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

Abstract

The simulation gas reservoir multi-layer combined production experimental device comprises a gas storage unit, the gas storage unit is formed by sequentially aligning and stacking a plurality of simulation gas layers, a multi-layer combined production wellbore is arranged at a central position in the gas storage unit, the bottom is aligned, a gas production interface is arranged at the top end of the multi-layer combined production wellbore, the gas production interface is sequentially connected with a pressure gauge, a flow regulating valve and an external gas source through pipelines; the experimental method of the present application comprises the following steps: selecting simulation gas layer materials and a wellbore, pressing and forming, gluing, epoxy resin pouring, pressure application and gas filling, and carrying out gas storage production according to requirements. The simulation gas reservoir multi-layer combined production experimental device and experimental method have the advantages of less equipment, the application of various development schemes on the same model, the pressing and forming of diagenetic materials, the consolidation of adjacent two simulation gas layers, the continuous distribution of the internal pressure profile of the model during development, simple and flexible operation, cost and time saving.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas reservoir recovery technology, specifically relating to a simulated multi-layer synergistic production experimental device for gas reservoirs, and also to a simulated multi-layer synergistic production experimental method for gas reservoirs. Background Technology

[0002] For gas reservoirs with multiple producing layers, differences in pressure, temperature, and fluid properties during reservoir formation lead to significant variations in porosity, permeability, and water saturation among the layers, resulting in varying production capacities. For high-productivity reservoirs, rapid natural gas production leads to rapid formation energy depletion, making subsequent production enhancement operations difficult. Conversely, for low-productivity reservoirs, economic benefits are poor, making it difficult to achieve production enhancement targets. Developing such gas reservoirs using the same wellbore makes it impossible to obtain dynamic production data for individual gas layers, and it cannot be guaranteed that the production regime used is suitable for each reservoir, thus causing uneven utilization of gas reserves.

[0003] Multi-layer synergistic development is an important technical means to achieve efficient and economical utilization of gas reservoir reserves. On the one hand, it develops multiple producing layers simultaneously with relatively independent seepage channels, ensuring efficient development of the gas reservoir without inter-layer interference; on the other hand, multi-layer synergistic development technology can achieve control over individual producing layers, and achieve balanced utilization of reserves in each layer by controlling its production pressure differential.

[0004] Currently, most scholars use the method of parallel connection of multiple core holders to simulate the multi-layer synergistic production process of gas reservoirs. However, this method ignores the problem that a single well cannot be used to develop a single reservoir in the actual multi-layer synergistic production process of gas reservoirs. In addition, the holders completely isolate multiple simulated gas layers, resulting in discontinuous pressure profiles in the vertical direction. It is difficult to determine the pressure field of the actual gas reservoir based on such experimental results, and the judgment of the reserve utilization of each producing layer is not accurate enough. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-layer synergistic production experimental device for simulating gas reservoirs, which can develop multiple simulated gas layers with a single gas well and can flexibly adjust the combination of the developed layers and the production rate.

[0006] Another objective of this invention is to provide a simulated multi-layer synergistic gas reservoir production experimental method, which features a simulated environment that closely matches the actual development situation.

[0007] The technical solution adopted in this invention is a multi-layer synergistic production experimental device for simulating gas reservoirs, including a gas storage unit. The gas storage unit is formed by stacking and pressing several simulated gas layers in sequence. A multi-layer synergistic production wellbore is installed at the center of the gas storage unit. A guide hole is opened on the outer periphery of the multi-layer synergistic production wellbore. The multi-layer synergistic production wellbore is a composite development wellbore or a rotary development wellbore. One end of the multi-layer synergistic production wellbore is in contact with the bottom of the gas storage unit, and the other end of the multi-layer synergistic production wellbore is located outside the gas storage unit and is provided with a gas production interface. The gas production interface is connected to a pressure gauge and a flow regulating valve in sequence through a pipeline. The flow regulating valve is connected to an external gas source, and a flow meter is connected between the flow regulating valve and the external gas source.

[0008] The invention is further characterized by:

[0009] The multi-layered syngas wellbore is a composite development wellbore, comprising several gas production wellbores sealed at both ends. Each gas production wellbore is nested and fixed to the others, and the length of each gas production wellbore increases sequentially from the center at both ends from the outside to the inside. The number of gas production wellbores corresponds to the number of simulated gas layers. Each gas production wellbore has a gas production interface at its top. The lower section of each gas production wellbore corresponds to each simulated gas layer. The bottom end of the innermost gas production wellbore contacts the bottom of the bottommost simulated gas layer, and the bottom end of the outermost gas production wellbore abuts against the bottom of the topmost simulated gas layer. Each gas production wellbore corresponding to each simulated gas layer has several first guide holes symmetrically opened in its lower section.

[0010] The multi-layer combined production wellbore is a rotary development wellbore, including a hollow cylindrical gas production inner wellbore. The bottom end of the gas production inner wellbore is in contact with the bottom of the gas storage unit, and the top end of the gas production inner wellbore is located outside the gas storage unit and is equipped with a gas production interface.

[0011] The inner wellbore of the gas production area is fitted with a fixed outer wellbore. The fixed outer wellbore is tightly fitted with the inner wellbore of the gas production area, and the bottom end of the fixed outer wellbore is aligned with the bottom end of the inner wellbore of the gas production area. The fixed outer wellbore has a cylindrical structure, and the length of the inner wellbore of the gas production area is greater than the length of the fixed outer wellbore.

