Experimental device and experimental method for simulating gas reservoir multi-layer commingling production

Abstract

The experimental device comprises a gas storage unit and a shaft inserted into the gas storage unit, the gas storage unit is of a hollow structure, one end of the shaft extends into the gas storage unit to the bottom of the gas storage unit, and the other end of the shaft is communicated with an external gas source through a flow control valve. The flow control valve is connected with a gas flow meter and a pressure sensor, and a plurality of transverse simulation gas storage layers are arranged in the gas storage unit; according to the experimental device and the experimental method for simulating gas reservoir multi-layer commingling production, gas flow channels of different reservoir combinations are established by changing different screw-in positions of the gas production shaft, and gas transmission pipelines of all the simulated gas reservoirs are relatively independent, so that the multi-layer commingling production process of the gas reservoir is simulated, all the gas reservoirs of the gas reservoir are selectively developed, and the experimental efficiency is improved. And in the implementation process, each gas reservoir can have uniform pressure which is matched with the actual gas reservoir development condition.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir recovery rate, relates to an experimental device for simulating multi-layer combined production of gas reservoirs, and also relates to an experimental method for simulating multi-layer combined production of gas reservoirs. Background Art

[0002] Generally speaking, there are multiple reservoirs in an oil and gas pool. During the entire development process, in order to increase the utilization of reserves and achieve economical and efficient development, a multi-layer combined production method is adopted.

[0003] Multi-layer commingled production of gas reservoirs is also one of the effective means to control water invasion profiles. On the one hand, the production pressure difference of the low permeability layer can be increased, the flow rate of the fluid in the low permeability layer can be increased, and the liquid production profile can be accelerated; on the other hand, the production pressure difference of the high permeability layer can be reduced, so that the forward speed of the liquid production profile slows down and eventually becomes equal to the liquid production profile of the low permeability layer, thereby minimizing the adverse effects of gas reservoir water invasion on the recovery rate. Therefore, an experimental device and method are urgently needed to simulate the multi-layer commingled production process of gas reservoirs.

[0004] At present, there are many studies on the physical simulation of water invasion process in water-bearing gas reservoirs, such as using multiple core holders in parallel or series to study its water invasion dynamics, but this does not match the actual situation that each gas-producing layer has a uniform pressure during gas reservoir development, which, to a certain extent, reduces the guiding role of its experimental results in production practice. Few scholars have deeply explored the devices and methods of multi-layer combined production in the process of gas reservoir simulation development. Summary of the invention

[0005] The purpose of the present invention is to provide an experimental device for simulating multi-layer combined production of gas reservoirs, which has the characteristics of simple structure, convenience and high efficiency.

[0006] Another object of the present invention is to provide an experimental method for simulating multi-layer combined production of gas reservoirs, which has the characteristic that the simulated environment is consistent with the actual development situation.

[0007] The technical solution adopted in the present invention is an experimental device for simulating multi-layer combined production of gas reservoirs, including a gas storage unit and a wellbore inserted into the gas storage unit. The gas storage unit is a hollow structure. One end of the wellbore extends into the gas storage unit to the bottom of the gas storage unit, and the other end of the wellbore is connected to an external gas source through a flow control valve. The flow control valve is connected to a gas flow meter and a pressure sensor. Multiple horizontal simulated gas storage layers are arranged in the gas storage unit.

[0008] The present invention is also characterized in that:

[0009] The wellbore includes an outer wellbore, the bottom of which extends to the bottom of the gas storage unit, and interlayer metal partition plates are horizontally fixed to the inner wall of the outer wellbore at the position corresponding to the intersection of each two adjacent simulated gas storage layers. A threaded hole is opened in the center of each interlayer metal partition plate, and the inner wellbore is threadedly connected to the threaded hole, and the inner wellbore is fixed by the threaded hole.

[0010] A plurality of pairs of fixed flow guide holes are symmetrically opened on the side wall of the outer wellbore. The outer wellbore fits tightly with the simulated gas storage layer and is connected with each gas storage layer through the fixed flow guide holes.

[0011] Sealing threads are arranged at the bottom of the outer wall of the inner wellbore and at positions corresponding to the threaded holes, and the sealing threads match the threaded holes.

[0012] Diversion holes are symmetrically opened on the side wall of the inner wellbore at positions corresponding to the simulated gas storage layers. The diversion holes are located between two adjacent sealing threads. The inner wellbore is detachable. By replacing the inner wellbore with different diversion holes, continuous or intermittent exploitation of single or multiple layers of each simulated gas storage layer can be achieved.

[0013] The gas storage unit is provided with a cover plate, a through hole is opened in the center of the cover plate, and the wellbore passes through the through hole.

