Experimental device and experimental method for simulating multi-layer combined production of gas reservoirs

Abstract

The experimental device for simulating multi-layer combined production of gas reservoirs comprises 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 until the bottom of the gas storage unit, the other end of the wellbore 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 multiple transverse simulated gas storage layers are arranged in the gas storage unit; the experimental device and the experimental method for simulating multi-layer combined production of gas reservoirs, by changing the different rotating positions of the gas wellbore, the gas flow channels of different reservoir combinations are established, the gas transmission pipelines of the simulated gas storage layers are relatively independent, thereby the multi-layer combined production process of the gas reservoir is simulated, each gas storage layer of the gas reservoir is selectively developed, and in the implementation process, each gas storage layer can have a unified pressure which is consistent with the actual gas reservoir development situation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas reservoir recovery, and relates to an experimental device for simulating multi-layer commingled production of a gas reservoir and an experimental method for simulating multi-layer commingled production of a gas reservoir. BACKGROUND

[0002] Generally, there are multiple reservoirs in an oil and gas reservoir, and in the whole development process, in order to improve the producing degree of reserves and realize economic and efficient development, a multi-layer commingled production mode is adopted.

[0003] Multi-layer commingled production of a gas reservoir is also one of the means for effectively controlling the water invasion profile. On the one hand, it can increase the production pressure difference of a low-permeability layer, improve the fluid flow speed of the low-permeability layer, and make the liquid production profile of the low-permeability layer advance faster; on the other hand, it can reduce the production pressure difference of a high-permeability layer, slow down the advance speed of the liquid production profile of the high-permeability layer, and finally make the liquid production profile of the high-permeability layer level with that of the low-permeability layer, thereby minimizing the adverse effects of water invasion of a gas reservoir on recovery, and thus an experimental device and method are urgently needed to simulate the multi-layer commingled production process of a gas reservoir.

[0004] At present, there are many studies on physical simulation of the water invasion process of a water-bearing gas reservoir, for example, a plurality of core holders are connected in parallel or in series to study the water invasion dynamics, but this does not match the actual situation that all the gas-producing layers have a unified pressure during the development of a gas reservoir, which to some extent reduces the guiding effect of the experimental results on production practice. Few scholars have in-depth explored the device and method for multi-layer commingled production in the simulation development process of a gas reservoir. SUMMARY

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

[0006] Another purpose of the present application is to provide an experimental method for simulating multi-layer commingled production of a gas reservoir, which has the characteristic that the simulated environment matches the actual development situation.

[0007] The technical solution adopted by the present application is that the experimental device for simulating multi-layer commingled production of a gas reservoir comprises 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 until the bottom of the gas storage unit, the other end of the wellbore is connected 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 simulated gas storage layers are arranged in the gas storage unit.

[0008] The present application also has the following characteristics:

[0009] The well shaft comprises an outer well shaft, the bottom of the outer well shaft extends to the bottom of the gas storage unit, an interlayer metal partition plate is horizontally fixed at a position corresponding to the intersection of each adjacent two simulated gas storage layers on the inner wall of the outer well shaft, a threaded hole is formed in the center of each interlayer metal partition plate, and an inner well shaft is threadedly connected in the threaded hole and fixed through the threaded hole.

[0010] A plurality of pairs of fixed flow guide holes are symmetrically formed in the side wall of the outer well shaft, the outer well shaft is tightly attached to the simulated gas storage layers, and the outer well shaft is in communication 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 well shaft and positions corresponding to the threaded holes, and the sealing threads are matched with the threaded holes.

[0012] Flow guide holes are symmetrically formed in the side wall of the inner well shaft at positions corresponding to the simulated gas storage layers, the flow guide holes are located between adjacent two sealing threads, the inner well shaft is detachable, and continuous or interval mining of each simulated gas storage layer in single layer or multiple layers is realized by replacing the inner well shaft with different flow guide hole positions.

[0013] The gas storage unit is provided with a cover plate, a through hole is formed in the center of the cover plate, and the well shaft penetrates through the through hole.