[0012] Two rows of external guide holes are symmetrically opened on the outer periphery of each section corresponding to each simulated gas layer, and the external guide holes of each section are located in the same upward row.

[0013] The rotation angle of the gas production wellbore is α = 180° / ( The gas production wellbore and each section of the simulated gas layer have multiple rows of internal guide holes symmetrically opened on their outer periphery. The internal guide holes on each section are staggered or the same according to the rotation angle α and the production requirements. The internal guide holes are matched with the external guide holes.

[0014] Each gas sampling interface is equipped with a connector.

[0015] The external gas source is a high-pressure N2 gas cylinder.

[0016] Another technical solution adopted in this invention is a simulated multi-layer synergistic production test method for gas reservoirs, using the aforementioned simulated multi-layer synergistic production test device. The specific steps are as follows:

[0017] Step 1. Determine the experimental parameters based on the actual sequence and thickness of each producing layer in the gas reservoir;

[0018] Step 2. Prepare each simulated gas layer and multi-layer commingled wellbore according to the experimental parameters and press them into shape;

[0019] Step 3. Apply adhesive to the surface of the pressed physical model and cast it with epoxy resin to obtain the experimental model;

[0020] Step 4. Place the experimental model in the high-pressure vessel, and connect each gas sampling port to the external pressure gauge, flow regulating valve, flow meter, and external gas source in sequence; apply pressure, and stop applying pressure when the confining pressure rises to the actual pressure;

[0021] Step 5. Open the external gas source and flow control valve, fill with gas, adjust the flow control valve and multi-layer combined wellbore. When the pressure on each pressure gauge is 1.5~2.0MPa lower than the confining pressure, close the flow control valve and remove the external gas source. Record the cumulative flow.

[0022] Step 6. Open the flow regulating valve and carry out gas storage and extraction according to development needs; when the gas extraction flow rate is less than 10 mL / min, calculate the cumulative gas extraction volume and end the experiment.

[0023] Another feature of the technical solution of this invention is that:

[0024] In step 1, the experimental parameters include the number of each simulated gas layer, the thickness and physical properties of each simulated gas layer, and the type and quality of the artificial rock core base material required for each simulated layer.

[0025] Step 2 specifically involves determining the type and quality of artificial core base materials required for each simulated gas layer based on experimental parameters. After weighing each base material, the base materials of the same layer are mixed evenly and reserved. The mixed base materials are then laid into the artificial core mold in the actual order of each gas reservoir production layer. The type, height, and position of the multi-layer combined production wellbore are determined. After the multi-layer combined production wellbore is assembled, it is vertically buried in the center of the base material, with the bottom in contact with the bottom of the mold. The mold is then moved into a pressurizing device, and a cover plate with a hole in the middle is added. The upper end of the multi-layer combined production wellbore passes through the round hole. The cover plate is pressurized to compact the artificial core base material. After pressing, it is removed from the mold and left to stand until it is completely solidified to obtain the physical model.

[0026] In step 4, the pressure application specifically involves injecting a physicochemically stable liquid into the internal pores of the high-pressure vessel through the external interface to apply confining pressure to the experimental model. The confining pressure is monitored by the pressure gauge built into the high-pressure vessel, and the liquid injection is stopped when the confining pressure rises to the actual reservoir pressure.

[0027] Step 6, specifically the gas storage and extraction based on development needs, involves:

[0028] When the multi-layer combined wellbore is a composite development wellbore, a flow meter is connected after each flow regulating valve. According to the development needs, the flow regulating valve corresponding to the simulated gas layer is opened, and the multi-layer combined wellbore and the flow regulating valve are adjusted to carry out gas storage and extraction.

[0029] When the multi-layered commingled wellbore is a rotary development wellbore, the wellbore is rotated clockwise to the corresponding angle according to development needs for gas storage and extraction.

[0030] The beneficial effects of this invention are:

[0031] 1) Using artificial core technology, multiple simulated gas layers are combined according to the actual stratigraphic sequence, so that the pressure field between each layer is continuously distributed. Combined with the actual mine, multiple simulated gas layers can be developed with a single gas well, and the combination of developed layers and mining speed can be flexibly adjusted. During the development process, the on / off or production pressure difference of a single producing layer can be controlled, and the simulation experiments carried out in this way are more in line with the actual engineering.

[0032] 2) By pressing the diagenetic material into shape in one step, two adjacent simulated gas layers are solidified together without any separating device in between, so that the pressure profile inside the model is continuously distributed during the development process.

[0033] 3) Compared with the traditional method of simulating multi-layer gas reservoir co-production by parallel connection of multiple core holders, the present invention uses less equipment, can realize the application of multiple development schemes on the same model, is simple and flexible to operate, and saves experimental costs and time costs. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the experimental device for simulating multi-layer gas reservoir production according to the present invention;

[0035] Figure 2 This is a schematic diagram of the composite development wellbore of the simulated gas reservoir multi-layer synergistic production experimental device of the present invention;

[0036] Figure 3 This is a schematic diagram of the rotating development wellbore of the experimental device for simulating multi-layer gas reservoir production according to the present invention.

