity of the intermediate fluid in the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP mj The pressure difference between the inlet and outlet of the test core for the intermediate fluid, atm;

[0030] Step 9: Determine the CT value CT of the saturated intermediate fluid by using a CT scanner and a computer processing system. mj Cross-section scanning was performed on the rock samples with water sensitivity to observe the changes in the pore throat diameter and the distribution of clay minerals after water sensitivity; the core porosity after water sensitivity damage caused by high-level injection of intermediate fluid was obtained. Core porosity after water-sensitive damage caused by injection of intermediate fluid in low-lying layers And calculate the relative porosity of the core after water-sensitive damage of the intermediate fluid

[0031]

[0032] Where: The core porosity after water-sensitive damage caused by injection of intermediate fluid in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryj is the CT value of the dry core, dimensionless; CT mj is the CT value of the core saturated intermediate fluid, dimensionless; CT mw CT is the CT value of brine with half the mineralization of the original formation water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage by saturated intermediate fluid, %; The core porosity after water-sensitive damage caused by injection of intermediate fluids in high and low layers, %; is the initial porosity of the core, %;

[0033] Step 10: Use the same method to build pressure for the two groups of cores in series. After the pressure difference between the inlet and outlet is stable, use the high-level liquid meter and the low-level liquid meter to displace 10 to 15 times the pore volume of the two groups of cores in series, stop displacement, keep the confining pressure unchanged, allow the deionized water to react with the core minerals for more than 12 hours, and then continue to displace at constant pressure until the pressure difference is stable, and measure the flow rate Q of the high-level deionized water. d1 and viscosity μ d1 , the flow rate of deionized water in the lower layer Q d2 and viscosity μ d2 ; Also record the inlet and outlet pressures of each core at this time, and calculate the permeability K of the rock sample after deionized water is injected into the high-level position and water sensitivity occurs dhj , the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj ;

[0034]

[0035] Where: K dhj , K dlj are the deionized water permeability of high-level and low-level rock samples, mD; Q d1 , Q d2 are the deionized water flow rates at the high and low levels, cm 3 / s; μ d1 , μ d2 are the viscosities of deionized water at high and low levels, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP dj The pressure difference between the inlet and outlet of the test core is deionized water, atm;

[0036] Step 11: Determine the CT value of saturated deionized water by using a CT scanner and a computer processing system. dj The rock samples were scanned and image processed to observe the influence of clay expansion and migration in the pores caused by water sensitivity on the overall pore structure, distribution characteristics, and pore coordination number; the core porosity after water sensitivity damage caused by high-level injection of deionized water was obtained. Core porosity after water-sensitive damage caused by injection of deionized water in low-lying layers And calculate the relative porosity of the core after water-sensitive damage by deionized water

[0037]

[0038] Where: The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryjis the CT value of the dry core, dimensionless; CT dj is the CT value of the core saturated with deionized water, dimensionless; CT dw is the CT value of deionized water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage saturated with deionized water, %; The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; is the initial porosity of the core, %;

[0039] Step 12: Based on the initial liquid permeability K of the high-level rock sample whj , initial liquid permeability K of low-level rock samples wlj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs at high level mhj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj , the permeability K of the rock sample after water sensitivity caused by injection of deionized water at high level dhj , the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj , respectively calculate the total water sensitivity damage rate of the injection of intermediate fluid and deionized water in the high-level position, the total water sensitivity damage rate and porosity damage rate of the injection of intermediate fluid and deionized water in the low-level position, and judge the water sensitivity of the reservoir by combining the initial permeability, porosity and water sensitivity damage evaluation index of the reservoir layer;

[0040] The total water-sensitive damage rate of deionized water injected at high levels is:

[0041]

[0042] The total water-sensitive damage rate of deionized water injected into the lower layer is:

[0043]

[0044] Where: D dh , D dl are the total water-sensitive damage rates of deionized water injected into the high and low layers, %; are the equivalent permeabilities before and after injection of deionized water at the high level, mD; are the equivalent permeabilities of the lower layer before and after deionized water injection, mD; L1, L2, L3, L4, L5, L6 are the lengths of the six cores, cm; K wh1 , K wh2 , K wh3 , K dh1 , K dh2 , K dh3Initial fluid test permeability and deionized water test permeability of high-level core 1, core 2 and core 3, mD; K wl4 , K wl5 , K wl6 , K dl4 , K dl5 , K dl6 Initial fluid test permeability and deionized water test permeability of low-level cores 4, 5 and 6, respectively, mD.

[0045] The present invention has the following beneficial effects:

[0046] 1. Based on CT scanning technology, the pore throat and radius distribution, clay expansion and migration, pore coordination number, etc. of dry samples, saturated intermediate fluids, and rock samples saturated with deionized water are compared with the three-dimensional reconstruction images of the core to qualitatively analyze the degree of damage of the injected water to the pores of single rock samples in different layers and well locations;

[0047] 2. Based on CT scanning technology, the computer calculates the CT value of fluid and rock samples, and quantitatively calculates the porosity and relative porosity of the cores at high and low levels and in the same well after water-sensitive damage;

[0048] 3. Through this device, the permeability and water-sensitive damage rate of different layers and wells after the injection of fluids with different mineralization degrees damaging the core can be calculated, and the water sensitivity of the reservoir rock sample can be quantitatively evaluated according to the water-sensitive damage degree evaluation index, providing a favorable basis for optimizing the mineralization of the injected water. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of the present invention;

[0050] Figure 2 is the equivalent permeability ratio curve of layer 1;

[0051] Figure 3 is the water-sensitive damage rate curve of layer 1;