[0014] Another technical solution adopted by the present application is an experimental method for simulating multi-layer combined mining of gas reservoirs, which uses the above-mentioned experimental device for simulating multi-layer combined mining of gas reservoirs, and is specifically implemented according to the following steps

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

[0016] Step 2, sequentially horizontally laying the weighed core basic experimental materials into the gas storage unit to obtain each simulated gas storage layer; according to the preset mining requirement and the position of the simulated gas storage layer to be mined, a flow guide hole is formed in the outer wall of the inner well shaft, the inner well shaft is inserted into the outer well shaft, and after being screwed tightly, it is placed into the gas storage unit until the outer well shaft contacts the bottom of the bottommost simulated gas storage layer;

[0017] Step 3, covering the cover plate with a through hole in the middle of the gas storage unit, using a pressurizing device to pressurize the cover plate and the gas storage unit, and pressing and forming the core basic experimental materials in the gas storage unit, and then standing for solidification;

[0018] Step 4, casting epoxy resin outside the gas storage unit after the pressing and forming in step 3, and solidifying to obtain a simulated gas storage unit;

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

[0020] Step 6, connecting a flow control valve at the top of the inner wellbore, connecting the flow control valve with a flow meter, a pressure sensor and an external gas source, opening the external gas source and the flow control valve, filling the simulated gas storage unit with gas, when the pressure sensor monitors that the simulated gas storage unit pore pressure is 1-1.5 MPa less than the rated confining pressure, closing the gas production flow control valve, removing the external gas source to stop filling, and recording the cumulative gas injection amount Q1 through the gas flow meter;

[0021] Step 7, opening the flow control valve, multi-layer commingling production according to the pre-set production requirement in step 2, when the gas flow meter monitors that the gas flow is less than 10 mL / min, closing the flow control valve, recording the cumulative gas production amount Q2 through the gas flow meter and rotating out the inner wellbore, ending the experiment.

[0022] The technical scheme of another aspect of the present application is characterized in that:

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

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

[0025] In step 7, the multi-layer commingling production is specifically as follows: when the pore pressure drops to the experimental pre-set value of the current simulated gas layer, rotating out the inner wellbore to the position where the flow guide hole of the inner wellbore close to the top is located in the next simulated gas layer, rotating the inner wellbore and the outer wellbore tightly, developing the next simulated gas layer to be produced, when the pore pressure drops again to the experimental pre-set value of the simulated gas layer, continuing to rotate out the inner wellbore to the position where the flow guide hole of the inner wellbore close to the top is located in the next simulated gas layer, rotating the inner wellbore and the outer wellbore tightly, developing the next simulated gas layer to be produced, and repeating in turn until the flow guide hole of the inner wellbore close to the top is located in the last simulated gas layer, rotating the inner wellbore and the outer wellbore tightly, developing the last simulated gas layer, when the gas flow meter monitors that the gas flow is less than 10 mL / min, closing the flow control valve, recording the cumulative gas production amount Q2 through the gas flow meter and rotating out the inner wellbore, ending the experiment.

[0026] The present application has the following beneficial effects:

[0027] (1) The experimental device for simulating multi-layer commingling production of gas reservoirs of the present application can establish gas flow channels of different reservoir combinations by changing the rotating-in position of the gas production wellbore, the gas transmission pipelines of each simulated gas layer are relatively independent, thereby simulating the multi-layer commingling production process of gas reservoirs and selectively developing each gas reservoir of the gas reservoirs;

[0028] (2) the experimental device for simulating multi-layer combined production of gas reservoirs of the present application realizes the separation of gas production among layers by the engagement of the sealing threads of the gas production inner cylinder and the interlayer metal separation plates of the gas production outer cylinder, the flow guide holes are arranged on each section of the inner well cylinder according to the position of the gas storage layer to be developed, and the continuous or interval production of single layer or multiple layers of the multiple production layer gas reservoirs is realized, which is convenient and efficient;

[0029] (3) the experimental method for simulating multi-layer combined production of gas reservoirs of the present application can make each gas storage layer have a unified pressure in the implementation process, which is consistent with the actual gas reservoir development situation;

[0030] (4) the experimental method for simulating multi-layer combined production of gas reservoirs of the present application presses and forms the multiple layers of rock materials at one time, then encapsulates them as a whole by using epoxy resin, and only needs to apply confining pressure by using one pressure container, without the need of connecting multiple core holders in parallel, which simplifies the experimental steps of multi-layer combined production of gas reservoirs. BRIEF DESCRIPTION OF DRAWINGS

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

[0032] Figure 2 is a structural schematic diagram of the well cylinder in the device of the present application.