[0014] Another technical solution adopted by the present invention is an experimental method for simulating multi-layer commingled production of gas reservoirs, using the above-mentioned experimental device for simulating multi-layer commingled production of gas reservoirs, and specifically implementing the following steps:

[0015] Step 1, selecting the core basic experimental materials required for each simulated gas reservoir, determining the mass of the core basic experimental materials required for each simulated gas reservoir according to the thickness of a single simulated gas reservoir, and weighing them;

[0016] Step 2: Lay the weighed core foundation experimental materials horizontally into the gas storage unit in sequence to obtain each simulated gas storage layer; open a diversion hole on the outer wall of the inner wellbore according to the preset mining demand and the position of the simulated gas storage layer to be mined, extend the inner wellbore into the bottom of the outer wellbore, tighten the threads, and put it into the gas storage unit until the outer wellbore contacts the bottom of the lowest simulated gas storage layer;

[0017] Step 3: Cover the gas storage unit with a cover plate with a through hole in the middle, and use a pressurizing device to pressurize the cover plate and the gas storage unit to press the core foundation experimental material in the gas storage unit into shape, and let it stand to solidify;

[0018] Step 4, casting epoxy resin on the outside of the gas storage unit formed by compression molding in step 3, and curing to obtain a simulated gas storage unit;

[0019] Step 5, placing the simulated gas storage unit in step 4 in a high-pressure container, applying a confining pressure to the simulated gas storage unit to the rated pressure of the high-pressure container, at which time the confining pressure of the simulated gas storage unit is the rated confining pressure;

[0020] Step 6: Connect a flow control valve at the top of the inner wellbore, connect the flow control valve to a flow meter, a pressure sensor and an external gas source, open the external gas source and the flow control valve, and fill the simulated gas storage unit with gas. When the pore pressure of the simulated gas storage unit monitored by the pressure sensor is 1-1.5 MPa less than the rated confining pressure, close the gas production flow control valve, remove the external gas source to stop filling, and record the cumulative gas injection volume Q1 through the gas flow meter;

[0021] Step 7, open the flow control valve and carry out multi-layer combined production according to the preset production requirements in step 2. When the gas flow meter monitors that the gas flow is less than 10mL / min, close the flow control valve, record the cumulative gas production Q2 through the gas flow meter and rotate out the inner wellbore to end the experiment.

[0022] Another technical solution of the present invention is also characterized in that:

[0023] In step 2, the standing time is 24 hours to 48 hours; in step 3, a cushion block is provided between the cover plate and the pressurizing device.

[0024] In step 5, the conducting medium of the high-pressure container is selected to be a liquid fluid with low compressibility.

[0025] In step 7, multi-layer combined production is specifically as follows: when the pore pressure drops to the experimental preset value of the current simulated gas reservoir, the inner wellbore is rotated outward until the diversion hole near the top of the inner wellbore is located in the next simulated gas reservoir, and the inner wellbore and the outer wellbore are tightened to develop the next layer of simulated gas reservoir to be mined; when the pore pressure drops to the experimental preset value of the simulated gas reservoir again, the inner wellbore is continued to be rotated outward until the diversion hole near the top of the inner wellbore is located in the next simulated gas reservoir, and the inner wellbore and the outer wellbore are tightened to develop the next layer of simulated gas reservoir to be mined, and this is repeated in sequence until the diversion hole near the top of the inner wellbore is located in the last simulated gas reservoir, and the inner wellbore and the outer wellbore are tightened to develop the last layer of simulated gas reservoir; when the gas flowmeter monitors a gas flow rate of less than 10mL / min, the flow control valve is closed, the cumulative gas production Q2 is recorded by the gas flowmeter, and the inner wellbore is rotated out to end the experiment.

[0026] The beneficial effects of the present invention are:

[0027] (1) The experimental device for simulating multi-layer commingled production of gas reservoirs of the present invention establishes gas flow channels of different reservoir combinations by changing the different rotation positions of the gas production wellbore. The gas transmission pipelines of each simulated gas reservoir are relatively independent, thereby simulating the multi-layer commingled production process of the gas reservoir and selectively developing each gas reservoir;

[0028] (2) The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention realizes the separation of layers by the engagement of the sealing threads of the inner gas production tube and the sealing threads of the metal partition plate between the layers of the outer gas production tube. The flow guide holes can be arranged corresponding to the position of the gas reservoir to be developed in each section of the inner gas production wellbore, so as to realize the continuous or intermittent production of single or multiple layers of gas reservoirs with multiple production layers, which is convenient and efficient.

[0029] (3) The experimental method of simulating multi-layer commingled production of gas reservoirs of the present invention can make each gas reservoir have a uniform pressure during implementation, which is consistent with the actual gas reservoir development situation;

[0030] (4) The experimental method of simulating multi-layer combined production of gas reservoirs of the present invention is to press and form multiple layers of diagenetic materials at one time and then encapsulate them into a whole with epoxy resin. Only one pressure vessel is needed to apply confining pressure, and there is no need to connect multiple core holders in parallel, which simplifies the experimental steps of multi-layer combined production of gas reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a multi-layer combined production device for simulating gas reservoirs according to the present invention;

[0032] Figure 2 It is a schematic diagram of the structure of the wellbore in the device of the present invention.