[0052] Figure 4 is the equivalent permeability ratio curve of layer 2;

[0053] Figure 5 It is the water-sensitive damage rate curve of layer 2;

[0054] Figure 6 This is the pore radius distribution curve before and after water sensitivity of layer 1;

[0055] Figure 7 This is the pore radius distribution curve before and after water sensitivity in layer 2. DETAILED DESCRIPTION

[0056] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] like Figure 1 As shown, a reservoir water sensitivity test device for evaluating multi-layer and multi-well positions of the present invention comprises a core series-parallel connection and CT scanning unit I, a sample unit II, a pumping and heating unit III, and a metering and processing unit IV;

[0058] The core series-parallel and CT scanning unit I comprises an X-ray detector 29, a CT scanner 30, an inlet three-way valve 25, a vacuum three-way valve 26, a vacuum first four-way valve 27, a vacuum second four-way valve 28, and two parallel high-level core clamp groups and a low-level core clamp group. The X-ray detector 29 is installed in the CT scanner 30, and the CT scanner 30 is used to collect the CT value of the core in the core clamp;

[0059] The high-level core clamp group includes a first core clamp 1, a second core clamp 2, and a third core clamp 3 connected in series in sequence, and the low-level core clamp group includes a fourth core clamp 4, a fifth core clamp 5, and a sixth core clamp 6 connected in series in sequence; the first core clamp 1 and the fourth core clamp 4 are connected to the inlet three-way valve 25; the vacuum three-way valve 26 is connected to the first core clamp 1, the fourth core clamp 4, and the first vacuum four-way valve 27 respectively, the first vacuum four-way valve 27 is connected to the second core clamp 2, the fifth core clamp 5, and the second vacuum four-way valve 28 respectively, and the second vacuum four-way valve 28 is connected to the third core clamp 3 and the sixth core clamp 6 respectively;

[0060] The sample unit II comprises a first intermediate container 31, a second intermediate container 32, a third intermediate container 33, an upper four-way valve 44, and a lower four-way valve 43. The first intermediate container 31 contains salt water with a salinity of the original formation water, the second intermediate container 32 contains salt water with a salinity of half the original formation water, and the third intermediate container 33 contains deionized water. The upper part of the intermediate container is all samples, and the lower part is hydraulic oil, which is driven by a displacement pump to push the piston for displacement;

[0061] The upper four-way valve 44 is connected to the inlet three-way valve 25 and the upper ends of the first intermediate container 31, the second intermediate container 32, and the third intermediate container 33, respectively, and the lower four-way valve 43 is connected to the lower ends of the first intermediate container 31, the second intermediate container 32, and the third intermediate container 33, respectively;

[0062] The pumping and heating unit III includes a vacuum pump 48, a confining pressure pump 47, a high-pressure and high-precision displacement pump 45, a third vacuum four-way valve 55, and a coil heater 50; the high-pressure and high-precision displacement pump 45 is connected to the lower four-way valve 43; the confining pressure pump 47 is connected to the second vacuum four-way valve 28; the third vacuum four-way valve 55 is connected to the vacuum pump 48; the high-level core clamp group and the low-level core clamp group are both provided with a heating belt electrically connected to the coil heater 50; the confining pressure pump 47 is a constant pressure excitation pump, which is used to provide confining pressure to the clamp;

[0063] The metering and processing unit IV includes a computer processing system 56, a high-level back pressure valve 57, a low-level back pressure valve 58, a high-level liquid meter 64, and a low-level liquid meter 63; the computer processing system 56 is used to calculate the CT scan value of the core and process the reconstructed image; the high-level back pressure valve 57 and the low-level back pressure valve 58 are two serial core outlet back pressure valves, which are used to simulate the formation conditions to provide the clamp with outlet back pressure; the high-level liquid meter 64 and the low-level liquid meter 63 are used to accurately measure the serial core outlet flow;

[0064] The two ends of the high-level back pressure valve 57 are respectively connected to the third core clamp 3 and the high-level liquid meter 64, the low-level back pressure valve 58 is respectively connected to the sixth core clamp 6 and the low-level liquid meter 63, the third vacuum four-way valve 55 is respectively connected to the high-level back pressure valve 57 and the low-level back pressure valve 58; the computer processing system 56 is respectively electrically connected to the X-ray detector 29 and the CT scanner 30.

[0065] like Figure 1 As shown, in order to facilitate the vacuuming of the core holder in this embodiment, a preferred implementation is that the sample unit II also includes a gas intermediate container 34, the gas intermediate container 34 contains nitrogen, and the pumping and heating unit III also includes a displacement pump 46, and the two ends of the gas intermediate container 34 are respectively connected to the third vacuum four-way valve 55 and the displacement pump 46.

[0066] like Figure 1As shown, in order to facilitate monitoring of the pressure of each clamp in the present embodiment, a first high-level pressure gauge 7, a second high-level pressure gauge 11, a third high-level pressure gauge 15, and a fourth high-level pressure gauge 19 are respectively provided between the inlet three-way valve 25 and the first core clamp 1, the first core clamp 1 and the second core clamp 2, the second core clamp 2 and the third core clamp 3, and the third core clamp 3 and the high-level back pressure valve 57; a first low-level pressure gauge 8, a second low-level pressure gauge 12, a third low-level pressure gauge 16, and a fourth low-level pressure gauge 20 are respectively provided between the inlet three-way valve 25 and the fourth core clamp 4, the fourth core clamp 4 and the fifth core clamp 5, the fifth core clamp 5 and the sixth core clamp 6, and the sixth core clamp 6 and the low-level back pressure valve 58.