[0033] In the figure, 1. inner well cylinder, 2. sealing thread, 3. outer well cylinder, 4. flow guide hole, 5. interlayer metal separation plate, 6. threaded hole, 7. fixed flow 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 application will be described in detail below in combination with the drawings and specific embodiments.

[0035] The experimental device for simulating multi-layer combined production of gas reservoirs of the present application has the structure as shown in Figure 1 The device includes a gas storage unit with a hollow structure, multiple transverse simulated gas storage layers are arranged in the gas storage unit, a cover plate is arranged at the top of the gas storage unit, a through hole is formed in the center of the cover plate, a well cylinder passes through the through hole, one end of the well cylinder extends into the gas storage unit until the bottom of the gas storage unit, the other end of the well cylinder is connected with an external gas source through a flow control valve 8, the flow control valve 8 is connected with 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 among layers makes the pore pressures of each simulated gas storage layer uniform; the gas storage unit is encapsulated by casting with epoxy resin, so that the confining pressure borne by each simulated gas storage layer is uniform.

[0036] As shown in Figure 2As shown, the wellbore comprises an outer wellbore 3, the bottom of the outer wellbore 3 extends to the bottom of the gas storage unit, the inner wall of the outer wellbore 3 is horizontally fixed at a position corresponding to the intersection of each adjacent two simulated gas reservoirs, and an interlayer metal partition plate 5 is fixed at the edge of the interlayer metal partition plate 5 and the inner wall of the outer wellbore 3. The outer wellbore 3 is symmetrically provided with a plurality of pairs of fixed flow guide holes 7 on the side wall, and is in communication with the gas reservoir through the fixed flow guide holes 7. The outer wellbore 3 is in close contact with each simulated gas reservoir 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 reservoir; a threaded hole 6 is formed in the center of the interlayer metal partition plate 5, a sealing thread 2 is arranged at the bottom of the outer wall of the inner wellbore 1 and a position corresponding to the threaded hole 6, and the sealing thread 2 is matched with the threaded hole 6. The separation between layers is realized 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 reservoir 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] A flow guide hole 4 is symmetrically formed on the side wall of the inner wellbore 1, the flow guide hole 4 is located between two adjacent sealing threads 2, the inner wellbore 1 is detachable, and the continuous or interval mining of each simulated gas reservoir single layer or multiple layers is realized by replacing the inner wellbore 1 with different positions of the flow guide hole 4. The flow guide hole 4 is arranged according to the development requirements, the position of the flow guide hole 4 corresponds to the position of the simulated gas reservoir to be mined, and the production pressure difference of each gas reservoir is controlled by arranging the flow guide hole 4 at different positions on the inner wellbore 1, so as to realize the continuous or interval mining of each simulated gas reservoir single layer or multiple layers, thereby simulating the multi-layer commingling production of the gas reservoir.

[0038] The experimental method for simulating the multi-layer commingling production of the gas reservoir comprises 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;

[0040] Step 2, the weighed core basic experimental materials are sequentially and horizontally laid in the gas storage unit to obtain each simulated gas reservoir; the flow guide hole 4 is formed on the side wall of the inner wellbore 1 according to the preset mining requirements and the position of the simulated gas reservoir to be mined, the inner wellbore 1 is inserted into the bottom of the outer wellbore 3 and screwed, and then placed into the gas storage unit until the outer wellbore 3 is in contact with the bottom of the bottommost simulated gas reservoir;

[0041] The inner wellbore 1 is detachable and replaceable, and the outer wall of the inner wellbore 1 can be provided with a flow guide hole 4 according to the mining requirement. The inner wellbore 1 with different flow guide hole positions can be replaced to realize single-layer mining or sequential mining or interval mining of multiple layers. When single-layer mining is performed, the flow guide hole 4 is only provided at the bottom of the outer wall of the inner wellbore 1 and the position corresponding to the bottommost simulated gas storage layer. When sequential mining or interval mining of multiple layers is performed, the flow guide hole 4 is provided at the position corresponding to the simulated gas storage layer to be mined on the outer wall of the inner wellbore 1 according to the mining mode.