[0033] In the figure, 1. inner wellbore, 2. sealing thread, 3. outer wellbore, 4. guide hole, 5. interlayer metal partition plate, 6. threaded hole, 7. fixed guide hole, 8. flow control valve, 9. gas flow meter, 10. first simulated gas storage layer, 11. second simulated gas storage layer, 12. third simulated gas storage layer, 13 pressure sensor. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has a structure as follows: Figure 1 As shown, it includes a gas storage unit with a hollow structure, a plurality of horizontal simulated gas storage layers are arranged in the gas storage unit, a cover plate is arranged on the top of the gas storage unit, a through hole is opened in the center of the cover plate, a wellbore passes through the through hole, one end of the wellbore extends into the gas storage unit to the bottom of the gas storage unit, and the other end of the wellbore is connected to the external gas source through a flow control valve 8, the flow control valve 8 is connected to a gas flow meter 9 and a pressure sensor 13, the gas flow meter 9 is used to monitor the gas flow, and the pressure sensor 13 is used to monitor the pore pressure inside the gas storage unit, each simulated gas storage layer is pressed and formed at one time, and the seepage of gas between layers makes the pore pressure of each simulated gas storage layer uniform; the outside of the gas storage unit is cast and packaged with epoxy resin to make the confining pressure of each simulated gas storage layer uniform.

[0036] like Figure 2As shown, the wellbore includes an outer wellbore 3, the bottom of the outer wellbore 3 extends to the bottom of the gas storage unit, and the inner wall of the outer wellbore 3 and the position corresponding to the intersection of each two adjacent simulated gas storage layers are horizontally fixed with an interlayer metal partition plate 5, the edge of the interlayer metal partition plate 5 is tightly fitted with the inner wall of the outer wellbore 3, and the side wall of the outer wellbore 3 is symmetrically provided with a plurality of pairs of fixed guide holes 7, and is connected with the gas storage layer through the fixed guide holes 7. The outer wellbore 3 is in close contact with each simulated gas storage layer of the gas storage unit, so that the gas will not flow vertically on the contact surface between the outer wellbore 3 and each simulated gas storage layer; the center of the interlayer metal partition plate 5 is provided with a threaded hole 6, and the bottom of the outer wall of the inner wellbore 1 and the position corresponding to the threaded hole 6 are provided with a sealing thread 2, and the sealing thread 2 matches the threaded hole 6. The separation between the layers is achieved by the engagement of the sealing thread 2 and the threaded hole 6 of the interlayer metal partition plate 5, and the intersection between each simulated gas storage layer is ensured to be flush with the interlayer metal partition plate 5 by controlling the amount of diagenetic material required for a single gas layer.

[0037] The inner wellbore 1 has symmetrically provided flow guide holes 4 on its side wall, and the flow guide holes 4 are located between two adjacent sealing threads 2. The inner wellbore 1 is detachable, and the inner wellbore 1 with different flow guide holes 4 positions can be replaced to achieve continuous or intermittent exploitation of single or multiple layers of each simulated gas reservoir. The flow guide holes 4 are arranged in accordance with development needs, and the positions of the flow guide holes 4 correspond to the positions of the simulated gas reservoirs to be exploited. By setting the flow guide holes 4 at different positions on the inner wellbore 1, the production pressure difference of each gas reservoir can be controlled, and continuous or intermittent exploitation of single or multiple layers of each simulated gas reservoir can be achieved, thereby simulating multi-layer combined exploitation of gas layers.

[0038] The experimental method for simulating multi-layer commingled production of a gas reservoir adopts the experimental device for simulating multi-layer commingled production of a gas reservoir, and is specifically implemented in the following steps:

[0039] Step 1, selecting the core basic experimental materials required for each simulated gas reservoir, determining the mass of the core basic experimental materials required for each simulated gas reservoir according to the thickness of a single simulated gas reservoir, and weighing them;

[0040] Step 2: Lay the weighed core foundation experimental materials horizontally into the gas storage unit in sequence to obtain each simulated gas storage layer; according to the preset mining requirements and the position of the simulated gas storage layer to be mined, open the guide hole 4 on the side wall of the inner wellbore 1, extend the inner wellbore 1 into the bottom of the outer wellbore 3, tighten the threads, and put it into the gas storage unit until the outer wellbore 3 contacts the bottom of the lowest simulated gas storage layer;

[0041] The inner wellbore 1 is removable and replaceable, and a guide hole 4 can be opened on the outer wall of the inner wellbore 1 according to the mining needs. Single-layer mining or multi-layer sequential mining or interval mining can be achieved by replacing the inner wellbore 1 with different guide hole positions. In single-layer mining, only the guide hole 4 is opened at the position corresponding to the bottom of the outer wall of the inner wellbore 1 and the bottom layer of the simulated gas storage layer; in multi-layer sequential mining or multi-layer interval mining, the guide hole 4 is opened at the position corresponding to the outer wall of the inner wellbore 1 and the simulated gas storage layer to be mined according to the mining method.