[0067] like Figure 1 As shown, in this embodiment, in order to measure viscosity, the preferred implementation method is that a high-level viscosity measuring instrument 23 is provided between the fourth high-level pressure gauge 19 and the high-level back pressure valve 57, and a low-level viscosity measuring instrument 24 is provided between the fourth low-level pressure gauge 20 and the low-level back pressure valve 58.

[0068] like Figure 1 As shown, a first high-level inlet check valve 9, a second high-level inlet check valve 13, a third high-level inlet check valve 17, and a fourth high-level outlet check valve 21 are respectively provided between the first high-level pressure gauge 7 and the first core holder 1, the second high-level pressure gauge 11 and the second core holder 2, the third high-level pressure gauge 15 and the third core holder 3, and the fourth high-level pressure gauge 19 and the high-level viscosity measuring instrument 23;

[0069] A first low-level inlet one-way valve 10, a second low-level inlet one-way valve 14, a third low-level inlet one-way valve 18, and a fourth low-level outlet one-way valve 22 are respectively provided between the first low-level pressure gauge 8 and the fourth core clamp 4, the second low-level pressure gauge 12 and the fifth core clamp 5, the third low-level pressure gauge 16 and the sixth core clamp 6, and the fourth low-level pressure gauge 20 and the low-level viscosity measuring instrument 24.

[0070] The first intermediate container 31 is provided with a first inlet control valve 35 and a first outlet control valve 39 at both ends; the second intermediate container 32 is provided with a second inlet control valve 36 and a second outlet control valve 40 at both ends; the third intermediate container 33 is provided with a third inlet control valve 37 and a third outlet control valve 41 at both ends; the gas intermediate container 34 is provided with a gas inlet control valve 38 and a gas outlet control valve 42 at both ends.

[0071] A gas pressure gauge 49 is provided between the gas intermediate container 34 and the third vacuum four-way valve 55; a confining pressure gauge 51 and a confining pressure check valve 52 are provided between the confining pressure pump 47 and the second vacuum four-way valve 28; a vacuum pressure gauge 53 and a vacuum check valve 54 are provided between the vacuum pump 48 and the third vacuum four-way valve 55.

[0072] A high-level liquid meter inlet non-return valve 62 and a high-level liquid meter pressure gauge 60 are provided between the high-level liquid meter 64 and the high-level back pressure valve 57; a low-level liquid meter inlet non-return valve 61 and a low-level liquid meter pressure gauge 59 are provided between the low-level liquid meter 63 and the low-level back pressure valve 58.

[0073] An experimental method for evaluating reservoir water sensitivity at multiple layers and multiple wells comprises the following steps:

[0074] Step 1: Wash the oil and salt from three cores sampled from the same layer and three cores sampled from different layers, then dry them at high temperature and measure the basic physical properties (length L j , diameter D j , initial permeability K j , Porosity The clean and dry cores are then loaded into the high-level core holder group and the low-level core holder group;

[0075] Step 2, prepare three types of salinity salt water, respectively put saline with salinity of original formation water into the first intermediate container 31, put saline with half salinity of original formation water into the second intermediate container 32, put deionized water into the third intermediate container 33, and press nitrogen under formation pressure into the gas intermediate container 34 through a compressor;

[0076] Step 3: The core and pipeline in the holder are evacuated by vacuum pump 48 for more than 12 hours, and the core is heated to the formation temperature for more than 12 hours by coil heater 50, using heating tape wrapped around 6 holders; the CT value CT of the air at this time is calculated by CT scanner 30 and computer processing system 56. air Then, the confining pressure is set for the two sets of series-connected clamps according to the reservoir layer pressure. The low confining pressure is set for the high layer first, and then the high confining pressure is set for the low layer and maintained at a constant pressure. After the confining pressure is stable, the CT value CT of each dry core is measured by the CT scanner 30 and the computer processing system 56. dryj (j = 1 to 6) and the CT value of salt water with half the mineralization of the original formation water mw , and all sections of each dry core are scanned in all directions, and the core section images are processed by the computer processing system 56 to obtain the curve of pore throat diameter distribution and the three-dimensional reconstruction image of the core;

[0077] Step 4: Pumping brine with original formation water salinity at a pressure lower than the confining pressure into two sets of series cores at a constant pressure;

[0078] Step 5, slowly add back pressure to the high-level clamp, and then add back pressure to the low-level clamp; when the pressures at both ends of the back pressure valve are basically the same, open the fourth high-level outlet check valve 21 and the fourth low-level outlet check valve 22, observe the pressure gauges at the inlet and outlet of the two groups of series-connected clamps, and after the inlet and outlet pressure difference is stable, displace 10 to 15 times the pore volume of the two groups of series-connected cores through the high-level liquid meter 64 and the low-level liquid meter 63, and then stop displacing;

[0079] Step 6: Measure the flow rate Q of high-level brine respectively i1 and viscosity μ i1 , the flow rate of low-level brine Q i2 and viscosity μ i2 , and the CT values ​​of the six cores saturated with the initial fluid are determined by the CT scanner 30 and the computer processing system 56 ij (j=1-6), record the inlet pressure P1 and outlet pressure P2 of core 1, the inlet pressure P2 and outlet pressure P3 of core 2, the inlet pressure P3 and outlet pressure P4 of core 3, the inlet pressure P5 and outlet pressure P6 of core 4, the inlet pressure P6 and outlet pressure P7 of core 5, the inlet pressure P7 and outlet pressure P8 of core 6, and let ΔP i1 =P1-P2, ΔP i2 =P2-P3, ΔP i3 =P3-P4, ΔP i4 =P5-P6, ΔP i5 =P6-P7, ΔP i6 = P7-P8 Calculate the initial liquid permeability K of the high-level rock sample whj (j=1-3), initial liquid permeability K of the lower layer rock sample wlj (j=4-6);