[0037] In the diagram, 1. First simulated gas layer, 2. Second simulated gas layer, 3. Third simulated gas layer, 4. Multi-layer combined production wellbore, 5. Pressure gauge, 6. Flow regulating valve, 7. Gas production interface of the third simulated layer, 8. Gas production interface of the second simulated layer, 9. Gas production interface of the first simulated layer, 10. Gas production wellbore of the first simulated layer, 11. First guide hole, 12. Gas production wellbore of the second simulated layer, 13. Gas production wellbore of the third simulated layer; 14. Gas production interface of the rotary development wellbore, 15. Inner gas production wellbore, 16. Fixed outer wellbore, 17. Outer guide hole, 18. Inner guide hole. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0039] The experimental device for simulating multi-layer synergistic gas production in this invention has the following structure: Figure 1 As shown, the system includes a gas storage unit, which is formed by stacking and pressing multiple horizontally arranged simulated gas layers. The sequence of the simulated gas layers follows the actual reservoir sequence, and the thickness of the simulated gas layers is controlled by adjusting the quality of the added diagenetic material and the order of assembly. A multi-layered wellbore 4 has one section located outside the gas storage unit and the other section inserted into the center of the gas storage unit. The bottom of the multi-layered wellbore 4 abuts against the bottom of the lowest simulated gas layer. The top of the multi-layered wellbore 4 is equipped with a gas extraction interface and connectors for connecting other pipelines. These connectors are connected sequentially to a pressure gauge 5 and a flow control valve 6 via pipes for monitoring the internal pressure and controlling the output flow rate. The flow control valve 6 is connected to an external gas source, a high-pressure N2 gas cylinder, used to fill the model with gas.

[0040] There are two types of multi-layer combined wellbore 4: composite development wellbore and rotary development wellbore. The choice can be made according to the mining needs. However, it is necessary to ensure that the bottom of the multi-layer combined wellbore 4 is flush with the lower boundary of the lowest simulated gas layer, and the uppermost guide hole of the multi-layer combined wellbore 4 is completely covered by the uppermost simulated gas layer. During the experiment, all gas production interfaces of the multi-layer combined wellbore 4 must be connected to pressure gauge 5 and flow regulating valve 6 in sequence for monitoring the internal pressure of the device and controlling the production flow.

[0041] Composite development wellbore structure such as Figure 2As shown, the device includes several gas collection wells with closed ends. These wells are concentrically connected and fixed to each other. From the outside to the inside, the length of each well increases sequentially from the center at both ends. The gas inside adjacent wells is isolated by the well walls. Each well has a gas collection interface at its top. The number of wells and gas collection interfaces corresponds to the number of simulated gas layers. Each gas collection interface is equipped with a connector. Each connector is connected to a pressure gauge 5 and a flow regulating valve 6 via pipes. These are used to monitor the internal pressure of the device and control the output flow rate. All flow regulating valves 6 are connected to an external gas source. A flow meter is connected between the flow regulating valves 6 and the external gas source, which is a high-pressure N2 gas cylinder.

[0042] The length of the lower section of each gas wellbore corresponds to the thickness of each simulated gas layer. Each lower section of the gas wellbore corresponds to one simulated gas layer. The bottom of the innermost gas wellbore contacts the bottom of the lowest simulated gas layer, and the bottom of the outermost gas wellbore abuts the bottom of the highest simulated gas layer. Each lower section of the gas wellbore corresponding to each simulated gas layer is symmetrically provided with several first guide holes 11. The number and diameter of the guide holes are set according to specific experimental requirements. Each gas wellbore has no other fluid channels except for the guide holes and the gas extraction interface. Gas enters the gas wellbore through the first guide holes 11 in the lower section of the gas wellbore and then flows out through the gas extraction interface at the top of the gas wellbore. During use, the flow regulating valve 6 connected to the gas extraction connector is adjusted to regulate the extraction speed of one or more gas layers.

[0043] The rotary development wellbore structure is shown in Figure 3. It includes a hollow cylindrical inner wellbore 15, whose bottom end abuts against the bottom of the gas storage unit, and whose top end is located outside the gas storage unit. A fixed outer wellbore 16 is fitted over the inner wellbore 15, tightly fitting against it. The fixed outer wellbore 16 has a cylindrical structure, and its bottom end is aligned with the bottom end of the inner wellbore 15. The length of the inner wellbore 15 is greater than the length of the fixed outer wellbore 16. A rotary development wellbore gas production connector 14 is located at the top of the inner wellbore 15 and is equipped with… The connector is connected in sequence to a pressure gauge 5 and a flow regulating valve 6 via pipes. These are used to monitor the internal pressure of the device and control the output flow rate. The flow regulating valve 6 is connected to an external gas source, which is a high-pressure N2 gas cylinder. A flow meter is connected between the flow regulating valve 6 and the external gas source. Two rows of external guide holes 17 are symmetrically opened on the outer periphery of each section corresponding to each simulated gas layer in the fixed outer wellbore 16. The external guide holes 17 in each section are located in the same upward-facing row. The number and diameter of the external guide holes 17 are set according to specific experimental requirements. The size of the internal guide holes 18 in each section is the same as the external guide holes 17, and both can be rotated to coincide with the external guide holes 17. By rotating the gas production inner wellbore 15 at different angles, single-layer or multi-layer simulated gas layer combination development can be achieved.

