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

Abstract

The simulation gas reservoir multi-layer commingling production experimental device comprises a gas storage unit, the gas storage unit is formed by sequentially aligning, stacking and pressing a plurality of simulation gas layers, a multi-layer commingling production shaft is arranged at the center position in the gas storage unit in a penetrating mode, the bottoms of the simulation gas layers are aligned, and a gas production connector is arranged at the top end of the multi-layer commingling production shaft. The gas production interface is sequentially connected with a pressure gauge and a flow regulating valve through a pipeline, and the flow regulating valve is communicated with an external gas source; the experimental method comprises the following steps: selecting a simulated gas layer material and a shaft, carrying out compression molding, gluing, pouring epoxy resin, applying pressure, filling gas, and carrying out gas storage exploitation according to requirements. According to the simulation gas reservoir multi-layer commingling production experimental device and experimental method, the number of used equipment is small, application of multiple development schemes can be achieved on the same model, diagenesis materials are pressed and formed, two adjacent simulation gas layers are solidified together, and in the development process, the internal pressure profile of the model is continuously distributed; operation is simple and flexible, and cost and time are saved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas reservoir recovery, and in particular relates to a simulated gas reservoir multi-layer combined production experimental device, and also relates to a simulated gas reservoir multi-layer combined production experimental method. Background Art

[0002] For gas reservoirs with multiple production layers, the differences in pressure, temperature, and fluid properties during the accumulation process lead to significant differences in the porosity, permeability, water saturation and other characteristics of each production layer, which in turn leads to different production capacities of each layer. For reservoirs with higher production capacities, the rapid production of natural gas leads to rapid exhaustion of formation energy, making it difficult to carry out subsequent production increase and transformation operations. For reservoirs with lower production capacities, the economic benefits are poor and it is difficult to achieve the production increase target. If the same wellbore is used to develop such gas reservoirs, it is impossible to obtain the production dynamic data of a single gas layer, nor can it be guaranteed that the production system used is suitable for each reservoir, resulting in uneven utilization of gas reservoir reserves.

[0003] Multi-layer commingled production is an important technical means to achieve efficient and economical development of gas reservoir reserves. On the one hand, the development of multiple production layers with relatively independent seepage channels ensures efficient development of gas reservoirs without inter-layer interference; on the other hand, multi-layer commingled production technology can control a single production layer and achieve balanced development of reserves in each layer by controlling its production pressure difference.

[0004] At present, most scholars use the method of connecting multiple core clamps in parallel to simulate the multi-layer production process of gas reservoirs. However, this method ignores the problem that a single reservoir cannot be developed with a single well during the actual multi-layer production process of gas reservoirs. In addition, the clamps completely isolate multiple simulated gas layers, and the pressure profile is discontinuous in the vertical direction. It is difficult to determine the pressure field of the actual gas reservoir based on such experimental results, and the reserve utilization of each production layer is not accurately judged. Summary of the invention

[0005] The purpose of the present invention is to provide a simulated gas reservoir multi-layer combined production experimental device, which can develop multiple simulated gas layers with a single gas well and can flexibly adjust the developed layer combination and production speed.

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

[0007] The technical solution adopted in the present invention is to provide a multi-layer combined production experimental device for simulating gas reservoirs, including a gas storage unit. The gas storage unit is formed by a number of simulated gas layers that are aligned, stacked and pressed in sequence. A multi-layer combined production wellbore is penetrated at the center position of the gas storage unit. A diversion hole is opened on the outer periphery of the multi-layer combined production wellbore. The multi-layer combined production wellbore is a composite development wellbore or a rotary development wellbore. One end of the multi-layer combined production wellbore is abutted against the bottom of the gas storage unit, and the other end of the multi-layer combined 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 present invention is also characterized in that:

[0009] The multi-layer combined production wellbore is a composite development wellbore, including several gas production wellbores with closed ends. The gas production wellbores are mutually socketed and fixed, and the lengths of the gas production wellbores increase successively 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. A gas production interface is respectively arranged at the top of each gas production wellbore, and 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 the bottom of the topmost simulated gas layer; a number of first diversion holes are symmetrically opened in the lower section of each gas production wellbore corresponding to each simulated gas layer.

[0010] The multi-layer combined production wellbore is a rotary development wellbore, including a gas production inner wellbore of a hollow cylindrical structure, the bottom end of the gas production inner wellbore abuts against 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 provided with a gas production interface;

[0011] The fixed outer wellbore is connected to the gas production inner wellbore, the fixed outer wellbore is closely fitted with the gas production inner wellbore, and the bottom end of the fixed outer wellbore is aligned with the bottom end of the gas production inner wellbore; the fixed outer wellbore is a cylindrical structure, and the length of the gas production inner wellbore is greater than that of the fixed outer wellbore;

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

[0013] The rotation angle of the wellbore in gas production Multiple rows of inner diversion holes are symmetrically opened on the outer periphery of each section of the gas production wellbore corresponding to each simulated gas layer, and the inner diversion holes on each section are staggered or the same in row according to the rotation angle α and the production requirements, and the inner diversion holes are matched with the outer diversion holes.