[0080]

[0081] Where: K whj , K wlj are the initial fluid permeability of the high-level and low-level rock samples, mD; Q i1 , Q i2 are the initial fluid flow rates at high and low levels, cm 3 / s; μ i1 , μ i2 are the initial fluid viscosities of the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP ijis the initial fluid core inlet and outlet pressure difference, atm;

[0082] Step 7: Change the injection fluid and pump brine with half the salinity of the original formation water at a constant pressure lower than the confining pressure into the two sets of cores in series;

[0083] Step 8: Use the same method to build pressure for the two groups of series cores. After the pressure difference between the inlet and outlet is stable, the high-level liquid meter 64 and the low-level liquid meter 63 are used to displace 10 to 15 times the pore volume of the two groups of series cores, and then stop the displacement; keep the confining pressure unchanged, so that the intermediate brine with half the salinity of the original formation water reacts with the core minerals for more than 12 hours, and then displace at a constant pressure until the pressure difference is stable, and measure the flow rate Q of the high-level brine m1 and viscosity μ m1 , the flow rate of low-level brine Q m2 and viscosity μ m2 Similarly, record the pressures P1, P2, P3, P4, P5, P6, P7, and P8 at this time, and let ΔP m1 =P1-P2, ΔP m2 =P2-P3, ΔP m3 =P3-P4, ΔP m4 =P5-P6, ΔP m5 =P6-P7, ΔP m6 = P7-P8 Calculate the intermediate fluid permeability K of the rock sample after water sensitivity occurs at the high level mhj (j=1-3), the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj (j=4-6);

[0084]

[0085] Where: K mhj , K mlj are the intermediate fluid permeabilities of high-level and low-level rock samples, mD; Q m1 , Q m2 are the intermediate fluid flow rates of the high and low layers, cm 3 / s; μ m1 , μ m2 are the viscosity of the intermediate fluid in the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP mj The pressure difference between the inlet and outlet of the test core for the intermediate fluid, atm;

[0086] Step 9: Determine the CT value CT of the saturated intermediate fluid by using the CT scanner 30 and the computer processing system 56. mj(j=1-6) Cross-section scanning is performed on rock samples that are water sensitive to observe the changes in pore throat diameter and the distribution of clay minerals after water sensitivity; the core porosity after water sensitivity damage caused by high-level injection of intermediate fluid is obtained. (j=1-3), core porosity after water-sensitive damage caused by injection of intermediate fluid in low-lying layers And calculate the relative porosity of the core after water-sensitive damage of the intermediate fluid

[0087]

[0088] Where: The core porosity after water-sensitive damage caused by injection of intermediate fluid in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryj is the CT value of the dry core, dimensionless; CT mj is the CT value of the core saturated intermediate fluid, dimensionless; CT mw CT is the CT value of brine with half the mineralization of the original formation water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage by saturated intermediate fluid, %; The core porosity after water-sensitive damage caused by injection of intermediate fluids in high and low layers, %; is the initial porosity of the core, %;

[0089] Step 10: Use the same method to build pressure for the two groups of series cores. After the pressure difference between the inlet and outlet is stable, the high-level liquid meter 64 and the low-level liquid meter 63 are used to displace 10 to 15 times the pore volume of the two groups of series cores, respectively, and then stop the displacement, keep the confining pressure unchanged, and allow the deionized water to react with the core minerals for more than 12 hours. Then, the constant pressure is displaced until the pressure difference is stable, and the flow rate Q of the high-level deionized water is measured. d1 and viscosity μ d1 , the flow rate of deionized water in the lower layer Q d2 and viscosity μ d2 ; Record the pressures P1, P2, P3, P4, P5, P6, P7, P8 at this time, and let ΔP d1 =P1-P2, ΔP d2 =P2-P3, ΔP d3 =P3-P4, ΔP d4 =P5-P6, ΔP d5 =P6-P7, ΔP d6 = P7-P8, calculate the permeability K of the rock sample after water sensitivity occurs due to deionized water injection at high level dhj (j=1-3), the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj (j=4-6);

[0090]

[0091]

[0092] Where: K dhj , K dlj are the deionized water permeability of high-level and low-level rock samples, mD; Q d1 , Q d2 are the deionized water flow rates at the high and low levels, cm 3 / s; μ d1 , μ d2 are the viscosities of deionized water at high and low levels, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP dj The pressure difference between the inlet and outlet of the test core is deionized water, atm;

[0093] Step 11: The CT value CT of saturated deionized water is measured by the CT scanner 30 and the computer processing system 56. dj (j=1-6), cross-section scanning and image processing were performed on the rock samples to observe the influence of clay expansion and migration in the pores caused by water sensitivity on the overall pore structure, distribution characteristics, and pore coordination number; the core porosity after water sensitivity damage caused by high-level injection of deionized water was obtained to be Core porosity after water-sensitive damage caused by injection of deionized water in low-lying layers And calculate the relative porosity of the core after water-sensitive damage by deionized water

[0094]

[0095] Where: The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryj is the CT value of the dry core, dimensionless; CT dj is the CT value of the core saturated with deionized water, dimensionless; CT dw is the CT value of deionized water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage saturated with deionized water, %; The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; is the initial porosity of the core, %;