[0044] After assembling the inner wellbore 15 and the fixed outer wellbore 16 together, ensure that the lower ends are flush and the starting point scale lines of the rotation angle of the two wellbores are aligned. The inner wellbore 15 rotates by an angle α = 180° / ( ), where n is the number of simulated gas layers, The sum of the number of development schemes, where 1 represents the case of not developing the gas layer, used to shut down model gas production. This represents the number of development schemes that select one gas layer for extraction from a model with n simulated gas layers. This indicates the number of development schemes that can be selected from a model with n simulated gas layers for extraction, and so on, until all n simulated gas layers are extracted. Alternatively, several development schemes can be selected based on actual needs. Multiple rows of internal guide holes 18 are symmetrically opened on the outer periphery of each section corresponding to each simulated gas layer in the gas production inner wellbore 15. The internal guide holes 18 on each section are staggered or aligned according to the rotation angle α and extraction requirements. That is, after rotating the gas production inner wellbore 15 by α, a set of internal guide holes 18 is symmetrically arranged along the axis on the well wall of the gas production inner wellbore 15 to achieve one development scheme. After rotating by α again, another set of internal guide holes 18 is symmetrically arranged along the axis on the well wall of the gas production inner wellbore 15 to achieve another development scheme, until all development scheme internal guide holes 18 are arranged. By rotating the gas production inner wellbore 15, the internal guide holes 18 corresponding to each development scheme are aligned with the external guide holes 17 of the fixed outer wellbore 16, thereby realizing the combined extraction of simulated gas layers.

[0045] The working principle of the simulated gas reservoir multi-layer synergistic production device of this invention is as follows: relying on the close contact between the simulated gas layer and the outer wall of the wellbore, there is no gas flow between the simulated gas layers. The gas can only flow through the wellbore guide holes. Then, an independent fluid flow channel is constructed for the individual or combined production of each simulated gas layer. By controlling the flow rate at the outlet of each flow channel, the single-layer or multi-layer development of the gas layer can be realized. The device requires less equipment, can realize the application of multiple development schemes on the same model, and is simple and flexible to operate, saving experimental costs and time costs.

[0046] The simulated gas reservoir multi-layer synergistic production experimental method of the present invention uses the above-mentioned simulated gas reservoir multi-layer synergistic production experimental apparatus and is implemented according to the following steps:

[0047] Step 1: Determine the experimental parameters based on the actual sequence and thickness of each producing layer in the gas reservoir;

[0048] The experimental parameters include the number of each simulated gas layer, the thickness and physical properties of each simulated gas layer, and the type and quality of the artificial rock core base material required for each simulated layer.

[0049] Step 2: Determine the type and quality of artificial core base materials required for each simulated gas layer based on experimental parameters. After weighing each base material, mix the base materials of the same layer evenly and set aside. According to the actual sequence of each production layer of the gas reservoir, lay the mixed base materials into the artificial core mold in sequence. Determine the type, height and position of the guide hole of the multi-layer combined production wellbore 4. After the multi-layer combined production wellbore 4 is assembled, it is vertically buried in the center of the base material, with the bottom in contact with the bottom of the mold. Then, move the mold into the pressurizing device, cover it with a cover plate with a hole in the middle, and pressurize the cover plate to compact the artificial core base material, ensuring that the multi-layer combined production wellbore 4 is in close contact with the core material, so that the gas does not flow along the outer wall of the multi-layer combined production wellbore 4, and that the guide holes of each section of the multi-layer combined production wellbore 4 are located in the middle of the developed simulated gas layer. After pressing, remove it from the mold and let it stand until it is completely solidified to obtain the physical model.

[0050] Step 3: Apply a layer of guar gum to the surface of the physical model and let it dry to prevent the epoxy used in subsequent processes from seeping into the physical model; then cast epoxy resin, avoiding each gas sampling interface, so that the surface is completely covered by epoxy resin. After standing and curing, the experimental model is obtained.

[0051] Step 4: Move the experimental model into the high-pressure pressure vessel, and then connect each gas sampling interface to the external pressure gauge 5 and flow regulating valve 6 in sequence through pipelines. Then connect each flow regulating valve 6 to the same flow meter, and connect the flow meter to the high-pressure N2 gas cylinder. Close all flow regulating valves 6.

[0052] A chemically stable liquid is injected into the internal voids of a high-pressure vessel through its external interface to apply confining pressure to the experimental model. P 围 The confining pressure is monitored by the pressure gauge built into the high-pressure vessel. When the confining pressure... P 围 Stop injection when the actual reservoir pressure is reached;

[0053] Step 5: Open the high-pressure N2 gas cylinder and flow control valve 6 to fill the experimental model with gas. Align the guide holes of each wellbore in the multi-layer combined mining wellbore 4, and adjust the flow control valve 6 to adjust the pressure of each pressure gauge 5. P p Simultaneous rise, until all pressures P p Compared to confining pressure P 围 Stop charging when the pressure is 1.5~2.0MPa, close the flow regulating valve 6 or rotate the gas production wellbore 15 to the fully closed position, record the cumulative flow Q1 monitored by the gas flow meter, and remove the high-pressure N2 gas cylinder;

[0054] Step 6: Open the flow regulating valve 6 and carry out gas storage and extraction according to development needs; when the gas extraction flow rate is less than 10 mL / min, record the cumulative readings of each flow meter, sum them up to obtain the cumulative gas extraction volume Q2, and end the experiment.

[0055] Step 6, specifically the gas storage and extraction based on development needs, involves:

[0056] When the multi-layer combined production wellbore 4 is a composite development wellbore, a flow meter is connected after each flow regulating valve 6. According to the development needs, the flow regulating valve 6 corresponding to the simulated gas layer to be developed is opened, and the multi-layer combined production wellbore 4 and the flow regulating valve 6 are adjusted to carry out gas storage and extraction.