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

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

[0016] Another technical solution adopted by the present invention is to simulate a multi-layer commingled production experimental method of a gas reservoir, using the above-mentioned simulated gas reservoir multi-layer commingled production experimental device, and the specific steps are as follows:

[0017] Step 1. Determine the experimental parameters according to the actual sequence and thickness of each production layer in the gas reservoir;

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

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

[0020] Step 4. Place the experimental model in a high-pressure container, and connect each gas collection interface to an external pressure gauge, a flow control valve, a flow meter, and an 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 the gas, adjust the flow control valve and the multi-layer combined production wellbore, and when the pressure of each pressure gauge is 1.5-2.0MPa lower than the confining pressure, close the flow control valve to remove the external gas source and record the accumulated flow;

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

[0023] Another technical solution of the present invention is also characterized in that:

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

[0025] Step 2 specifically includes: determining the type and quality of the artificial core base material required for each simulated gas layer according to the experimental parameters; weighing each base material, mixing the base materials of the same layer evenly and retaining them; placing the mixed base materials into the artificial core mold in sequence according to the actual order of each production layer of the gas reservoir; determining the type, height and diversion hole position of the multi-layer combined production wellbore; burying the multi-layer combined production wellbore vertically in the center of the base material after assembly, with the bottom in contact with the bottom of the mold; moving the mold into the pressurizing device, adding a cover plate with a hole in the middle, passing a circular hole through the upper end of the multi-layer combined production wellbore, pressurizing the cover plate to compact the artificial core base material; taking it out from the mold after the pressing is completed and letting it stand until it is completely solidified to obtain a physical model;

[0026] In step 4, the pressure application is specifically as follows: a liquid with stable physical and chemical properties is injected into the internal space of the high-pressure container through the external interface to apply confining pressure to the experimental model, and the confining pressure is monitored by the pressure gauge provided by the high-pressure container. When the confining pressure rises to the actual reservoir pressure, the liquid injection is stopped.

[0027] In step 6, gas storage exploitation is carried out according to development needs as follows:

[0028] When the multi-layer commingled production wellbore is a composite development wellbore, flow meters are connected after each flow regulating valve, and the flow regulating valve corresponding to the simulated gas layer to be developed is opened according to development needs, and the multi-layer commingled production wellbore and flow regulating valve are adjusted to carry out gas storage and production;

[0029] When the multi-layer combined production wellbore is a rotary development wellbore, the development wellbore is rotated clockwise to the corresponding angle according to development needs to carry out gas storage and production.

[0030] The beneficial effects of the present invention are:

[0031] 1) Artificial core technology is used to combine multiple simulated gas layers according to the actual stratigraphic sequence, so that the pressure field between each layer is continuously distributed. Combined with the actual mine field, multiple simulated gas layers can be developed with a single gas well, and the developed layer combination and mining speed can be flexibly adjusted; the switch or production pressure difference of a single production layer can be controlled during the development process, so that the simulation experiment carried out is more in line with engineering reality;

[0032] 2) By pressing the diagenetic material into shape once, two adjacent simulated gas layers are consolidated together without a separator 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 combined production of gas reservoirs by connecting multiple core holders in parallel, the present invention uses less equipment, can implement the application of multiple development schemes on the same model, is simple and flexible to operate, and saves experimental costs and time costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a multi-layer combined production experimental device for simulating gas reservoirs according to the present invention;

[0035] Figure 2 It is a structural schematic diagram of a composite development wellbore of a multi-layer combined production experimental device for simulating gas reservoirs according to the present invention;

[0036] Figure 3 It is a structural schematic diagram of a rotary development wellbore of a multi-layer combined production experimental device for simulating gas reservoirs according to the present invention.

[0037] In the figure, 1. the first simulated gas layer, 2. the second simulated gas layer, 3. the third simulated gas layer, 4. the multi-layer combined production wellbore, 5. the pressure gauge, 6. the flow regulating valve, 7. the third simulated layer gas production interface, 8. the second simulated layer gas production interface, 9. the first simulated layer gas production interface, 10. the first simulated layer gas production wellbore, 11. the first diversion hole, 12. the second simulated layer gas production wellbore, 13. the third simulated layer gas production wellbore; 14. the rotary development wellbore gas production interface, 15. the inner gas production wellbore, 16. the fixed outer wellbore, 17. the outer diversion hole, 18. the inner diversion hole. DETAILED DESCRIPTION