[0096] Therefore, the total water-sensitive porosity after injection of intermediate fluid at high level is The porosity after water-sensitive total damage by injection of deionized water is The total porosity after water-sensitive damage caused by injection of intermediate fluid in the lower layer is The porosity after water-sensitive total damage by injection of deionized water is The porosity after water-sensitive total damage after injection of intermediate fluid in the same well is The porosity after water-sensitive total damage by injection of deionized water is

[0097] Step 12: Based on the initial liquid permeability K of the high-level rock sample whj (j = 1-3), initial liquid permeability K of the lower layer rock sample wlj (j=4-6), the intermediate fluid permeability K of the rock sample after water sensitivity occurs at the high level mhj (j=1-3), the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj (j=4-6), permeability K of rock sample after water sensitivity occurs after deionized water is injected into high-level dhj (j=1-3), the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj (j=4-6), respectively calculate the total water sensitivity damage rate of the injection of intermediate fluid and deionized water in the high-level position, the total water sensitivity damage rate and porosity damage rate of the injection of intermediate fluid and deionized water in the low-level position, and judge the water sensitivity of the reservoir by combining the initial permeability, porosity and water sensitivity damage evaluation index of the reservoir layer;

[0098] According to the water sensitivity damage rate formula:

[0099]

[0100] Where: D w is the water sensitivity damage rate, %; K w is the permeability of the original formation water, mD; K s Permeability measured for fluids with different salinities, mD.

[0101] Water-sensitive damage rate of high-level deionized water (j=1~3):

[0102]

[0103] Where: D dhj is the water sensitivity damage rate of high-level deionized water, %; K whj , K dhj are the initial fluid test permeability and deionized water test permeability of high-level rock samples, mD; Q i1 , Q d1 are the initial fluid flow rate and deionized water flow rate at the high level, cm3 / s; μ i1 , μ d1 are the initial fluid flow viscosity at the high level and the viscosity of deionized water, mPa·s; ΔP ij , ΔP dj are the core inlet and outlet pressure differences of the high-level initial fluid and deionized water tests, atm;

[0104] Water-sensitive damage rate of low-level deionized water (j=4-6):

[0105]

[0106] Where: D dlj is the water sensitivity damage rate of deionized water in the lower layer, %; K wlj , K dhj are the initial fluid test permeability and deionized water test permeability of the lower layer rock sample, mD; Q i2 , Q d2 are the initial fluid flow rate and deionized water flow rate of the lower layer, cm 3 / s; μ i2 , μ d2 are the initial fluid flow viscosity and deionized water viscosity of the lower layer, mPa·s; ΔP ij , ΔP dj are the core inlet and outlet pressure differences of the initial fluid and deionized water tests at the lower layer, atm;

[0107] According to the series formation permeability harmonic average formula, the equivalent permeability before deionized water injection at the high level is:

[0108]

[0109] The equivalent permeability after water-sensitive damage caused by injection of deionized water at high levels is:

[0110]

[0111] Where: are the equivalent permeabilities before and after injection of deionized water at the high level, mD; L1, L2, L3 are the lengths of core 1, core 2, and core 3, cm; K wh1 , K wh2 , K wh3 The initial fluid test permeability of high-level core 1, core 2 and core 3, mD; K dh1 , K dh2 , K dh3 The deionized water test permeability of core 1, core 2 and core 3 at high level, mD;

[0112] The total water-sensitive damage rate of deionized water injected at high levels is:

[0113]

[0114] Similarly, the total water-sensitive damage rate of deionized water injected into the lower layer is:

[0115]

[0116] Where: D dh , D dl are the total water-sensitive damage rates of deionized water injected into the high and low layers, %; are the equivalent permeabilities before and after injection of deionized water at the high level, mD; are the equivalent permeabilities of the lower layer before and after deionized water injection, mD; L1, L2, L3, L4, L5, L6 are the lengths of the six cores, cm; K wh1 , K wh2 , K wh3 , K dh1 , K dh2 , K dh3 Initial fluid test permeability and deionized water test permeability of high-level core 1, core 2 and core 3, mD; K wl4 , K wl5 , K wl6 , K dl4 , K dl5 , K dl6 The initial fluid test permeability and deionized water test permeability of the lower layer core 4, core 5 and core 6, respectively, mD;

[0117] Example

[0118] A tight sandstone reservoir has a reservoir pressure of 56.3MPa, a reservoir temperature of 73℃, a burial depth of 5214-5378m, a formation water mineralization of 29756mg / L, an average reservoir porosity of 5.23%, and an average permeability of 0.01349mD. The initial design of the reservoir is to carry out fracturing depletion development in the early stage and water injection energy replenishment development in the middle and late stages. Sampling was carried out at two layers and three wells of the reservoir for water sensitivity experimental evaluation to clarify the water sensitivity of the reservoir and the suitability of water injection development. The basic porosity and permeability of the sampled cores are as follows:

[0119] Table 1 Basic parameters of core

[0120]

[0121]

[0122] According to the device and method, the equivalent permeability ratio curve of layer 1 is obtained as follows: Figure 2 As shown in the water sensitivity injury rate curve Figure 3 As shown in Figure 2, the equivalent permeability ratio curve of layer 2 is as follows: Figure 4 As shown in the water sensitivity injury rate curve Figure 5 As shown in the figure, the water sensitivity damage rate of layer 1 is 28.56%, which is weak water sensitivity; the water sensitivity damage rate of layer 2 is 31.33%, which is moderately weak water sensitivity, and belongs to weak-moderately weak water sensitivity reservoir.