[0042] Step 3, cover the cover plate with a middle through hole on the gas storage unit, place a pad on each corner of the cover plate, pressurize the cover plate and the gas storage unit by using a pressurizing device or a hydraulic device, increase the pressure of the hydraulic machine, conduct the pressure to the cover plate by extruding the pad, and thus the core-based experimental material in the gas storage unit is pressed and formed, and is left to stand for 24-48 hours for solidification;

[0043] The cover plate with a middle through hole can make the surplus part of the gas production inner wellbore 1 and the outer wellbore 3 pass through the through hole, so as to avoid deformation of the wellbore under stress during the compaction process. The pads placed on the four corners can leave the middle position empty to avoid vertical deformation of the gas production inner wellbore 1 and the outer wellbore 3 caused by direct contact with the hydraulic device. The hydraulic device or the pressurizing device is used for pressing and forming the gas storage unit;

[0044] Step 4, cast epoxy resin on the outside of the gas storage unit pressed and formed in step 3, and place the gas storage unit in a cool and dry place to wait for the epoxy resin to completely solidify, so as to obtain a simulated gas storage unit;

[0045] The epoxy resin is cast to make the gas storage unit a sealed whole, so as to ensure that each simulated gas storage layer bears the same confining pressure, and each simulated gas storage layer maintains a unified pore pressure through gas seepage between layers;

[0046] Step 5, place the simulated gas storage unit in step 4 in a high-pressure container, and apply confining pressure to the simulated gas storage unit to the rated pressure of the high-pressure container. At this 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 small compressibility. The high-pressure container is used for applying 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, fill the simulated gas storage unit with gas, close the gas production flow control valve when the pore pressure monitored by the pressure sensor 13 is 1-1.5 MPa less than the rated confining pressure, remove the external gas source to stop filling, and record the cumulative gas injection amount Q1 through the gas flow meter 9;

[0049] Step 7, open the flow control valve 8, and combine the multi-layers according to the preset exploitation demand in step 2, when the gas flow meter 9 monitors that the gas flow is less than 10 mL / 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, and end the experiment.

[0050] In step 7, the multi-layer combination is specifically as follows: when the pore pressure drops to the preset value of the current simulated gas reservoir, rotate the inner wellbore 1 outwards to the position where the flow guide hole 4 of the inner wellbore 1 near the top is located in the next layer of simulated gas reservoir, then tighten the inner wellbore 1 and the outer wellbore 3, and develop the next layer of simulated gas reservoir to be exploited, when the pore pressure drops again to the preset value of the simulated gas reservoir, continue to rotate the inner wellbore 1 outwards to the position where the flow guide hole 4 of the inner wellbore 1 near the top is located in the next layer of simulated gas reservoir, then tighten the inner wellbore 1 and the outer wellbore 3, and develop the next layer of simulated gas reservoir to be exploited, and repeat the above steps in sequence until the flow guide hole 4 of the inner wellbore 1 near the top is located in the last layer of simulated gas reservoir, then tighten the inner wellbore 1 and the outer wellbore 3, and develop the last layer of simulated gas reservoir, when the gas flow meter 9 monitors that the gas flow is less than 10 mL / 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, and end the experiment.

[0051] The working principle of the experimental device for simulating multi-layer combination of gas reservoirs according to the present application is as follows: the gas reservoirs are cast by epoxy resin, so that the confining pressures of the simulated gas reservoirs are unified, under the same confining pressure condition, different gas reservoir-gas production inner wellbore seepage channels are constructed by adjusting the position of the inner wellbore with different position flow guide holes, and then the gas reservoirs are inflated and exploited.

[0052] The experimental device and method for simulating multi-layer combination of gas reservoirs according to the present application have the advantages that: the relatively independent gas transmission pipelines of the simulated gas reservoirs can be established, and the gas reservoirs can be selectively developed; in the implementation process, the gas reservoirs can have a unified pressure system, which is consistent with the actual gas reservoir development situation; the multi-layer rock materials are pressed and formed at one time, and then packaged as a whole by epoxy resin, and only one pressure container is needed to apply confining pressure, without the need for parallel connection of multiple core clamps, so that the experimental steps of multi-layer combination of gas reservoirs are simplified.