[0038] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] The simulated gas reservoir multi-layer combined production experimental device of the present invention has a structure as follows Figure 1 As shown, it includes a gas storage unit, which is formed by stacking and pressing multiple simulated gas layers arranged laterally. The sequence of the simulated gas layers is based on the sequence of the actual reservoir. The thickness of the simulated gas layers is controlled by controlling the added mass of the diagenetic material and the molding sequence. A section of the multi-layer combined production wellbore 4 is located outside the gas storage unit, and another section is inserted into the center of the gas storage unit. The bottom end of the multi-layer combined production wellbore 4 abuts against the bottom of the bottom simulated gas layer. The top of the multi-layer combined production wellbore 4 is provided with a gas production interface equipped with a joint for connecting other pipelines. The joint is connected to a pressure gauge 5 and a flow regulating valve 6 in sequence through a pipeline for monitoring the internal pressure of the device and output flow control. The flow regulating valve 6 is connected to an external gas source, which is a high-pressure N2 gas cylinder for inflating the inside of the model.

[0040] There are two types of multi-layer combined production wellbore 4: composite development wellbore and rotary development wellbore. They can be easily selected according to mining needs, but it must be ensured that the bottom of the multi-layer combined production wellbore 4 is flush with the lower boundary of the lowest simulated gas layer, and the top diversion holes of the multi-layer combined production wellbore 4 are completely covered by the uppermost simulated gas layer; during the experiment, all gas production interfaces of the multi-layer combined production wellbore 4 must be connected to the pressure gauge 5 and the flow regulating valve 6 in sequence for monitoring the internal pressure of the device and output flow control.

[0041] Composite development wellbore structure Figure 2As shown, it includes a number of gas production wellbores with closed ends, and the gas production wellbores are mutually sleeved and fixed in the form of concentric circles. From the outside to the inside, the lengths of the gas production wellbores along the center from both ends increase successively, and the internal gases of adjacent wellbores are isolated by the well wall. A gas production interface is provided at the top of each gas production wellbores. The number of gas production wellbores and the number of gas production interfaces are consistent with the number of simulated gas layers. Each gas production interface is equipped with a joint, and each joint is connected to a pressure gauge 5 and a flow regulating valve 6 in sequence through a pipeline for monitoring the internal pressure of the device and controlling the output flow. Each 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, and the external gas source is a high-pressure N2 gas cylinder.

[0042] The length of each lower section of the gas wellbore corresponds to the thickness of each simulated gas layer. Each lower section of the gas wellbore corresponds to a simulated gas layer. The bottom end of the innermost gas wellbore contacts the bottom of the bottommost simulated gas layer, and the bottom end of the outermost gas wellbore abuts the bottom of the topmost simulated gas layer. The lower sections of each gas wellbore corresponding to each simulated gas layer are symmetrically provided with a number of first flow guide holes 11, and the number and diameter of the flow guide holes are set according to specific experimental requirements. Each gas wellbore has no other fluid channels except the flow guide holes and the gas production interface. The gas enters the gas wellbore through the first flow guide holes 11 in the lower section of the gas wellbore, and then flows out from the gas production interface at the top of the gas wellbore. When in use, the flow control valve 6 connected to the gas production joint is adjusted to adjust the production speed of a single or multiple gas layers.

[0043] The structure of the rotary development wellbore is shown in Figure 3, which includes a gas production inner wellbore 15 of a hollow cylindrical structure, the bottom end of the gas production inner wellbore 15 is abutted against the bottom of the gas storage unit, and the top of the gas production inner wellbore 15 is located outside the gas storage unit; the gas production inner wellbore 15 is outer-connected with a fixed outer wellbore 16, the fixed outer wellbore 16 is tightly fitted with the gas production inner wellbore 15, the fixed outer wellbore 16 is a cylindrical structure, and the bottom end of the fixed outer wellbore 16 is aligned with the bottom end of the gas production inner wellbore 15; the length of the gas production inner wellbore 15 is greater than that of the fixed outer wellbore 16, the rotary development wellbore gas production joint 14 is located at the top of the gas production inner wellbore 15, and the rotary development wellbore gas production joint 14 is equipped with The joint is connected to a pressure gauge 5 and a flow regulating valve 6 in sequence through a pipeline, which are used to monitor the internal pressure of the device and control the output flow. 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, and two rows of external flow guide holes 17 are symmetrically opened on each section of the outer periphery corresponding to the fixed outer wellbore 16 and each simulated gas layer, and the external flow guide holes 17 of each section are located in the same row upward, and the number and diameter of the external flow guide holes 17 are set according to specific experimental requirements; the size of the internal flow guide holes 18 of each section is the same as that of the external flow guide holes 17, and they can all be rotated to overlap with the external flow guide holes 17. After the gas production inner wellbore 15 is rotated at different angles, the combined development of single-layer or multi-layer simulated gas layers can be realized.