[0123] The relative porosity of layer 1 after deionized water injection is calculated from the CT value of CT scanning to be 86.16%, and the relative porosity of layer 2 is 82.79%. The pore radius distribution curves of layer 1 and layer 2 before and after water sensitivity are shown in Figure 2. Figure 6 , 7 As shown in the figure, the water-sensitive effect caused by the injection of deionized water reduces the proportion of pores with larger radius in the reservoir, mainly causing blockage damage to pore throats with larger radius, with the proportion reduced by 5-6%.

[0124] Combined with the water-sensitive damage degree of the reservoir's stratum porosity and permeability, it is judged that the reservoir has low water sensitivity and the risk of water injection development is small. Some measures can be taken to mitigate the damage, and water injection development can be considered.

[0125] The above description is not intended to limit the present invention in any form. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are within the scope of the technical solution of the present invention.

Claims

1. A reservoir water sensitivity test device for evaluating multiple layers and multiple wells, characterized in that: It includes a core series-parallel connection and CT scanning unit (I), a sample unit (II), a pumping and heating unit (III), and a metering and processing unit (IV); The core series-parallel and CT scanning unit (I) comprises an X-ray detector (29), a CT scanner (30), an inlet three-way valve (25), a vacuum three-way valve (26), a first vacuum four-way valve (27), a second vacuum four-way valve (28), and two parallel high-level core clamping groups and a low-level core clamping group. The X-ray detector (29) is installed in the CT scanner (30). The high-level core clamping group comprises a first core clamping group (1), a second core clamping group (2), and a third core clamping group (3) which are sequentially connected in series. The low-level core clamping group comprises a fourth core clamping group (3) which are sequentially connected in series. a core holder (4), a fifth core holder (5), and a sixth core holder (6); the first core holder (1) and the fourth core holder (4) are connected to the inlet three-way valve (25); the vacuum three-way valve (26) is connected to the first core holder (1), the fourth core holder (4), and the first vacuum four-way valve (27), respectively; the first vacuum four-way valve (27) is connected to the second core holder (2), the fifth core holder (5), and the second vacuum four-way valve (28), respectively; the second vacuum four-way valve (28) is connected to the third core holder (3) and the sixth core holder (6); The sample unit (II) comprises a first intermediate container (31), a second intermediate container (32), a third intermediate container (33), an upper four-way valve (44), and a lower four-way valve (43); the upper four-way valve (44) is respectively connected to the inlet three-way valve (25) and the upper ends of the first intermediate container (31), the second intermediate container (32), and the third intermediate container (33); and the lower four-way valve (43) is respectively connected to the lower ends of the first intermediate container (31), the second intermediate container (32), and the third intermediate container (33); The pumping and heating unit (III) comprises a vacuum pump (48), a confining pressure pump (47), a high-pressure and high-precision displacement pump (45), a vacuum third four-way valve (55), and a coil heater (50); the high-pressure and high-precision displacement pump (45) is connected to the lower four-way valve (43); the confining pressure pump (47) is connected to the vacuum second four-way valve (28); the vacuum third four-way valve (55) is connected to the vacuum pump (48); the high-level core clamp group and the low-level core clamp group are both provided with a heating belt electrically connected to the coil heater (50); The metering and processing unit (IV) comprises a computer processing system (56), a high-level back pressure valve (57), a low-level back pressure valve (58), a high-level liquid meter (64), and a low-level liquid meter (63); the two ends of the high-level back pressure valve (57) are respectively connected to the third core holder (3) and the high-level liquid meter (64); the low-level back pressure valve (58) is respectively connected to the sixth core holder (6) and the low-level liquid meter (63); the third vacuum four-way valve (55) is respectively connected to the high-level back pressure valve (57) and the low-level back pressure valve (58); the computer processing system (56) is respectively electrically connected to the X-ray detector (29) and the CT scanner (30).

2. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 1, characterized in that: The sample unit (II) further includes a gas intermediate container (34), and the pumping and heating unit (III) further includes a displacement pump (46). Both ends of the gas intermediate container (34) are respectively connected to the third vacuum four-way valve (55) and the displacement pump (46).

3. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 1, characterized in that: A first high-level pressure gauge (7), a second high-level pressure gauge (11), a third high-level pressure gauge (15), and a fourth high-level pressure gauge (19) are respectively provided between the inlet three-way valve (25) and the first core holder (1), between the first core holder (1) and the second core holder (2), between the second core holder (2) and the third core holder (3), and between the third core holder (3) and the high-level back pressure valve (57); a first low-level pressure gauge (8), a second low-level pressure gauge (12), a third low-level pressure gauge (16), and a fourth low-level pressure gauge (20) are respectively provided between the inlet three-way valve (25) and the fourth core holder (4), between the fourth core holder (4) and the fifth core holder (5), between the fifth core holder (5) and the sixth core holder (6), and between the sixth core holder (6) and the low-level back pressure valve (58).

4. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 3, characterized in that: A high-level viscosity measuring instrument (23) is provided between the fourth high-level pressure gauge (19) and the high-level back pressure valve (57), and a low-level viscosity measuring instrument (24) is provided between the fourth low-level pressure gauge (20) and the low-level back pressure valve (58).

5. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 4, characterized in that: A first high-level inlet check valve (9), a second high-level inlet check valve (13), a third high-level inlet check valve (17), and a fourth high-level outlet check valve (21) are respectively provided between the first high-level pressure gauge (7) and the first core holder (1), between the second high-level pressure gauge (11) and the second core holder (2), between the third high-level pressure gauge (15) and the third core holder (3), and between the fourth high-level pressure gauge (19) and the high-level viscosity measuring instrument (23); A first low-level inlet one-way valve (10), a second low-level inlet one-way valve (14), a third low-level inlet one-way valve (18), and a fourth low-level outlet one-way valve (22) are respectively provided between the first low-level pressure gauge (8) and the fourth core holder (4), the second low-level pressure gauge (12) and the fifth core holder (5), the third low-level pressure gauge (16) and the sixth core holder (6), and the fourth low-level pressure gauge (20) and the low-level viscosity measuring instrument (24).

6. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 2, characterized in that: The first intermediate container (31) is provided with a first inlet control valve (35) and a first outlet control valve (39) at both ends; the second intermediate container (32) is provided with a second inlet control valve (36) and a second outlet control valve (40) at both ends; the third intermediate container (33) is provided with a third inlet control valve (37) and a third outlet control valve (41) at both ends; and the gas intermediate container (34) is provided with a gas inlet control valve (38) and a gas outlet control valve (42) at both ends.

7. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 2, characterized in that: A gas pressure gauge (49) is provided between the gas intermediate container (34) and the third vacuum four-way valve (55); a confining pressure gauge (51) and a confining pressure check valve (52) are provided between the confining pressure pump (47) and the second vacuum four-way valve (28); and a vacuum pressure gauge (53) and a vacuum check valve (54) are provided between the vacuum pump (48) and the third vacuum four-way valve (55).

8. The reservoir water sensitivity test device for evaluating multiple layers and multiple wells according to claim 2, characterized in that: A high-level liquid meter inlet non-return valve (62) and a high-level liquid meter pressure gauge (60) are provided between the high-level liquid meter (64) and the high-level back pressure valve (57); a low-level liquid meter inlet non-return valve (61) and a low-level liquid meter pressure gauge (59) are provided between the low-level liquid meter (63) and the low-level back pressure valve (58).