[0042] Step 3: Cover the gas storage unit with a cover plate with a through hole in the middle, place cushion blocks on the four corners of the cover plate, use a pressurizing device or a hydraulic device to pressurize the cover plate and the gas storage unit, increase the pressure of the hydraulic press, and transmit the pressure to the cover plate by squeezing the cushion blocks, so that the core foundation experimental material in the gas storage unit is pressed into shape and left to stand for 24 hours to 48 hours to solidify;

[0043] The cover plate with a through hole in the middle allows the surplus parts of the inner wellbore 1 and the outer wellbore 3 to pass through the through hole, thereby preventing the wellbore from being deformed by force during the compaction process; the pads placed at the four corners can leave the middle position empty to prevent the inner wellbore 1 and the outer wellbore 3 from directly contacting the hydraulic device and causing vertical deformation; the hydraulic device or the pressurizing device is used to press and form the gas storage unit;

[0044] Step 4, casting epoxy resin on the outside of the gas storage unit formed by compression molding in step 3, placing it in a cool and dry place until the epoxy resin is completely cured, and obtaining a simulated gas storage unit;

[0045] The gas storage unit is made into a sealed whole by casting epoxy resin, so as to ensure that the confining pressure of each simulated gas storage layer is the same, and each simulated gas storage layer maintains a uniform pore pressure through gas seepage between layers;

[0046] Step 5, placing the simulated gas storage unit in step 4 in a high-pressure container, applying a confining pressure to the simulated gas storage unit to the rated pressure of the high-pressure container, at which time the confining pressure of the simulated gas storage unit is the rated confining pressure;

[0047] The pressure transmission medium of the high-pressure container is generally a liquid fluid with low compressibility; the high-pressure container is used to apply confining pressure to the gas storage unit;

[0048] Step 6: Connect the flow control valve 8 to the top of the inner wellbore 1, connect the flow control valve 8 to the gas flow meter 9, the pressure sensor 13 and the external gas source, open the external gas source and the flow control valve 8, and fill the simulated gas storage unit with gas. When the pore pressure monitored by the pressure sensor 13 is 1-1.5 MPa less than the rated confining pressure, close the gas production flow control valve, remove the external gas source to stop filling, and record the cumulative gas injection volume Q1 through the gas flow meter 9;

[0049] Step 7, open the flow control valve 8, and carry out multi-layer combined production according to the preset production requirements in step 2. When the gas flow rate monitored by the gas flow meter 9 is less than 10mL / min, close the flow control valve 8, record the cumulative gas production Q2 through the gas flow meter 9, and rotate out the inner wellbore 1 to end the experiment.

[0050] In step 7, multi-layer combined production is specifically as follows: when the pore pressure drops to the experimental preset value of the current simulated gas reservoir, the inner wellbore 1 is rotated outward until the guide hole 4 near the top of the inner wellbore 1 is located in the next simulated gas reservoir, and then the inner wellbore 1 and the outer wellbore 3 are tightened to develop the next simulated gas reservoir to be mined; when the pore pressure drops to the experimental preset value of the simulated gas reservoir again, the inner wellbore 1 is continued to be rotated outward until the guide hole 4 near the top of the inner wellbore 1 is located in the next simulated gas reservoir, and then the inner wellbore 1 and the outer wellbore 3 are tightened to develop the next simulated gas reservoir to be mined, and this is repeated in sequence until the guide hole 4 near the top of the inner wellbore 1 is located in the last simulated gas reservoir, and then the inner wellbore 1 and the outer wellbore 3 are tightened to develop the last simulated gas reservoir; when the gas flowmeter 9 monitors that the gas flow rate is less than 10mL / min, the flow control valve 8 is closed, the cumulative gas production Q2 is recorded by the gas flowmeter 9, and the inner wellbore 1 is rotated out to end the experiment.

[0051] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has the following working principle: epoxy resin is cast on the gas storage layer to make the confining pressure of each simulated gas storage layer uniform; under the same confining pressure condition, different gas storage layer-gas production inner wellbore seepage channels are constructed by adjusting the position of the inner wellbore with guide holes at different positions, and then the production experiment is carried out after the gas storage layer is inflated.

[0052] The experimental device and method for simulating multi-layer combined production of gas reservoirs of the present invention have the following advantages: relatively independent gas transmission pipelines can be established for each simulated gas storage layer, and each gas storage layer of the gas reservoir can be selectively developed; during the implementation process, each gas storage layer can have a unified pressure system, which is consistent with the actual gas reservoir development situation; the multi-layer diagenetic material is pressed and formed at one time and then packaged into a whole with epoxy resin, only one pressure vessel is needed to apply confining pressure, and there is no need to connect multiple core clamps in parallel, which simplifies the experimental steps of multi-layer combined production of gas reservoirs.