[0044] After assembling the inner wellbore 15 and the fixed outer wellbore 16 together, ensure that the lower ends are flush and the scale lines of the rotation angle starting points of the two wellbores are aligned. Where n is the number of simulated air layers, is the sum of the number of development plans, 1 is the case of not developing the gas layer, which is used to close the model gas production, It indicates the number of development plans for selecting one layer for mining from a model with n simulated gas layers. Indicates the number of development plans for selecting 2 layers for exploitation from the model of n simulated gas layers, and so on, until all n simulated layers are exploited. Several development plans can also be selected for exploitation according to actual needs; multiple rows of inner flow guide holes 18 are symmetrically opened on each section of the outer periphery corresponding to each simulated gas layer in the gas production inner wellbore 15, and the inner flow guide holes 18 on each section are staggered or the same according to the rotation angle α and the exploitation requirements, that is, after the gas production inner wellbore 15 rotates α, a group of inner flow guide holes 18 are symmetrically arranged along the axis on the wall of the gas production inner wellbore 15 to realize a development plan, and after rotating α again, another group of inner flow guide holes 18 are symmetrically arranged along the axis on the wall of the gas production inner wellbore 15 to realize another development plan, until all the inner flow guide holes 18 of the development plan are arranged. By rotating the gas production inner wellbore 15, the inner flow guide holes 18 corresponding to each development plan are aligned with the outer flow guide holes 17 of the fixed outer wellbore 16, thereby realizing the permutation and combination exploitation of the simulated gas layer.

[0045] The working principle of the simulated gas reservoir multi-layer combined production device of the present invention is: relying on the close contact between the simulated gas layer and the outer wall of the wellbore to prevent gas flow between the simulated gas layers, and the gas can only flow through the wellbore diversion holes, and then constructing an independent fluid flow channel for separate or combined production of each simulated gas layer. By controlling the flow rate at the outlet of each flow channel, single-layer or multi-layer development of the gas layer is achieved. Less equipment is used, and multiple development plans can be applied on the same model. The operation is simple and flexible, saving experimental costs and time costs.

[0046] The experimental method for simulating multi-layer commingled production of gas reservoirs of the present invention adopts the experimental device for simulating multi-layer commingled production of gas reservoirs described above, and is specifically implemented according to the following steps:

[0047] Step 1: Determine the experimental parameters according to the actual sequence and thickness of each production layer in the gas reservoir;

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

[0049] Step 2, determine the type and quality of the artificial core base material required for each simulated gas layer according to the experimental parameters, weigh each base material, mix the base materials of the same layer evenly and retain them, and lay the mixed base materials into the artificial core mold in sequence according to the actual order of each production layer of the gas reservoir, determine the type, height and diversion hole position of the multi-layer combined production wellbore 4, and bury the multi-layer combined production wellbore 4 vertically in the center of the base material after assembly, with the bottom in contact with the bottom of the mold, and move the mold into the pressurizing device, cover it with a cover plate with a hole in the middle, and pass the circular hole through the upper end of the multi-layer combined production wellbore 4, pressurize the cover plate to compact the artificial core base material, ensure 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 make the diversion holes of each section on the multi-layer combined production wellbore 4 located in the middle of the developed simulated gas layer, and take it out from the mold after the pressing is completed and let it stand until it is completely solidified to obtain a physical model;

[0050] Step 3: Apply a layer of guar gum on the surface of the physical model and let it stand to dry to prevent the epoxy used in the subsequent process from penetrating into the physical model; then, epoxy resin is cast avoiding each gas sampling interface so that the surface is completely covered with epoxy resin, and 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 with the external pressure gauge 5 and the flow regulating valve 6 in sequence through the pipeline, and then connect each flow regulating valve 6 to the same flow meter, and the flow meter is connected to the high-pressure N2 gas cylinder, and all flow regulating valves 6 are closed;

[0052] A liquid with stable physical and chemical properties is injected into the internal space of the high-pressure vessel through the external interface to apply a confining pressure P to the experimental model. 围 The surrounding pressure is monitored by the pressure gauge of the high-pressure vessel. 围 Stop injection when the actual reservoir pressure is reached;

[0053] Step 5: Open the high-pressure N2 gas cylinder and the flow regulating valve 6, fill the experimental model with gas, align the diversion holes of each wellbore of the multi-layer combined production wellbore 4, and adjust the flow regulating valve 6 so that the pressure P of each pressure gauge 5 p Rise synchronously until each pressure P p Confining pressure P 围 When the pressure drops to 1.5-2.0 MPa, stop filling, close the flow regulating valve 6 or rotate the inner wellbore 15 to the fully closed position, record the accumulated 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 production according to development needs; when the gas production flow rate is less than 10mL / min, record the cumulative readings of each flow meter, sum them up to obtain the cumulative gas production volume Q2, and end the experiment.