[0053] Example 1

[0054] The experimental device for simulating multi-layer combination of gas reservoirs according to the present application has the structure as shown in Figure 1As shown in the figure, the device comprises a gas storage unit with a hollow structure, the gas storage unit is provided with a cover plate, a through hole is formed in the center of the cover plate, the outer wellbore 3 passes through the through hole and extends into the gas storage unit until the bottom of the gas storage unit, the top end of the inner wellbore 1 is connected with an external gas source through a flow control valve 8, the flow control valve 8 is connected with a gas flow meter 9 and a pressure sensor 13, three transverse simulated gas storage layers are arranged in the gas storage unit, which are 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 once press-formed, 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, so that the confining pressure of each simulated gas storage layer is uniform.

[0055] A layer metal partition plate 5 is horizontally fixed at a position corresponding to the junction of each adjacent two simulated gas storage layers on the inner wall of the outer wellbore 3, a threaded hole 6 is formed in the center of the layer metal partition plate 5, a sealing thread 2 is arranged on the outer wall of the inner wellbore 1, the sealing thread 2 is matched with the threaded hole 6, the layer separation is realized by the engagement of the sealing thread 2 and the threaded hole 6 of the layer metal partition plate, and the junction between the simulated gas storage layers is flush with the layer metal partition plate 5 by controlling the amount of diagenetic material required for a single gas layer. The edge of the layer metal partition plate 5 is closely attached to the inner wall of the outer wellbore 3, six pairs of fixed flow guide holes 7 are symmetrically formed in the side wall of the outer wellbore 3, two pairs of fixed flow guide holes 7 correspond to each gas storage layer, and the fixed flow guide holes 7 are connected with the gas storage layer. The outer wellbore 3 is in close contact with each simulated gas storage layer of the gas storage unit, so that the gas does not vertically flow on the contact surface between the outer wellbore 3 and each simulated gas storage layer.

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

[0057] Example 2

[0058] The experimental device for simulating multi-layer combined production of gas reservoirs of the application has the structure as Figure 1 shown in the figure, the device comprises a gas storage unit with a hollow structure, the gas storage unit is provided with a cover plate, a through hole is formed in the center of the cover plate, the outer wellbore 3 passes through the through hole and extends into the gas storage unit until the bottom of the gas storage unit, the top end of the inner wellbore 1 is connected with an external gas source through a flow control valve 8, the flow control valve 8 is connected with a gas flow meter 9 and a pressure sensor 13, three transverse simulated gas storage layers are arranged in the gas storage unit, which are 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 once press-formed, 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, so that the confining pressure of each simulated gas storage layer is uniform.

[0059] The inner wall of the outer wellbore 3 is fixedly connected with an interlayer metal partition plate 5 at a position corresponding to the junction of each two adjacent simulation gas reservoirs, the center of the interlayer metal partition plate 5 is provided with a threaded hole 6, the outer wall of the inner wellbore 1 is provided with a sealing thread 2, the sealing thread 2 is matched with the threaded hole 6, the separation between layers is realized by the engagement of the sealing thread 2 and the threaded hole 6 of the interlayer metal partition plate, and the junction between the simulation gas reservoirs is ensured to be flush with the interlayer metal partition plate 5 by controlling the amount of diagenetic material required by a single gas layer. The edge of the interlayer metal partition plate 5 is tightly attached to the inner wall of the outer wellbore 3, and the sidewall of the outer wellbore 3 is symmetrically provided with six pairs of fixed flow guide holes 7, each simulation gas reservoir is correspondingly provided with two pairs of fixed flow guide holes 7 and is communicated with the simulation gas reservoir through the fixed flow guide holes 7. The outer wellbore 3 is in close contact with each simulation gas reservoir of the gas storage unit, so that the gas cannot vertically flow on the contact surface between the outer wellbore 3 and each simulation gas reservoir.