[0057] When the multi-layered communal wellbore 4 is a rotary development wellbore, the gas production inner wellbore 15 of the development wellbore is rotated clockwise to the corresponding angle according to the development needs for gas storage and extraction.

[0058] The advantages of the simulated gas reservoir multi-layer synergistic production experimental method of the present invention are as follows: multiple simulated gas layers are combined together according to the actual stratigraphic sequence using artificial core technology, so that the pressure field between each layer is continuously distributed. Combined with the actual mining situation, a single simulated gas well is used to realize the joint development of multiple producing layers. Furthermore, the on / off or production pressure difference of a single producing layer can be controlled during the development process, making the simulation experiment more consistent with engineering practice. By pressing the diagenetic material into shape in one step, adjacent simulated gas layers are solidified together without any separating device in between, so that the internal pressure profile of the model is continuously distributed during the development process.

[0059] Example 1

[0060] The experimental device for simulating multi-layer synergistic gas production in this invention has the following structure: Figure 1 and Figure 2 As shown, it includes a gas storage unit, which is formed by stacking and pressing the first simulated gas layer 1, the second simulated gas layer 2, and the third simulated gas layer 3 in sequence. All three simulated gas layers are arranged horizontally. The multi-layer combined production wellbore 4 is a composite development wellbore, including the first simulated gas layer production wellbore 10, the second simulated gas layer production wellbore 12, and the third simulated gas layer production wellbore 13, which correspond to the production of each simulated gas layer. All three production wellbores are closed at both ends. Each production wellbore is connected and fixed to each other in a concentric circle. From the outside to the inside, the length of each production wellbore increases sequentially from the center at both ends. The third simulated gas layer production wellbore 13 is the longest, and the first simulated gas layer production wellbore 10 is the shortest. The gas inside the adjacent wellbores is isolated by the well wall.

[0061] The top of the third simulated layer gas wellbore 13 is provided with a third simulated layer gas intake interface 7. The third simulated layer gas intake interface 7 is connected to a pressure gauge 5 and a flow regulating valve 6. The lower section of the third simulated layer gas wellbore 13 has the same length as the thickness of the third simulated gas layer 3. The bottom end of the third simulated layer gas wellbore 13 is aligned with the bottom of the third simulated gas layer 3. A first guide hole 11 is provided at the position corresponding to the third simulated gas layer 3.

[0062] The top of the second simulated layer gas wellbore 12 is provided with a second simulated layer gas production interface 8. The second simulated layer gas production interface 8 is connected to a pressure gauge 5 and a flow regulating valve 6. The lower section of the second simulated layer gas wellbore 12 has the same length as the thickness of the second simulated gas layer 2. The bottom end of the second simulated layer gas wellbore 12 is aligned with the bottom of the second simulated gas layer 2. A first guide hole 11 is provided at the position corresponding to the second simulated gas layer 2.

[0063] The first simulated layer gas production wellbore 10 is provided with a first simulated layer gas production interface 9 at the top. The first simulated layer gas production interface 9 is connected to a pressure gauge 5 and a flow regulating valve 6. The lower section of the first simulated layer gas production wellbore 10 has the same length as the thickness of the first simulated gas layer 1. The bottom end of the first simulated layer gas production wellbore 10 is aligned with the bottom of the first simulated gas layer 1. A first guide hole 11 is provided at the position corresponding to the first simulated gas layer 10.

[0064] The three gas production wells correspond to the extraction of three simulated gas layers, and the three flow control valves 6 are all connected to a high-pressure N2 gas cylinder; a flow meter is connected between the flow control valves 6 and the high-pressure N2 gas cylinder. Gas enters the gas production well through the guide hole in the lower section of the well and then flows out from the gas production interface at the top of the well. During use, the extraction rate of one or more gas layers can be adjusted by adjusting the flow control valves 6 connected to the gas production connector.

[0065] The specific implementation steps of the simulated multi-layer synergistic gas reservoir production experimental method of the present invention are as follows:

[0066] Step 1: According to the porosity of each layer in Table 1 below and penetration rate Requirements: Prepare three types of artificial core basic experimental materials. The thickness of each of the three simulated gas layers is 3cm. Weigh 3kg of 400-mesh quartz sand for each layer. The cement content from top to bottom is 14%, 16%, and 18%, respectively. After mixing, spread them evenly into the mold.

[0067] Table 1 Pore permeability requirements for each simulated layer

[0068]

[0069] Step 2: According to the actual sequence of each producing layer in the gas reservoir, the mixed base material is laid into the artificial core mold in sequence, from top to bottom as the first, second, and third simulated layers. For the multi-layer combined production wellbore 4, a composite development wellbore is selected. The composite development wellbore is vertically buried in the center of the base material, with its bottom in contact with the bottom of the mold. Then, a cover plate with a hole in the middle is added, so that the upper end of the composite development wellbore passes through the round hole. The mold is moved into the pressurizing device to pressurize the cover plate to compact the artificial core base material, ensuring that the composite development wellbore and the core material are in close contact, so that the gas does not flow along the well wall. The guide holes on each section of the composite development wellbore are located in the middle of the simulated gas layer being developed. After pressing, it is taken out and left to stand for 24 hours until it is completely solidified to obtain the physical model.

[0070] Step 3: Apply a layer of guar gum to the surface of the physical model and let it stand for 12 hours to dry, in order to prevent the epoxy used in subsequent processes from seeping into the physical model; then cast epoxy resin avoiding each gas sampling interface, and make sure that the surface is completely covered with 1 cm thick epoxy resin without blocking each gas sampling interface. After the epoxy resin has cured for 24 hours, the experimental model is obtained.