[0055] In step 6, gas storage exploitation is carried out according to development needs as follows:

[0056] When the multi-layer commingled production wellbore 4 is a composite development wellbore, flow meters are connected after each flow regulating valve 6, and the flow regulating valve 6 corresponding to the simulated gas layer to be developed is opened according to development needs, and the multi-layer commingled production wellbore 4 and the flow regulating valve 6 are adjusted to perform gas storage and production;

[0057] When the multi-layer combined production wellbore 4 is a rotary development wellbore, the gas production inner wellbore 15 of the rotary development wellbore is rotated clockwise to a corresponding angle according to development requirements to carry out gas storage production.

[0058] The advantages of the simulated gas reservoir multi-layer combined production experimental method of the present invention are that 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, and combined with the actual situation of the mine, a simulated gas well is used to realize the joint development of multiple production layers, and the switch or production pressure difference of a single production layer can be controlled during the development process, so that the simulation experiment carried out is more in line with engineering reality; by using a method of once-pressing the diagenetic material to consolidate two adjacent simulated gas layers together, without a partition device in between, the pressure profile inside the model is continuously distributed during the development process.

[0059] Example 1

[0060] The simulated gas reservoir multi-layer combined production experimental device of the present invention has a structure as follows 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. The three simulated gas layers are all arranged horizontally. The multi-layer combined production wellbore 4 is a composite development wellbore, including a first simulated layer gas production wellbore 10, a second simulated layer gas production wellbore 12, and a third simulated layer gas production wellbore 13, which respectively correspond to the production of each simulated gas layer. The three gas production wellbores are closed at both ends, and each gas production wellbore is fixed to each other in the form of concentric circles. From the outside to the inside, the length of each gas production wellbore increases from the center from both ends in sequence. The third simulated layer gas production wellbore 13 is the longest, and the first simulated layer gas production wellbore 10 is the shortest. The gases inside adjacent wellbores are isolated by the well walls.

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

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

[0063] A first simulated layer gas production interface 9 is provided at the top of the first simulated layer gas production wellbore 10, and the first simulated layer gas production interface 9 is connected to a pressure gauge 5 and a flow regulating valve 6. The length of the lower section of the first simulated layer gas production wellbore 10 is the same 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 a position of the first simulated layer gas production wellbore 10 corresponding to the first simulated gas layer 1.

[0064] The three gas production wells correspond to the production of three simulated layers respectively, and the three flow regulating valves 6 are connected to the high-pressure N2 gas cylinder; a flow meter is connected between the flow regulating valve 6 and the high-pressure N2 gas cylinder. The gas enters the gas production well through the diversion hole in the lower section of the gas production well, and then flows out from the gas production interface at the top of the gas production well. When in use, the flow regulating valve 6 connected to the gas production joint is adjusted to adjust the production speed of a single or multiple gas layers.

[0065] The experimental method for simulating multi-layer commingled production of gas reservoirs of the present invention has the following specific implementation steps:

[0066] Step 1: According to the porosity of each layer in Table 1 below and permeability K i Requirements: Prepare three kinds of artificial core basic experimental materials. The thickness of the three simulated gas layers is 3 cm. Weigh 3 kg of 400 mesh quartz sand for each layer. The cementing content is 14%, 16%, and 18% from top to bottom. After mixing, lay them flat into the mold in sequence.

[0067] Table 1 Porosity and permeability requirements for each simulated layer

[0068]

[0069] Step 2: according to the actual order of each production layer of the gas reservoir, the mixed basic materials are laid into the artificial core mold in sequence, from top to bottom, they are the first, second and third simulation layers, and the multi-layer combined production wellbore 4 selects a composite development wellbore, and the composite development wellbore is vertically buried in the center of the basic material, with its bottom in contact with the bottom of the mold, and then covered with a cover plate with a hole in the middle, so that the upper end of the composite development wellbore passes through the circular hole; the arranged mold is moved into the pressurizing device, and the cover plate is pressurized to compact the artificial core basic material, ensuring that the composite development wellbore is in close contact with the core material, so that the gas does not flow along the well wall, and each section of the diversion hole on the composite development wellbore is located in the middle of the simulated gas layer to be developed. After the pressing is completed, it is taken out and left to stand for 24 hours until it is completely solidified to obtain a physical model;

[0070] Step 3: Apply a layer of guar gum on the surface of the physical model and let it stand for 12 hours to dry, so as to prevent the epoxy used in the subsequent process from penetrating into the physical model; then, cast the epoxy resin avoiding each gas collection interface, and on the basis of not blocking each gas collection interface, make the surface completely covered with 1 cm thick epoxy resin, and let it stand for 24 hours until the epoxy resin is cured, and then obtain the experimental model;