[0060] The sidewall of the inner wellbore 1 is provided with two pairs of flow guide holes 4 at positions corresponding to the first simulation gas reservoir 10, the second simulation gas reservoir 11 and the third simulation gas reservoir 12, and the three layers are simultaneously produced.

[0061] Example 3

[0062] The experimental device for simulating multi-layer commingling production of a gas reservoir according to the present application has a structure as shown in Figure 1 The experimental device for simulating multi-layer commingling production of a gas reservoir according to the present application has a structure as shown in

[0063] The inner wall of the outer wellbore 3 is fixedly connected with an interlayer metal partition plate 5 at a position corresponding to the junction of each two adjacent simulation gas reservoirs, the center of the interlayer metal partition plate 5 is provided with a threaded hole 6, the outer wall of the inner wellbore 1 is provided with a sealing thread 2, the sealing thread 2 is matched with the threaded hole 6, the separation between layers is realized by the engagement of the sealing thread 2 and the threaded hole 6 of the interlayer metal partition plate, and the junction between the simulation gas reservoirs is ensured to be flush with the interlayer metal partition plate 5 by controlling the amount of diagenetic material required by a single gas layer. The edge of the interlayer metal partition plate 5 is tightly attached to the inner wall of the outer wellbore 3, and the sidewall of the outer wellbore 3 is symmetrically provided with six pairs of fixed flow guide holes 7, each simulation gas reservoir is correspondingly provided with two pairs of fixed flow guide holes 7 and is communicated with the simulation gas reservoir through the fixed flow guide holes 7. The outer wellbore 3 is in close contact with each simulation gas reservoir of the gas storage unit, so that the gas cannot vertically flow on the contact surface between the outer wellbore 3 and each simulation gas reservoir.

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

[0065] Example 4

[0066] The experimental apparatus for simulating multi-layer synergistic gas production in this invention has the following structure: Figure 1 As shown, the gas storage unit includes a hollow structure. One end of the outer wellbore 3 extends into the gas storage unit to the bottom. The top of the inner wellbore 1 is connected to an 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 transverse simulated gas storage layers are set inside 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 formed by pressing in one piece. The gas seepage between the layers makes the pore pressure of each simulated gas storage layer uniform. The gas storage unit is encapsulated with epoxy resin casting to make the confining pressure of each simulated gas storage layer uniform.

[0067] At the junction of the inner wall of the outer wellbore 3 and each adjacent simulated gas reservoir, interlayer metal partition plates 5 are horizontally fixed. Each interlayer metal partition plate 5 has a threaded hole 6 at its center. The outer wall of the inner wellbore 1 is provided with sealing threads 2, which match the threaded holes 6. The separation between layers is achieved by the engagement of the sealing threads 2 and the threaded holes 6 of the interlayer metal partition plates. The amount of diagenetic material required for each gas reservoir is controlled to ensure that the junctions between the simulated gas reservoirs are flush with the interlayer metal partition plates 5. 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 sidewall of the outer wellbore 3, with two pairs of fixed guide holes 7 corresponding to each gas reservoir, and the gas reservoirs are connected through the fixed guide holes 7. The outer wellbore 3 is in close contact with each simulated gas reservoir of the gas storage unit, preventing vertical gas flow at the contact surface between the outer wellbore 3 and each simulated gas reservoir.

[0068] A pair of guide holes 4 are symmetrically opened on the side wall of the inner wellbore 1 at the position corresponding to the first simulated gas storage layer 10, and two pairs of guide holes 4 are symmetrically opened on the side wall of the inner wellbore 1 at the position 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 extracted at the same time.

[0069] Example 5

[0070] The experimental method for simulating multi-layer synergistic gas reservoir production of the present invention uses the experimental apparatus of Embodiment 1 of the present invention and is implemented according to the following steps:

[0071] Step 1: According to the porosity of each layer in Table 1 below and penetration rate K i The requirement is to prepare three types of artificial rock core basic experimental materials;

[0072] Table 1 each simulation layer pore permeability requirements

[0073]

[0074] According to the thickness of each simulation gas reservoir, the mass of the core-based experimental material required for each simulation gas reservoir is determined, and three kinds of diagenetic materials are weighed respectively;