[0071] Step 4: Move the experimental model into the high-pressure chamber, and then connect each gas sampling interface to the external pressure gauge 5 and flow regulating valve 6 in sequence through pipelines. Connect each flow regulating valve 6 to the same flow meter, connect the flow meter to the high-pressure N2 gas cylinder, and close all flow regulating valves 6.

[0072] Step 5: Inject water into the internal voids of the high-pressure chamber through the external interface to apply a confining pressure P to the experimental model. Stop injecting when the pressure reaches 10 MPa.

[0073] Step 6: Open the flow regulating valve 6 and the high-pressure N2 gas cylinder, and adjust the flow regulating valve 6 to fill the model with gas, so that the pressure Pp of the pressure gauges 5 connected to each gas sampling interface rises synchronously until each pressure Pp reaches 8.5MPa. Stop filling, close the flow regulating valve 6, record the cumulative flow Q1 monitored by the gas flow meter as 256L, and remove the high-pressure N2 gas cylinder.

[0074] Step 7: Connect a flow meter after each flow regulating valve 6, and open the flow regulating valves 6 of the first simulated gas well 10 and the third simulated gas well 13; slowly adjust the flow regulating valves 6 to simulate production at a production rate of 400 mL / min. When the gas production flow rate is less than 10 mL / min, end the experiment, record the cumulative gas production Q2 as 243 L, and unload all pressure.

[0075] Example 2

[0076] The experimental device for simulating multi-layer synergistic gas production in this invention has the following structure: Figure 1 and Figure 3As shown, the system includes a gas storage unit, which is formed by stacking and pressing a first simulated gas layer 1, a second simulated gas layer 2, and a third simulated gas layer 3 in sequence. All three simulated gas layers are arranged laterally. The multi-layered combined production wellbore 4 is a rotary development wellbore, including a hollow cylindrical inner production wellbore 15. The bottom end of the inner production wellbore 15 abuts against the bottom of the gas storage unit, and the top end of the inner production wellbore 15 is located outside the gas storage unit. A fixed outer wellbore 16 is fitted over the inner production wellbore 15. The inner production wellbore 15 is a metal cylinder with upper and lower bottom surfaces, whose outer diameter is slightly smaller than the inner diameter of the fixed outer wellbore 16. The fixed outer wellbore 16 is tightly fitted to the gas production inner wellbore 15. The fixed outer wellbore 16 is a metal cylinder without bottom surfaces at the top and bottom, and its bottom end is aligned with the bottom end of the gas production inner wellbore 15. The rotary development wellbore gas production connector 14 is located at the top of the gas production inner wellbore 15. The rotary development wellbore gas production connector 14 is equipped with a connector, which is connected in sequence to a pressure gauge 5 and a flow regulating valve 6 via pipelines. These are used to monitor the internal pressure of the device and control the output flow rate. The flow regulating valve 6 is connected to a high-pressure N2 gas cylinder. A flow meter is connected between the flow regulating valve 6 and the external gas source.

[0077] The fixed outer wellbore 16 has a height of 9cm, and the gas production inner wellbore 15 has a length greater than that of the fixed outer wellbore 16. Two rows of external guide holes 17 are symmetrically arranged at heights of 0~3cm, 3~6cm, and 6~9cm on the fixed outer wellbore 16, with each section of the external guide holes 17 located in the same upward row. When n is 3, the rotation angle α of the gas production inner wellbore 15 is 180° / ( =22.5°, with internal guide holes 18 arranged along the column direction at the uppermost section of the gas production inner wellbore 15 at 22.5° and 202.5°, 90° and 270°, 112.5° and 292.5°, and 157.5° and 337.5°. Internal guide holes 18 are also arranged along the column direction at the middle section of the gas production inner wellbore 15 at 45° and 225°, 90° and 270°, 135° and 315°, and 157.5° and 337.5°. Finally, internal guide holes 18 are arranged along the column direction at the lowermost section of the gas production inner wellbore 15 at 67.5° and 247.5°, 112.5° and 292.5°, and 135° and 315°. Inner guide holes 18 are arranged along the column direction at 157.5°, 157.5°, and 337.5°. The inner guide holes 18 and the outer guide holes 17 have the same diameter and are positioned accordingly. After assembling the gas production inner wellbore 15 and the fixed outer wellbore 16 together, ensure that the lower ends are flush and the starting scale lines of the rotation angle of the two wellbores are aligned. Rotate the gas production inner wellbore 15 clockwise sequentially by 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, 157.5°, and 180° to realize the process of simulating the development of the first, second, third, first-second, first-third, second-third, first-second-third, and no gas layer development in the gas reservoir.

[0078] The simulated gas reservoir multi-layer synergistic production device and experimental method of the present invention are implemented according to the following steps:

[0079] Step 1: According to the porosity of each layer in Table 1 and penetration rate Requirements: Prepare three types of artificial core basic experimental materials. The thickness of each of the three simulated gas layers is 3cm. Weigh 3kg of 400-mesh quartz sand for each layer. The cement content from top to bottom is 14%, 16%, and 18%, respectively. After mixing, spread them evenly into the mold.