[0053] Example 1

[0054] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has a structure as follows: Figure 1As shown, it includes a gas storage unit with a hollow structure, the gas storage unit is provided with a cover plate, a through hole is opened in the center of the cover plate, an outer wellbore 3 passes through the through hole and one end extends into the gas storage unit to the bottom of the gas storage unit, the top of the inner wellbore 1 is connected to the external gas source through a flow control valve 8, the flow control valve 8 is connected to a gas flow meter 9 and a pressure sensor 13, three horizontal simulated gas storage layers are arranged in the gas storage unit, namely a first simulated gas storage layer 10, a second simulated gas storage layer 11, and a third simulated gas storage layer 12, each simulated gas storage layer is pressed and formed at one time, and the seepage of gas between layers makes the pore pressure of each simulated gas storage layer uniform; the outside of the gas storage unit is cast and packaged with epoxy resin to make the confining pressure of each simulated gas storage layer uniform.

[0055] Interlayer metal partition plates 5 are horizontally fixed at positions corresponding to the intersections between the inner wall of the outer wellbore 3 and each adjacent simulated gas storage layers. Threaded holes 6 are provided at the centers of the interlayer metal partition plates 5. Sealing threads 2 are provided on the outer wall of the inner wellbore 1. The sealing threads 2 match the threaded holes 6. The separation between the layers is achieved by the engagement of the sealing threads 2 and the threaded holes 6 of the interlayer metal partition plates. The intersections between the simulated gas storage layers are flush with the interlayer metal partition plates 5 by controlling the amount of diagenetic materials required for a single gas layer. The edges of the interlayer metal partition plates 5 are tightly fitted to the inner wall of the outer wellbore 3. Six pairs of fixed guide holes 7 are symmetrically provided on the side walls of the outer wellbore 3. Two pairs of fixed guide holes 7 correspond to each gas storage layer, and the gas storage layers are connected through the fixed guide holes 7. The outer wellbore 3 is in close contact with the simulated gas storage layers of the gas storage unit, so that the gas will not flow vertically on the contact surface between the outer wellbore 3 and the simulated gas storage layers.

[0056] Two pairs of guide holes 4 are respectively opened at positions corresponding to the second simulated gas storage layer 11 and the third simulated gas storage layer 12 on the side wall of the inner wellbore 1, and two layers are mined simultaneously each time, sequentially from bottom to top.

[0057] Example 2

[0058] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has a structure as follows: Figure 1 As shown, it includes a gas storage unit with a hollow structure, the gas storage unit is provided with a cover plate, a through hole is opened in the center of the cover plate, an outer wellbore 3 passes through the through hole and one end extends into the gas storage unit to the bottom of the gas storage unit, the top of the inner wellbore 1 is connected to the external gas source through a flow control valve 8, the flow control valve 8 is connected to a gas flow meter 9 and a pressure sensor 13, three horizontal simulated gas storage layers are arranged in the gas storage unit, namely a first simulated gas storage layer 10, a second simulated gas storage layer 11, and a third simulated gas storage layer 12, each simulated gas storage layer is pressed and formed at one time, and the seepage of gas between layers makes the pore pressure of each simulated gas storage layer uniform; the outside of the gas storage unit is cast and packaged with epoxy resin to make the confining pressure of each simulated gas storage layer uniform.

[0059] Interlayer metal partition plates 5 are horizontally fixed at positions corresponding to the intersections between the inner wall of the outer wellbore 3 and each adjacent simulated gas storage layers. Threaded holes 6 are provided at the centers of the interlayer metal partition plates 5. Sealing threads 2 are provided on the outer wall of the inner wellbore 1. The sealing threads 2 match the threaded holes 6. The separation between the layers is achieved by the engagement of the sealing threads 2 and the threaded holes 6 of the interlayer metal partition plates. The intersections between the simulated gas storage layers are flush with the interlayer metal partition plates 5 by controlling the amount of diagenetic materials required for a single gas layer. The edges of the interlayer metal partition plates 5 are tightly fitted to the inner wall of the outer wellbore 3. Six pairs of fixed guide holes 7 are symmetrically provided on the side walls of the outer wellbore 3. Two pairs of fixed guide holes 7 correspond to each gas storage layer, and the gas storage layers are connected through the fixed guide holes 7. The outer wellbore 3 is in close contact with the simulated gas storage layers of the gas storage unit, so that the gas will not flow vertically on the contact surface between the outer wellbore 3 and the simulated gas storage layers.

[0060] Two pairs of diversion holes 4 are respectively opened at positions on the side wall of the inner wellbore 1 corresponding to the first simulated gas storage layer 10, the second simulated gas storage layer 11 and the third simulated gas storage layer 12, so that the three layers can be produced simultaneously.

[0061] Example 3

[0062] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has a structure as follows: Figure 1 As shown, it includes a gas storage unit with a hollow structure, one end of the outer wellbore 3 extends into the gas storage unit to the bottom of the gas storage unit, the top of the inner wellbore 1 is connected to the external gas source through the flow control valve 8, the flow control valve 8 is connected to the gas flow meter 9 and the pressure sensor 13, and four horizontal simulated gas storage layers are arranged in the gas storage unit, namely the first simulated gas storage layer 10, the second simulated gas storage layer 11, the third simulated gas storage layer 12, and the fourth simulated gas storage layer, each simulated gas storage layer is pressed and formed at one time, and the seepage of gas between layers makes the pore pressure of each simulated gas storage layer uniform; the outside of the gas storage unit is cast and packaged with epoxy resin to make the confining pressure of each simulated gas storage layer uniform.