9. An experimental method for evaluating reservoir water sensitivity at multiple layers and multiple wells, characterized in that: The method uses any one of claims 1-8 to evaluate the reservoir water sensitivity of multiple layers and multiple wells to conduct experiments, and specifically includes the following steps: Step 1: wash the oil and salt from three cores sampled from the same layer and three cores sampled from different layers, dry them at high temperature, measure the basic physical property parameters, and then put the clean and dry cores into the high-layer core holder group and the low-layer core holder group; Step 2, preparing three types of salinity salt water, respectively loading salinity salt water with the salinity of the original formation water into the first intermediate container (31), loading salinity salt water with half the salinity of the original formation water into the second intermediate container (32), loading deionized water into the third intermediate container (33), and compressing nitrogen gas at the formation pressure into the gas intermediate container (34) through a compressor; Step 3: The core and pipeline in the holder are evacuated by a vacuum pump (48) for more than 12 hours, and the core is heated to the formation temperature for more than 12 hours by a coil heater (50) and a heating belt is wrapped around the six holders; the CT value CT of the air at this time is calculated by a CT scanner (30) and a computer processing system (56). air Then, the confining pressure is set for the two sets of series-connected clamps according to the reservoir layer pressure, firstly setting a low confining pressure for the high layer, and then setting a high confining pressure for the low layer and maintaining the constant pressure. After the confining pressure is stable, the CT value CT of each dry core is measured by the CT scanner (30) and the computer processing system (56). dryj and the CT value of brine with half the mineralization of the original formation water mw , and scanning each section of each dry core in all directions, and processing the core section image by a computer processing system (56) to obtain a pore throat diameter distribution curve and a three-dimensional reconstructed image of the core; Step 4: Pumping brine with original formation water salinity at a pressure lower than the confining pressure into two sets of series cores at a constant pressure; Step 5, slowly add back pressure to the high-level clamp, and then add back pressure to the low-level clamp; when the pressures at both ends of the back pressure valve are basically the same, open the fourth high-level outlet check valve (21) and the fourth low-level outlet check valve (22), observe the pressure gauges at the inlet and outlet of the two groups of series-connected clamps, and after the inlet and outlet pressure difference is stable, displace 10 to 15 times the pore volume of the two groups of series-connected cores through the high-level liquid meter (64) and the low-level liquid meter (63), and then stop displacing; Step 6: Measure the flow rate Q of high-level brine respectively i1 and viscosity μ i1 , the flow rate of low-level brine Q i2 and viscosity μ i2 The CT values ​​of the six cores saturated with the initial fluid are measured by a CT scanner (30) and a computer processing system (56). ij , record the inlet pressure P1 and outlet pressure P2 of core 1, the inlet pressure P2 and outlet pressure P3 of core 2, the inlet pressure P3 and outlet pressure P4 of core 3, the inlet pressure P5 and outlet pressure P6 of core 4, the inlet pressure P6 and outlet pressure P7 of core 5, the inlet pressure P7 and outlet pressure P8 of core 6, and calculate the initial liquid permeability K of the high-level rock sample whj , initial liquid permeability K of low-level rock samples wlj ; Where: K whj , K wlj are the initial fluid permeability of the high-level and low-level rock samples, mD; Q i1 , Q i2 are the initial fluid flow rates at high and low levels, cm 3 / s; μ i1 , μ i2 are the initial fluid viscosities of the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP ij is the initial fluid core inlet and outlet pressure difference, atm; Step 7: Change the injection fluid and pump brine with half the salinity of the original formation water at a constant pressure lower than the confining pressure into the two sets of cores in series; Step 8: Use the same method to build up pressure for the two groups of cores in series. After the pressure difference between the inlet and outlet is stable, the high-level liquid meter (64) and the low-level liquid meter (63) are used to displace 10 to 15 times the pore volume of the two groups of cores in series, and then stop the displacement; keep the confining pressure unchanged, so that the intermediate brine with half the salinity of the original formation water reacts with the core minerals for more than 12 hours, and then displace at a constant pressure until the pressure difference is stable, and measure the flow rate Q of the high-level brine m1 and viscosity μ m1 , the flow rate of low-level brine Q m2 and viscosity μ m2 Similarly, record the inlet and outlet pressures of each core at this time, and calculate the intermediate fluid permeability K of the rock sample after water sensitivity occurs at the high level mhj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj ; Where: K mhj , K mlj are the intermediate fluid permeabilities of high-level and low-level rock samples, mD; Q m1 , Q m2 are the intermediate fluid flow rates of the high and low layers, cm 3 / s; μ m1 , μ m2 are the viscosity of the intermediate fluid in the high and low layers, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP mj The pressure difference between the inlet and outlet of the test core for the intermediate fluid, atm; Step 9: Determine the CT value CT of the saturated intermediate fluid by using the CT scanner (30) and the computer processing system (56). mj Cross-section scanning was performed on the rock samples with water sensitivity to observe the changes in the pore throat diameter and the distribution of clay minerals after water sensitivity; the core porosity after water sensitivity damage caused by high-level injection of intermediate fluid was obtained. Core porosity after water-sensitive damage caused by injection of intermediate fluid in low-lying layers And calculate the relative porosity of the core after water-sensitive damage of the intermediate fluid Where: The core porosity after water-sensitive damage caused by injection of intermediate fluid in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryj is the CT value of the dry core, dimensionless; CT mj is the CT value of the core saturated intermediate fluid, dimensionless; CT mw CT is the CT value of brine with half the mineralization of the original formation water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage by saturated intermediate fluid, %; The core porosity after water-sensitive damage caused by injection of intermediate fluids in high and low layers, %; is the initial porosity of the core, %; Step 10: Use the same method to build up pressure for the two groups of cores in series. After the pressure difference between the inlet and outlet is stable, the high-level liquid meter (64) and the low-level liquid meter (63) are used to displace 10 to 15 times the pore volume of the two groups of cores in series, and then stop the displacement, keep the confining pressure unchanged, and allow the deionized water to react with the core minerals for more than 12 hours. Then, the constant pressure is displaced until the pressure difference is stable, and the flow rate Q of the high-level deionized water is measured. d1 and viscosity μ d1 , the flow rate of deionized water in the lower layer Q d2 and viscosity μ d2 ; Also record the inlet and outlet pressures of each core at this time, and calculate the permeability K of the rock sample after deionized water is injected into the high-level position and water sensitivity occurs dhj , the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj ; Where: K dhj , K dlj are the deionized water permeability of high-level and low-level rock samples, mD; Q d1 , Q d2 are the deionized water flow rates at the high and low levels, cm 3 / s; μ d1 , μ d2 are the viscosities of deionized water at high and low levels, mPa·s; L j is the core length, cm; D j is the core diameter, cm; ΔP dj The pressure difference between the inlet and outlet of the test core is deionized water, atm; Step 11: Determine the CT value CT of saturated deionized water by using a CT scanner (30) and a computer processing system (56). dj The rock samples were scanned and image processed to observe the influence of clay expansion and migration in the pores caused by water sensitivity on the overall pore structure, distribution characteristics, and pore coordination number; the core porosity after water sensitivity damage caused by high-level injection of deionized water was obtained. Core porosity after water-sensitive damage caused by injection of deionized water in low-lying layers And calculate the relative porosity of the core after water-sensitive damage by deionized water Where: The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; CT ij is the CT value of the initial fluid saturated with the core, dimensionless; CT dryj is the CT value of the dry core, dimensionless; CT dj is the CT value of the core saturated with deionized water, dimensionless; CT dw is the CT value of deionized water, dimensionless; CT air is the CT value of air at formation temperature, dimensionless; is the relative porosity of the core after water-sensitive damage saturated with deionized water, %; The core porosity after water-sensitive damage caused by injection of deionized water in high and low layers, %; is the initial porosity of the core, %; Step 12: Based on the initial liquid permeability K of the high-level rock sample whj , initial liquid permeability K of low-level rock samples wlj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs at high level mhj , the intermediate fluid permeability K of the rock sample after water sensitivity occurs in the lower layer mlj , the permeability K of the rock sample after water sensitivity caused by injection of deionized water at high level dhj , the permeability K of the rock sample after deionization in the lower layer caused water sensitivity dlj , respectively calculate the total water sensitivity damage rate of the injection of intermediate fluid and deionized water in the high-level position, the total water sensitivity damage rate and porosity damage rate of the injection of intermediate fluid and deionized water in the low-level position, and judge the water sensitivity of the reservoir by combining the initial permeability, porosity and water sensitivity damage evaluation index of the reservoir layer; The total water-sensitive damage rate of deionized water injected at high levels is: The total water-sensitive damage rate of deionized water injected into the lower layer is: Where: D dh , D dl are the total water-sensitive damage rates of deionized water injected into the high and low layers, %; are the equivalent permeabilities before and after injection of deionized water at the high level, mD; are the equivalent permeabilities of the lower layer before and after deionized water injection, mD; L1, L2, L3, L4, L5, L6 are the lengths of the six cores, cm; K wh1 , K wh2 , K wh3 , K dh1 , K dh2 , K dh3 Initial fluid test permeability and deionized water test permeability of high-level core 1, core 2 and core 3, mD; K wl4 , K wl5 , K wl6 , K dl4 , K dl5 , K dl6 Initial fluid test permeability and deionized water test permeability of low-level cores 4, 5 and 6, respectively, mD.

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