[0075] Step 2, add the core-based experimental materials in the order of the actual reservoir space, first pour the third layer of artificial core-based experimental material into the bottom of the gas storage unit, then add the second layer of artificial core-based experimental material, and finally add the first layer of artificial core-based experimental material, to obtain each simulation gas reservoir; the preset production requirement is to produce two layers at a time, from bottom to top, and two pairs of flow holes 4 are respectively arranged on the inner wellbore 1 side wall corresponding to the second simulation gas reservoir 11 and the third simulation gas reservoir 12, and the inner wellbore 1 is screwed into the bottom of the outer wellbore 3, and then placed into the gas storage unit until the outer wellbore 3 contacts the bottommost simulation gas reservoir;

[0076] Step 3, cover the gas storage unit with a cover plate with a hole in the middle, place four blocks on the four corners of the cover plate, and use a hydraulic device to pressurize the cover plate, the blocks and the gas storage unit, so that the core-based experimental material in the gas storage unit is pressed and formed, and is left to solidify for 24 hours;

[0077] Step 4, cast epoxy resin on the outside of the gas storage unit after pressing and forming in step 3, and form an encapsulation layer of about 0.5-2.0 cm on its surface; place it in a cool and dry place until the epoxy resin is completely cured to obtain a simulation gas storage unit;

[0078] Step 5, place the simulation gas storage unit in step 4 in a pressure chamber, and apply confining pressure to the simulation gas storage unit to the rated pressure of the pressure chamber 10 MPa, and the pressure transmission medium is water, at this time the confining pressure of the simulation 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, the flow control valve 8 is connected 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 simulation gas storage unit with gas, stop when the pore pressure monitored by the pressure sensor 13 rises to 9 MPa, close the gas production flow control valve 8, remove the external gas source to stop filling, and record the cumulative gas injection amount Q1 as 203 L through the gas flow meter 9;

[0080] Step 7, open the flow control valve 8, at this time, the second and third simulated gas reservoirs 11 and 12 are developed simultaneously, when the pore pressure drops to the preset value 6MPa, the inner wellbore 1 is rotated to the position close to the top of the inner wellbore 1, the flow guide hole 4 is located in the first simulated gas reservoir 10, the inner wellbore 1 and the outer wellbore 3 are tightened, at this time, the first and second simulated gas reservoirs 10 and 11 are developed simultaneously, when the gas flow meter 9 monitors that the gas flow is less than 10mL / min, the flow control valve 8 is closed, the cumulative gas production Q2 is recorded as 193L by the gas flow meter 9, and the inner wellbore 1 is rotated out, and the experiment is ended.

[0081] Example 6

[0082] The experimental method for simulating gas reservoir multi-layer commingling production of the application is implemented according to the following steps by using the experimental device of Example 4 of the application:

[0083] Steps 1-2 are the same as those in Example 5, in step 3, the solidification is performed by standing for 48h, and the rest is the same as that in Example 5, steps 4-6 are the same as those in Example 5, and the cumulative gas injection amount Q1 is recorded as 203L;

[0084] Step 7, open the flow control valve 8, at this time, the second and third simulated gas reservoirs 11 and 12 are developed simultaneously, when the gas flow meter 9 monitors that the gas flow is less than 10mL / min, the flow control valve 8 is closed, the cumulative gas production Q2 is recorded as 193L by the gas flow meter 9, and the inner wellbore 1 is rotated out, and the experiment is ended.

Claims

1. An experimental apparatus for simulating multi-layer synergistic gas production in a gas reservoir, characterized in that, It includes a gas storage unit and a wellbore inserted inside 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. The other end of the wellbore is connected to an 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). Multiple transverse simulated gas storage layers are set inside the gas storage unit. The wellbore includes an outer wellbore (3), the bottom of which extends to the bottom of the gas storage unit. At the position corresponding to the junction of the inner wall of the outer wellbore (3) and each of the two adjacent simulated gas storage layers, an interlayer metal partition plate (5) is horizontally fixed. Each interlayer metal partition plate (5) has a threaded hole (6) at its center. An inner wellbore (1) is connected to the threaded hole (6) through which the inner wellbore (1) is fixed. The outer wellbore (3) has several pairs of fixed guide holes (7) symmetrically opened on its sidewall. The outer wellbore (3) is closely attached to the simulated gas storage layer and is connected to each of the gas storage layers through the fixed guide holes (7). Sealing threads (2) are provided at the bottom of the outer wall of the inner well casing (1) and at the position corresponding to the threaded hole (6), and the sealing threads (2) are matched with the threaded hole (6); The inner wellbore (1) has symmetrically arranged guide holes (4) at the positions corresponding to the simulated gas storage layer on its side wall. The guide holes (4) are located between two adjacent sealing threads (2). The inner wellbore (1) is detachable. By replacing the inner wellbore (1) with different positions of the guide holes (4), continuous or intermittent mining of each simulated gas storage layer can be achieved.