[0063] Interlayer metal partition plates 5 are horizontally fixed at positions corresponding to the intersections of the inner wall of the outer wellbore 3 and each adjacent simulated gas storage layers. Threaded holes 6 are provided in the centers of the interlayer metal partition plates 5. Sealing threads 2 are provided on the outer wall of the inner wellbore 1. The sealing threads 2 match the threaded holes 6. The separation between the layers is achieved by the engagement of the sealing threads 2 and the threaded holes 6 of the interlayer metal partition plates. The intersections between the simulated gas storage layers are flush with the interlayer metal partition plates 5 by controlling the amount of diagenetic materials required for a single gas layer. The edges of the interlayer metal partition plates 5 are tightly fitted to the inner wall of the outer wellbore 3. Eight pairs of fixed guide holes 7 are symmetrically provided on the side walls of the outer wellbore 3. Two pairs of fixed guide holes 7 correspond to each gas storage layer, and the gas storage layers are connected through the fixed guide holes 7. The outer wellbore 3 is in close contact with the simulated gas storage layers of the gas storage unit, so that the gas will not flow vertically on the contact surface between the outer wellbore 3 and the simulated gas storage layers.

[0064] Two pairs of guide holes 4 are respectively opened at positions corresponding to the second simulated gas storage layer 11 and the fourth simulated gas storage layer on the side wall of the inner wellbore 1, and two layers are mined at the same time, sequentially from bottom to top.

[0065] Example 4

[0066] The experimental device for simulating multi-layer combined production of gas reservoirs of the present invention has a structure as follows: Figure 1 As shown, it includes a gas storage unit with a hollow structure, one end of the outer wellbore 3 extends into the gas storage unit to the bottom of the gas storage unit, the top of the inner wellbore 1 is connected to the external gas source through the flow control valve 8, the flow control valve 8 is connected to the gas flow meter 9 and the pressure sensor 13, and three horizontal simulated gas storage layers are arranged in the gas storage unit, namely the first simulated gas storage layer 10, the second simulated gas storage layer 11 and the third simulated gas storage layer 12. Each simulated gas storage layer is pressed and formed at one time, and the seepage of gas between the layers makes the pore pressure of each simulated gas storage layer uniform; the outside of the gas storage unit is cast and packaged with epoxy resin to make the confining pressure of each simulated gas storage layer uniform.

[0067] Interlayer metal partition plates 5 are horizontally fixed at positions corresponding to the intersections between the inner wall of the outer wellbore 3 and each adjacent simulated gas storage layers. Threaded holes 6 are provided at the centers of the interlayer metal partition plates 5. Sealing threads 2 are provided on the outer wall of the inner wellbore 1. The sealing threads 2 match the threaded holes 6. The separation between the layers is achieved by the engagement of the sealing threads 2 and the threaded holes 6 of the interlayer metal partition plates. The intersections between the simulated gas storage layers are flush with the interlayer metal partition plates 5 by controlling the amount of diagenetic materials required for a single gas layer. The edges of the interlayer metal partition plates 5 are tightly fitted to the inner wall of the outer wellbore 3. Six pairs of fixed guide holes 7 are symmetrically provided on the side walls of the outer wellbore 3. Two pairs of fixed guide holes 7 correspond to each gas storage layer, and the gas storage layers are connected through the fixed guide holes 7. The outer wellbore 3 is in close contact with the simulated gas storage layers of the gas storage unit, so that the gas will not flow vertically on the contact surface between the outer wellbore 3 and the simulated gas storage layers.

[0068] A pair of diversion holes 4 are symmetrically opened at the positions of the side wall of the inner wellbore 1 corresponding to the first simulated gas storage layer 10, and two pairs of diversion holes 4 are symmetrically opened at the positions of the side wall of the inner wellbore 1 corresponding to the third simulated gas storage layer 12. Only the first simulated gas storage layer 10 and the third simulated gas storage layer 12 are exploited at the same time.

[0069] Example 5

[0070] The experimental method for simulating multi-layer commingled production of gas reservoirs of the present invention adopts the experimental device of Example 1 of the present invention and is specifically implemented according to the following steps:

[0071] Step 1: According to the porosity of each layer in Table 1 below and permeability K i It is required to prepare three kinds of artificial core basic experimental materials;

[0072] Table 1 Porosity and permeability requirements for each simulated layer

[0073]

[0074] The mass of core basic experimental materials required for each simulated gas reservoir is determined according to the thickness of each simulated gas reservoir, and three kinds of diagenetic materials are weighed respectively;