[0071] Step 4, move the experimental model into the high-pressure pressure chamber, and then connect each gas sampling interface with the external pressure gauge 5 and the flow regulating valve 6 in sequence through the pipeline, 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 the flow regulating valves 6;

[0072] Step 5: Inject water into the internal space of the high-pressure pressure chamber through the external interface to apply a confining pressure P to the experimental model. Stop the injection when the confining 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 gauge 5 connected to each gas sampling interface rises synchronously, and stop filling until each pressure Pp reaches 8.5MPa, 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 behind each flow regulating valve 6, open the flow regulating valve 6 of the first simulated layer gas production wellbore 10 and the third simulated layer gas production wellbore 13; slowly adjust the flow regulating valve 6 to simulate production at a production rate of 400mL / min. When the gas production flow rate is less than 10mL / min, end the experiment, record the cumulative gas production Q2 as 243L, and unload all pressures.

[0075] Example 2

[0076] The simulated gas reservoir multi-layer combined production experimental device of the present invention has a structure as follows Figure 1 and Figure 3As 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, and the three simulated gas layers are all arranged horizontally. The multi-layer combined production wellbore 4 is a rotary development wellbore, including a gas production inner wellbore 15 with a hollow cylindrical structure, the bottom end of the gas production inner wellbore 15 abuts against the bottom of the gas storage unit, and the top of the gas production inner wellbore 15 is located outside the gas storage unit; the gas production inner wellbore 15 is connected with a fixed outer wellbore 16, and the gas production inner wellbore 15 is a metal cylinder with an upper and lower bottom surfaces, the outer diameter of which is slightly smaller than the inner diameter of the fixed outer wellbore 16. The fixed outer wellbore 16 is tightly fitted with the gas production inner wellbore 15. The fixed outer wellbore 16 is a metal cylinder without bottom surfaces. The bottom end of the fixed outer wellbore 16 is aligned with the bottom end of the gas production inner wellbore 15. The rotary development wellbore gas production joint 14 is located at the top of the gas production inner wellbore 15. The rotary development wellbore gas production joint 14 is equipped with a joint. The joint is connected to a pressure gauge 5 and a flow regulating valve 6 in sequence through a pipeline for monitoring the internal pressure of the device and output flow control. 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 height of the fixed outer wellbore 16 is 9 cm, the length of the gas production inner wellbore 15 is greater than the length of the fixed outer wellbore 16, two rows of outer guide holes 17 are symmetrically arranged at the heights of the fixed outer wellbore 16 at 0-3 cm, 3-6 cm, and 6-9 cm, respectively, and the outer guide holes 17 of each section are located in the same row upward. When n is 3, the gas production inner wellbore 15 rotates by an angle of The inner guide holes 18 are arranged in a row direction at 22.5° and 202.5°, 90° and 270°, 112.5° and 292.5°, 157.5° and 337.5° in the uppermost section of the gas production inner wellbore 15; the inner guide holes 18 are arranged in a row direction at 45° and 225°, 90° and 270°, 135° and 315°, 157.5° and 337.5° in the middle section of the gas production inner wellbore 15; and the inner guide holes 18 are arranged in a row direction at 67.5° and 247.5°, 112.5° and 292.5°, 135° and 315°, 157.5° and 337.5° in the lowermost section of the gas production inner wellbore 15 Inner guide holes 18 are arranged at 7.5° and 337.5° along the column direction; the inner guide holes 18 and the outer guide holes 17 have the same diameter and corresponding positions; after the gas production inner wellbore 15 and the fixed outer wellbore 16 are assembled together, the lower ends are ensured to be flush, and the scale lines of the starting points of the rotation angles of the two wellbores are aligned, so that the gas production inner wellbore 15 is rotated clockwise by 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, 157.5°, and 180° in sequence to realize the process of simulating the development of the first, second, third, one-two, one-three, two-three, one-two-three, and no development of gas layers in the gas reservoir.

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

[0079] Step 1: According to the porosity of each layer in Table 1 and permeability K i Requirements: Prepare three kinds of artificial core basic experimental materials. The thickness of the three simulated gas layers is 3 cm. Weigh 3 kg of 400 mesh quartz sand for each layer. The cementing content is 14%, 16%, and 18% from top to bottom. After mixing, lay them flat into the mold in sequence.