2. The experimental apparatus for simulating multi-layer synergistic gas reservoir production according to claim 1, characterized in that, The gas storage unit is equipped with a cover plate with a through hole in the center, through which the well shaft passes.

3. An experimental method for simulating multi-layer synergistic gas production in a gas reservoir, characterized in that, The experimental apparatus for simulating multi-layer synergistic gas reservoir production as described in claim 1 or 2 is implemented according to the following steps: Step 1: Select the core foundation experimental materials required for each simulated gas reservoir, determine the mass of the core foundation experimental materials required for each simulated gas reservoir based on the thickness of a single simulated gas reservoir, and weigh them. Step 2: The weighed core foundation experimental materials are laid horizontally into the gas storage unit in sequence to obtain each simulated gas storage layer; according to the preset mining requirements and the location of the simulated gas storage layer to be mined, the guide hole (4) is opened on the outer wall of the inner well barrel (1). After the inner well barrel (1) is inserted into the bottom of the outer well barrel (3) and screwed tightly, it is placed into the gas storage unit until the outer well barrel (3) contacts the bottom of the lowest simulated gas storage layer. 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 compress the core foundation experimental material in the gas storage unit into shape and let it solidify. Step 4: Cast epoxy resin onto the outside of the gas storage unit after pressing and molding in step 3, and cure to obtain the simulated gas storage unit; Step 5: Place the simulated gas storage unit from Step 4 into the high-pressure container and apply confining pressure to the simulated gas storage unit to the rated pressure of the high-pressure container. At this time, the confining pressure of the simulated gas storage unit is the rated confining pressure. Step 6: Connect the flow control valve (8) to the top of the inner wellbore (1). Connect the flow control valve (8) to the body flow meter (9), pressure sensor (13) and external gas source. Open the external gas source and the flow control valve (8) to 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 1~1.5MPa lower 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 perform multi-layer combined mining according to the preset mining requirements in Step 2. When the gas flow meter (9) monitors the gas flow rate as less than 10 mL / min, close the flow control valve (8) and record the cumulative gas extraction volume through the gas flow meter (9). Q 2. Rotate out the inner well casing (1) to end the experiment; In step 7, the multi-layer combined mining 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. Then, the inner wellbore (1) and the outer wellbore (3) are tightened, and the development of the next simulated gas reservoir to be mined is carried out. When the pore pressure drops to the experimental preset value of the simulated gas reservoir again, 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. After one simulated gas reservoir layer is formed, the inner wellbore (1) and outer wellbore (3) are tightened, and the next simulated gas reservoir layer to be developed is started. This process is repeated until the guide hole (4) near the top of the inner wellbore (1) is located in the last simulated gas reservoir layer. The inner wellbore (1) and outer wellbore (3) are tightened, and the last simulated gas reservoir layer is developed. When the gas flow meter (9) detects that the gas flow rate is less than 10 mL / min, the flow control valve (8) is closed, and the cumulative gas production is recorded by the gas flow meter (9). Q 2. Rotate out the inner well tube (1) to end the experiment.

4. The experimental method for simulating multi-layer synergistic gas reservoir production according to claim 3, characterized in that, In step 2, the settling time is 24~48h; in step 3, a pad is provided between the cover plate and the pressurizing device.

5. The experimental method for simulating multi-layer synergistic gas reservoir production according to claim 3, characterized in that, In step 5, the conductive medium of the high-pressure vessel is selected as a liquid fluid with low compressibility.

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