[0075] Step 2, adding core basic experimental materials in sequence according to the spatial order of the actual reservoir, first pouring the third layer of artificial core basic material into the bottom of the gas storage unit and flattening it, then adding the second layer of artificial core basic experimental material, and finally adding the first layer of artificial core basic experimental material to obtain each simulated gas storage layer; the preset mining requirement is to mine two layers at the same time each time, and to mine sequentially from bottom to top, and two pairs of guide holes 4 are respectively opened at the positions corresponding to the second simulated gas storage layer 11 and the third simulated gas storage layer 12 on the side wall of the inner wellbore 1, and the inner wellbore 1 is extended into the bottom thread of the outer wellbore 3 and tightened, and then placed in the gas storage unit until the outer wellbore 3 contacts the bottom simulated gas storage layer;

[0076] Step 3: Cover the gas storage unit with a cover plate with a through hole in the middle, place 4 pads at the four corners of the cover plate, use a hydraulic device to pressurize the cover plate pads and the gas storage unit, so that the core foundation experimental material in the gas storage unit is pressed into shape, and then left to stand for 24 hours to solidify;

[0077] Step 4, casting epoxy resin on the outside of the gas storage unit formed by compression molding in step 3 to form a packaging layer of about 0.5 to 2.0 cm on its surface; placing it in a cool and dry place until the epoxy resin is completely cured to obtain a simulated gas storage unit;

[0078] Step 5, placing the simulated gas storage unit in step 4 in a pressure cabin, applying a confining pressure to the simulated gas storage unit to a rated pressure of 10 MPa of the pressure cabin, and selecting water as the pressure transmission medium. At this time, the confining pressure of the simulated gas storage unit is the rated confining pressure;

[0079] Step 6: Connect the flow control valve 8 to the top of the inner wellbore 1, connect the flow control valve 8 to the gas flow meter 9, the pressure sensor 13 and the external gas source, open the external gas source and the flow control valve 8, fill the simulated gas storage unit with gas, and stop when the pore pressure monitored by the pressure sensor 13 rises to 9MPa, close the gas production flow control valve 8, remove the external gas source to stop filling, and record the cumulative gas injection volume Q1 as 203L through the gas flow meter 9;

[0080] Step 7, open the flow control valve 8, at this time the second simulated gas storage layer 11 and the third simulated gas storage layer 12, when the pore pressure drops to the experimental preset value of 6MPa, unscrew the inner wellbore 1 until the guide hole 4 near the top of the inner wellbore 1 is located in the first simulated gas storage layer 10, tighten the inner wellbore 1 and the outer wellbore 3, at this time the first simulated gas storage layer 10 and the second simulated gas storage layer 11 are developed simultaneously, when the gas flow meter 9 monitors the gas flow rate is less than 10mL / min, close the flow control valve 8, record the cumulative gas production Q2 as 193L through the gas flow meter 9 and unscrew the inner wellbore 1 to end the experiment.

[0081] Example 6

[0082] The experimental method for simulating multi-layer commingled production of gas reservoirs of the present invention adopts the experimental device of Example 4 of the present invention and is specifically implemented according to the following steps:

[0083] Steps 1-2 are the same as those in Example 5. In step 3, the mixture is allowed to stand for 48 hours for solidification. The rest is the same as in Example 5. Steps 4-6 are the same as in Example 5. The cumulative gas injection volume Q1 is recorded as 203 L.

[0084] Step 7, open the flow control valve 8, and develop the first and third simulated gas storage layers at the same time. When the flow rate of the gas flow meter 9 is less than 10mL / min, the cumulative gas production is recorded as 189L, and the experiment is ended.

Claims

1. An experimental device for simulating multi-layer combined production of gas reservoirs, characterized in that: The invention comprises a gas storage unit and a wellbore inserted into the gas storage unit, wherein the gas storage unit is a hollow structure, one end of the wellbore extends into the gas storage unit to the bottom of the gas storage unit, and the other end of the wellbore is connected to an external gas source via a flow control valve (8), wherein the flow control valve (8) is connected to a gas flow meter (9) and a pressure sensor (13), and a plurality of transverse simulated gas storage layers are arranged in the gas storage unit.

2. The experimental device for simulating multi-layer commingled production of gas reservoirs according to claim 1 is characterized in that: The wellbore comprises an outer wellbore (3), the bottom of the outer wellbore (3) extends to the bottom of the gas storage unit, and an interlayer metal partition plate (5) is horizontally fixedly connected to the inner wall of the outer wellbore (3) at a position corresponding to the intersection of each two adjacent simulated gas storage layers, and a threaded hole (6) is opened at the center of each interlayer metal partition plate (5), and the inner wellbore (1) is connected to the inner thread of the threaded hole (6), and the inner wellbore (1) is fixed by the threaded hole (6).

3. The experimental device for simulating multi-layer commingled production of gas reservoirs according to claim 2, characterized in that: The side wall of the outer wellbore (3) is symmetrically provided with a plurality of pairs of fixed flow guide holes (7); the outer wellbore (3) is tightly fitted to the simulated gas storage layer and is connected to each of the gas storage layers through the fixed flow guide holes (7).