[0080] Step 2: According to the actual sequence of each producing layer in the gas reservoir, the mixed base material is laid into the artificial core mold in sequence, from top to bottom as the first, second, and third simulated layers. For the multi-layer combined production wellbore 4, a rotary development wellbore is selected. The rotary development wellbore is vertically buried in the center of the base material, with its bottom in contact with the bottom of the mold. Then, a cover plate with a hole in the middle is added, so that the upper end of the rotary development wellbore passes through the round hole. The mold is moved into the pressurizing device to pressurize the cover plate to compact the artificial core base material, ensuring that the rotary development wellbore and the core material are in close contact, so that the gas does not flow along the well wall, and the guide holes on each section of the rotary development wellbore are located in the middle of the simulated gas layer being developed. After pressing, it is taken out and left to stand for 24 hours until it is completely solidified to obtain the physical model.

[0081] Step 3: Apply a layer of guar gum to the surface of the physical model and let it stand for 12 hours to dry, in order to prevent the epoxy used in subsequent processes from seeping into the physical model; then cast epoxy resin avoiding the rotary wellhead gas production joint 14, and make its surface completely covered with 1 cm thick epoxy resin without blocking the rotary wellhead gas production joint 14. After the epoxy resin has cured for 24 hours, the experimental model is obtained.

[0082] Step 4: Move the experimental model into the high-pressure chamber, and then connect the rotary development well gas extraction connector 14 to the external pressure gauge 5 and flow regulating valve 6 in sequence through the pipeline. Connect the flow regulating valve 6 to the flow meter, connect the flow meter to the high-pressure N2 gas cylinder, and close the flow regulating valve 6.

[0083] Step 5: Inject water into the internal voids of the high-pressure chamber through the external interface to apply confining pressure to the experimental model. P 围 Injection was stopped when the pressure reached 10 MPa.

[0084] Step 6: Open the flow regulating valve 6 and the high-pressure N2 gas cylinder. Rotate the gas extraction inner wellbore 15 clockwise by 157.5° so that the inner guide holes 18 of the three sections of the gas extraction inner wellbore 15 are aligned with the outer guide holes 17 of the three sections of the fixed outer wellbore 16. Inject gas into the model and adjust the flow regulating valve 6. When the pressure gauge 5 monitors the pressure... P p Stop charging when the pressure reaches 8.0 MPa, close the flow regulating valve 6, remove the high-pressure N2 gas cylinder, rotate the gas production inner wellbore 15 back to its normal position, and record the cumulative flow monitored by the gas flow meter. Q 1 is 247L;

[0085] Step 7: Rotate the inner wellbore 15 of the rotary development wellbore clockwise by 112.5° to simulate the development of the first and third simulated gas layers; slowly adjust the flow control valve 6 to simulate production at a rate of 400 mL / min. When the gas production flow rate is less than 10 mL / min, end the experiment and record the cumulative gas production. Q 2 is 234L, and all pressure is unloaded.

[0086] Example 3

[0087] Basically the same as Example 2, except that:

[0088] Step 6: Open the flow regulating valve 6 and the high-pressure N2 gas cylinder. Rotate the gas extraction inner wellbore 15 clockwise by 157.5° so that the inner guide holes 18 of the three sections of the gas extraction inner wellbore 15 are aligned with the outer guide holes 17 of the three sections of the fixed outer wellbore 16. Inject gas into the model and adjust the flow regulating valve 6. When the pressure gauge 5 monitors the pressure... P p Stop charging when the pressure reaches 8.3 MPa, close the flow regulating valve 6, remove the high-pressure N2 gas cylinder, rotate the gas extraction wellbore 15 back to its normal position, and record the cumulative flow rate monitored by the gas flow meter. Q 1 is 252L;

[0089] Step 7: Rotate the gas production inner wellbore 15 of the rotary development wellbore 90° clockwise to simulate the development of the first and second simulated gas layers; slowly adjust the flow control valve 6 to simulate production at a rate of 400 mL / min. When the pressure on pressure gauge 5 drops to 6 MPa, rotate the gas production inner wellbore 15 clockwise to a position of 112.5° and develop the first and third simulated gas layers at a rate of 400 mL / min. Finally, when the flow rate is less than 10 mL / min, end the experiment and record the cumulative gas production. Q 2 is 237L, and all pressure is unloaded.