[0080] Step 2: according to the actual order of each production layer of the gas reservoir, the mixed basic materials are laid into the artificial core mold in sequence, from top to bottom, they are the first, second and third simulation layers, and the multi-layer combined production wellbore 4 selects a rotary development wellbore, and the rotary development wellbore is vertically buried in the center of the basic material, with its bottom in contact with the bottom of the mold, and then covered with a cover plate with a hole in the middle, so that the upper end of the rotary development wellbore passes through the circular hole; the arranged mold is moved into the pressurizing device, and the cover plate is pressurized to compact the artificial core basic material, ensuring that the rotary development wellbore is in close contact with the core material, so that the gas does not flow along the well wall, and the diversion holes of each section on the rotary development wellbore are located in the middle of the simulated gas layer to be developed. After the pressing is completed, it is taken out and left to stand for 24 hours until it is completely solidified to obtain a physical model;

[0081] Step 3: Apply a layer of guar gum on the surface of the physical model and let it stand for 12 hours to dry, so as to prevent the epoxy used in the subsequent process from penetrating into the physical model; then, avoid the rotary development wellbore gas production joint 14 and cast the epoxy resin, so that the surface is completely covered with 1 cm thick epoxy resin without blocking the rotary development wellbore gas production joint 14, and let the epoxy resin stand for 24 hours to cure, and then obtain the experimental model;

[0082] Step 4, move the experimental model into the high-pressure pressure chamber, and then connect the rotary development wellbore gas production joint 14 to the external pressure gauge 5 and the 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 space of the high-pressure pressure chamber through the external interface to apply confining pressure P to the experimental model. 围 Stop injection when the pressure reaches 10MPa;

[0084] Step 6, open the flow regulating valve 6 and the high-pressure N2 gas cylinder, rotate the inner gas wellbore 15 clockwise by 157.5°, align the inner flow guide holes 18 of the three sections of the inner gas wellbore 15 with the outer flow guide holes 17 of the three sections of the fixed outer wellbore 16, fill the model with gas, adjust the flow regulating valve 6, and when the pressure gauge 5 monitors the pressure P p When the pressure reaches 8.0 MPa, stop filling, close the flow regulating valve 6, remove the high-pressure N2 gas cylinder, rotate the gas production wellbore 15 to the right position, and record the cumulative flow Q1 monitored by the gas flow meter as 247 L;

[0085] Step 7, rotate the gas production inner wellbore 15 of the rotary development wellbore 112.5° clockwise 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 400mL / min. When the gas production flow rate is less than 10mL / min, end the experiment, record the cumulative gas production Q2 as 234L, and unload all pressures.

[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 inner gas wellbore 15 clockwise by 157.5°, align the inner flow guide holes 18 of the three sections of the inner gas wellbore 15 with the outer flow guide holes 17 of the three sections of the fixed outer wellbore 16, fill the model with gas, adjust the flow regulating valve 6, and when the pressure gauge 5 monitors the pressure P p When the pressure reaches 8.3 MPa, stop filling, close the flow regulating valve 6, remove the high-pressure N2 gas cylinder, rotate the gas production inner wellbore 15 to the right position, and record the cumulative flow Q1 monitored by the gas flow meter as 252 L;

[0089] Step 7. Rotate the inner wellbore 15 of the rotary development wellbore by 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 of the pressure gauge 5 drops to 6 MPa, rotate the inner wellbore 15 clockwise to 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, record the cumulative gas production Q2 as 237 L, and unload all pressures.

Claims

1. A simulated gas reservoir multi-layer combined production experimental device, characterized in that: The invention comprises a gas storage unit, wherein the gas storage unit is formed by a plurality of simulated gas layers being aligned, stacked and pressed in sequence, a multi-layer combined production wellbore (4) is penetrated at the center position of the gas storage unit, a flow guide hole is opened on the outer periphery of the multi-layer combined production wellbore (4), the multi-layer combined production wellbore (4) is a composite development wellbore or a rotary development wellbore, one end of the multi-layer combined production wellbore (4) is in contact with the bottom of the gas storage unit, the other end of the multi-layer combined production wellbore (4) 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 (5) and a flow regulating valve (6) in sequence through a pipeline, the flow regulating valve (6) is connected to an external gas source, and a flow meter is connected between the flow regulating valve (6) and the external gas source.

2. The simulated gas reservoir multi-layer commingled production experimental device according to claim 1 is characterized in that: The multi-layer combined production wellbore (4) is a composite development wellbore, including a plurality of gas production wellbores with closed ends, each of which is mutually sleeved and fixed, and the lengths of each gas production wellbore are increased from the center from the outside to the inside. The number of gas production wellbores corresponds to the number of simulated gas layers. The top of each gas production wellbore is respectively provided with a gas production interface, and 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 the bottom of the topmost simulated gas layer; the lower section of each gas production wellbore corresponding to each simulated gas layer is symmetrically provided with a plurality of first guide holes (11).