4. The experimental device for simulating multi-layer commingled production of gas reservoirs according to claim 2, characterized in that: Sealing threads (2) are provided at the bottom of the outer wall of the inner wellbore (1) and at a position corresponding to the threaded hole (6), and the sealing threads (2) match the threaded hole (6).

5. The experimental device for simulating multi-layer commingled production of gas reservoirs according to claim 4, characterized in that: The inner wellbore (1) has flow guide holes (4) symmetrically opened at positions corresponding to the simulated gas storage layers on the side wall, and the flow guide holes (4) are located between two adjacent sealing threads (2). The inner wellbore (1) is detachable, and continuous or intermittent exploitation of single or multiple layers of each simulated gas storage layer can be achieved by replacing the inner wellbore (1) with a different position of the flow guide holes (4).

6. The experimental device for simulating multi-layer commingled production of gas reservoirs according to any one of claims 1 to 5, characterized in that: The gas storage unit is provided with a cover plate, a through hole is opened at the center of the cover plate, and the wellbore passes through the through hole.

7. An experimental method for simulating multi-layer commingled production of gas reservoirs, characterized in that: The experimental device for simulating multi-layer commingled production of gas reservoirs as described in claims 1 to 6 is specifically implemented in the following steps: Step 1, selecting the core basic experimental materials required for each simulated gas reservoir, determining the mass of the core basic experimental materials required for each simulated gas reservoir according to the thickness of a single simulated gas reservoir, and weighing them; Step 2, the weighed core foundation experimental materials are laid horizontally in the gas storage unit in sequence to obtain each simulated gas storage layer; according to the preset mining requirements and the position of the simulated gas storage layer to be mined, the guide hole (4) is correspondingly opened on the outer wall of the inner wellbore (1), the inner wellbore (1) is extended into the bottom thread of the outer wellbore (3) and tightened, and then placed in the gas storage unit until the outer wellbore (3) contacts the bottom of the simulated gas storage layer at the bottom; Step 3: Cover the gas storage unit with a cover plate with a through hole in the middle, and use a pressurizing device to pressurize the cover plate and the gas storage unit to press the core foundation experimental material in the gas storage unit into shape, and let it stand to solidify; Step 4, casting epoxy resin on the outside of the gas storage unit formed by compression molding in step 3, and curing to obtain a simulated gas storage unit; Step 5, placing the simulated gas storage unit in step 4 in a high-pressure container, applying a confining pressure to the simulated gas storage unit to the rated pressure of the high-pressure container, at which time the confining pressure of the simulated gas storage unit is the rated confining pressure; Step 6: Connect a flow control valve (8) at the top of the inner wellbore (1), connect the flow control valve (8) to a flow meter (9), a pressure sensor (13) and an external gas source, open the external gas source and the flow control valve (8), and fill the simulated gas storage unit with gas. When the pore pressure of the simulated gas storage unit monitored by the pressure sensor (13) is 1 to 1.5 MPa less than the rated confining pressure, close the gas production flow control valve (8), remove the external gas source to stop filling, and record the cumulative gas injection volume Q1 through the gas flow meter (9); Step 7, open the flow control valve (8), and carry out multi-layer combined production according to the preset production requirements in step 2. When the gas flow rate monitored by the gas flow meter (9) is less than 10mL / min, close the flow control valve (8), record the cumulative gas production Q2 through the gas flow meter (9), and rotate out the inner wellbore (1), ending the experiment.

8. The experimental method for simulating multi-layer commingled production of gas reservoirs according to claim 7, characterized in that: In step 2, the standing time is 24 to 48 hours; in step 3, a cushion block is provided between the cover plate and the pressurizing device.

9. The experimental method for simulating multi-layer commingled production of gas reservoirs according to claim 7, characterized in that: In step 5, the conducting medium of the high-pressure container is selected to be a liquid fluid with low compressibility.

10. The experimental method for simulating multi-layer commingled production of gas reservoirs according to claim 7, characterized in that: In step 7, the multi-layer combined production is specifically as follows: when the pore pressure drops to the experimental preset value of the current simulated gas reservoir, the inner wellbore (1) is rotated outward until the diversion hole (4) near the top of the inner wellbore (1) is located in the next simulated gas reservoir, and the inner wellbore (1) and the outer wellbore (3) are tightened to develop the next simulated gas reservoir to be mined. When the pore pressure drops to the experimental preset value of the simulated gas reservoir again, the inner wellbore (1) is continued to be rotated outward until the diversion hole (4) near the top of the inner wellbore (1) is located in the next simulated gas reservoir. , tighten the inner wellbore (1) and the outer wellbore (3), and develop the next layer of simulated gas reservoir to be mined, and repeat in sequence until the guide hole (4) near the top of the inner wellbore (1) is located in the last layer of simulated gas reservoir, tighten the inner wellbore (1) and the outer wellbore (3), and develop the last layer of simulated gas reservoir. When the gas flow rate monitored by the gas flow meter (9) is less than 10mL / min, close the flow control valve (8), record the cumulative gas production Q2 through the gas flow meter (9), and unscrew the inner wellbore (1), ending the experiment.

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