Claims

1. A simulated multi-layer synergistic gas reservoir production experimental device, characterized in that, The system includes a gas storage unit, which is formed by stacking and pressing several simulated gas layers in sequence. A multi-layered combined wellbore (4) is installed at the center of the gas storage unit. A guide hole is opened on the outer periphery of the multi-layered combined wellbore (4). The multi-layered combined wellbore (4) is a composite development wellbore or a rotary development wellbore. One end of the multi-layered combined wellbore (4) is in contact with the bottom of the gas storage unit. The other end of the multi-layered combined wellbore (4) is located outside the gas storage unit and is provided with a gas extraction interface. The gas extraction interface is connected to a pressure gauge (5) and a flow regulating valve (6) in sequence through a pipeline. The flow regulating valve (6) is connected to an external gas source. A flow meter is connected between the flow regulating valve (6) and the external gas source. The multi-layer combined production wellbore (4) is a composite development wellbore, including several gas production wellbores closed at both ends. Each gas production wellbore is nested and fixed to each other, and the length of each gas production wellbore increases sequentially from the center at both ends from the outside to the inside. The number of gas production wellbores corresponds to the number of simulated gas layers. Each gas production wellbore has a gas production interface at its top. The lower section of each gas production wellbore corresponds to each simulated gas layer. The bottom end of the innermost gas production wellbore is in contact with the bottom of the bottommost simulated gas layer, and the bottom end of the outermost gas production wellbore is in contact with the bottom of the topmost simulated gas layer. Each lower section of each gas production wellbore corresponding to each simulated gas layer is symmetrically provided with several first guide holes (11). The multi-layer combined production wellbore (4) is a rotary development wellbore, including a hollow cylindrical gas production inner wellbore (15). The bottom end of the gas production inner wellbore (15) abuts against the bottom of the gas storage unit, and the top end of the gas production inner wellbore (15) is located outside the gas storage unit. The gas production inner wellbore (15) is fitted with a fixed outer wellbore (16), which is in close contact with the gas production inner wellbore (15). The bottom end of the fixed outer wellbore (16) is aligned with the bottom end of the gas production inner wellbore (15). The fixed outer wellbore (16) is a cylindrical structure. The length of the gas production inner wellbore (15) is greater than the length of the fixed outer wellbore (16). The gas production interface is located at the top of the gas production inner wellbore (15). Two rows of external guide holes (17) are symmetrically opened on the outer periphery of each section of the fixed outer wellbore (16) corresponding to each simulated gas layer, and the external guide holes (17) of each section are located in the same row facing upwards. The gas production wellbore (15) rotates at an angle α = 180° / ( ), where n is the number of simulated gas layers; The gas production wellbore (15) and each section of the outer periphery corresponding to each simulated gas layer are symmetrically provided with multiple rows of internal guide holes (18), and the internal guide holes (18) on each section are staggered or the same according to the rotation angle α and the mining requirements. The internal guide holes (18) are matched with the external guide holes (17).

2. The simulated gas reservoir multi-layer synergistic production experimental device according to claim 1, characterized in that, Each of the gas sampling interfaces is equipped with a connector.

3. The experimental apparatus for simulating multi-layer gas reservoir combined production according to claim 1, characterized in that, The external gas source is a high-pressure N2 gas cylinder.

4. A simulated multi-layer synergistic gas reservoir production test method, characterized in that, Using the simulated gas reservoir multi-layer synergistic production experimental apparatus as described in any one of claims 1-3, the steps are as follows: Step 1. Determine the experimental parameters based on the actual sequence and thickness of each producing layer in the gas reservoir; Step 2. Prepare each simulated gas layer and multi-layer combined wellbore (4) according to the experimental parameters and press them into shape; Step 3. Apply adhesive to the surface of the pressed physical model and cast it with epoxy resin to obtain the experimental model; Step 4. Place the experimental model in the high-pressure container, and connect the external pressure gauge (5), flow regulating valve (6), flow meter and external gas source to each gas sampling port in sequence; apply pressure, and stop applying pressure when the confining pressure rises to the actual pressure; Step 5. Open the external gas source and flow regulating valve (6), fill with gas, regulate the flow regulating valve (6) and the multi-layer combined wellbore (4), when the pressure of each pressure gauge (5) is 1.5~2.0MPa lower than the confining pressure, close the flow regulating valve (6), remove the external gas source, and record the cumulative flow. Step 6. Open the flow regulating valve (6) and carry out gas storage and extraction according to development needs; when the gas extraction flow rate is less than 10 mL / min, calculate the cumulative gas extraction volume and end the experiment.

5. The experimental method for simulating multi-layer synergistic gas production in a gas reservoir according to claim 4, characterized in that, In step 1, the experimental parameters include the number of each simulated gas layer, the thickness and physical properties of each simulated gas layer, and the type and quality of the artificial rock core base material required for each simulated layer.

6. The experimental method for simulating multi-layer synergistic gas production in a gas reservoir according to claim 5, characterized in that, Step 2 specifically involves determining the type and quality of artificial core base materials required for each simulated gas layer based on experimental parameters. After weighing each base material, the base materials of the same layer are mixed evenly and reserved. The mixed base materials are laid into the artificial core mold in sequence according to the actual order of each production layer of the gas reservoir. The type, height and position of the multi-layer combined production wellbore (4) are determined. After the multi-layer combined production wellbore (4) is assembled, it is vertically buried in the center of the base material, with the bottom in contact with the bottom of the mold. The mold is then moved into the pressurizing device, and a cover plate with a hole in the middle is added. The upper end of the multi-layer combined production wellbore (4) passes through the round hole. The cover plate is pressurized to compact the artificial core base material. After pressing, it is taken out of the mold and left to stand until it is completely solidified to obtain the physical model. In step 4, the pressure application specifically involves injecting a physicochemically stable liquid into the internal pores of the high-pressure vessel through the external interface to apply confining pressure to the experimental model, and monitoring the confining pressure through the pressure gauge on the high-pressure vessel. Liquid injection is stopped when the confining pressure rises to the actual reservoir pressure.

7. The experimental method for simulating multi-layer synergistic gas production in a gas reservoir according to claim 6, characterized in that, In step 6, the specific steps of gas storage and extraction based on development needs are as follows: When the multi-layer combined wellbore (4) is a composite development wellbore, a flow meter is connected after each flow regulating valve (6). According to the development needs, the flow regulating valve (6) corresponding to the simulated gas layer to be developed is opened, and the multi-layer combined wellbore (4) and the flow regulating valve (6) are adjusted to carry out gas storage and extraction. When the multi-layer commingled wellbore (4) is a rotary development wellbore, the multi-layer commingled wellbore (4) is rotated clockwise to the corresponding angle according to the development needs for gas storage and extraction.

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