3. The simulated gas reservoir multi-layer commingled production experimental device according to claim 1 is characterized in that: The multi-layer combined production wellbore (4) is a rotary development wellbore, comprising a gas production inner wellbore (15) of a hollow cylindrical structure, 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 inner gas extraction wellbore (15) is connected with a fixed outer wellbore (16) on the outside, the fixed outer wellbore (16) is tightly fitted with the inner gas extraction wellbore (15), and the bottom end of the fixed outer wellbore (16) is aligned with the bottom end of the inner gas extraction wellbore (15); the fixed outer wellbore (16) is a cylindrical structure, the length of the inner gas extraction wellbore (15) is greater than the length of the fixed outer wellbore (16), and the gas extraction interface is located at the top of the inner gas extraction wellbore (15); two rows of external flow guide holes (17) are symmetrically opened on each section of the outer periphery of the fixed outer wellbore (16) corresponding to each simulated gas layer, and the external flow guide holes (17) of each section are located in the same row and face upward.

4. The simulated gas reservoir multi-layer commingled production experimental device according to claim 3 is characterized in that: The gas production inner wellbore (15) rotates each time by an angle Where n is the number of simulated air layers; The gas production inner wellbore (15) and each section of the outer periphery corresponding to each simulated gas layer are symmetrically provided with multiple rows of inner flow guide holes (18), and the inner flow guide holes (18) on each section are staggered or identical in row direction according to the rotation angle α and production requirements, and the inner flow guide holes (18) match the outer flow guide holes (17).

5. The simulated gas reservoir multi-layer commingled production experimental device according to claim 1 is characterized in that: Each of the gas collection interfaces is equipped with a joint.

6. The simulated gas reservoir multi-layer commingled production experimental device according to claim 1, characterized in that: The external gas source is a high-pressure N2 gas cylinder.

7. The experimental method of the simulated gas reservoir multi-layer combined production experimental device according to any one of claims 1 to 6, characterized in that: The steps are as follows: Step 1. Determine the experimental parameters according to the actual sequence and thickness of each production layer in the gas reservoir; Step 2. Prepare each simulated gas layer and multi-layer combined production wellbore (4) according to the experimental parameters and press them into shape; Step 3. Apply glue to the surface of the pressed physical model and cast epoxy resin to obtain an experimental model; Step 4. Place the experimental model in a high-pressure container, and connect each gas collection interface to an external pressure gauge (5), a flow control valve (6), a flow meter, and an external gas source 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 the flow control valve (6), fill the gas, adjust the flow control valve (6) and the multi-layer combined production wellbore (4), and when the pressure of each pressure gauge (5) is 1.5-2.0 MPa lower than the surrounding pressure, close the flow control valve (6), remove the external gas source, and record the accumulated flow; Step 6. Open the flow control valve (6) and perform gas storage and production according to development needs; when the gas production flow rate is less than 10 mL / min, calculate the cumulative gas production and end the experiment.

8. The method for simulating multi-layer commingled production of gas reservoirs according to claim 7, characterized in that: In step 1, the experimental parameters include the number of simulated gas layers, the thickness and physical properties of each simulated gas layer, and the type and quality of artificial core base materials required for each simulated layer.

9. The method for simulating multi-layer commingled production of gas reservoirs according to claim 8, characterized in that: Specifically, the step 2 comprises: determining the type and quality of the artificial core base material required for each simulated gas layer according to the experimental parameters; weighing each base material, mixing the base materials of the same layer evenly and retaining them; placing the mixed base materials into the artificial core mold in sequence according to the actual order of each production layer of the gas reservoir; determining the type, height and diversion hole position of the multi-layer combined production wellbore (4); burying the multi-layer combined production wellbore (4) vertically in the center of the base material after being assembled, with the bottom in contact with the bottom of the mold; moving the mold into a pressurizing device, adding a cover plate with a hole in the middle, passing a circular hole through the upper end of the multi-layer combined production wellbore (4); pressurizing the cover plate to compact the artificial core base material; and taking it out from the mold after the pressing is completed and letting it stand until it is completely solidified to obtain a physical model; In step 4, the pressurization is specifically as follows: injecting a liquid with stable physical and chemical properties into the internal space of the high-pressure container through the external interface to apply confining pressure to the experimental model, and monitoring the confining pressure through the pressure gauge provided by the high-pressure container, and stopping the liquid injection when the confining pressure rises to the actual reservoir pressure.

10. The method for simulating multi-layer commingled production of gas reservoirs according to claim 9, characterized in that: In step 6, the gas storage exploitation according to development needs is specifically as follows: When the multi-layer commingled production wellbore (4) is a composite development wellbore, flow meters are connected behind each flow regulating valve (6), and the flow regulating valve (6) corresponding to the simulated gas layer to be developed is opened according to development requirements, and the multi-layer commingled production wellbore (4) and the flow regulating valve (6) are adjusted to perform gas storage and production; When the multi-layer combined production wellbore (4) is a rotary development wellbore, the multi-layer combined production wellbore (4) is rotated clockwise to a corresponding angle according to development requirements to carry out gas storage production.

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