Experimental device for measuring oil displacement recovery ratio of fault-karst reservoir well group

Abstract

The invention relates to the field of oilfield development, in particular to an experimental device for measuring the oil displacement recovery ratio of a fault-karst reservoir well group, which comprises a displacement system, a well group physical model system, a back pressure system and a metering system, the displacement system, the well group physical model system and the back pressure system are communicated in sequence, and the metering system is communicated with the back pressure system; the well group physical model system comprises an injection well physical model, a control valve and output well physical models, the injection well physical model is connected with the control valve in series, the number of the output well physical models is at least two, the output well physical models are connected with the control valve in parallel, and the multiple output well physical models correspond to the metering system. On the basis of the physical model device of each single well, in combination with the displacement device and the metering device, the device has the function of simulating multiple types of carbonate reservoirs, the accuracy and the working efficiency of an oil displacement recovery rate evaluation experiment are improved, and meanwhile, an experiment design reference basis is provided for a later adjustment scheme.

Description

Technical Field

[0001] This invention relates to the field of oilfield development, and in particular to an experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs. Background Technology

[0002] Fault-solved reservoirs are a relatively special type of reservoir, with their reservoir space mostly consisting of cavities formed by the fractured accumulation of carbonate rocks. In development practice, wells drilled in banded fault-solved reservoirs are mainly medium- to high-yield wells. Wells expanding outward along the main fault towards associated faults exhibit characteristics such as deteriorating formation fluid supply and reduced oil and gas charging. Oil-water flow is mainly characterized by pipe flow, with seepage features present in areas with wells developed by microfractures. After the initial flow period, water and gas injection are typically employed, but due to the strong heterogeneity of the reservoir space and the complexity of the oil-water relationship in fault-solved reservoirs, it is often difficult to achieve the desired results.

[0003] To determine the oil recovery rate in complex fractured-solution reservoirs, a single pressure vessel is typically filled with debris particles to simulate the reservoir. Displacement media are then introduced to measure the production of fluids and gas, from which the oil recovery rate is calculated. However, in actual production, multiple production wells are interconnected, and each well has different pressures, structural elevations, oil-water interfaces, and well spacing, making the simulation results from a single well unreliable. Summary of the Invention

[0004] To address the challenge of simulating complex conditions in well groups in the laboratory and determining the oil recovery rate of well groups in fractured-collapse reservoirs, this invention provides an experimental apparatus for determining the oil recovery rate of well groups in fractured-collapse reservoirs.

[0005] This invention provides an experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs, employing the following technical solution:

[0006] An experimental apparatus for determining the oil recovery rate of a well group in a fractured solution reservoir includes a displacement system, a well group physical model system, a back pressure system, and a metering system. The displacement system, the well group physical model system, and the back pressure system are connected in sequence, and the metering system is connected to the back pressure system.

[0007] The well group physical model system includes an injection well physical model, a control valve, and a production well physical model. The injection well physical model is connected in series with the control valve. There are at least two production well physical models and the production well physical models are connected in parallel with the control valve. The metering system has multiple corresponding to the production well physical models.

[0008] In one specific implementation, the displacement system includes a displacement pump, an intermediate container, and a connecting valve, wherein the intermediate container is connected to the outlet end of the displacement pump, and the connecting valve is connected between the intermediate container and the injection well physical model.

[0009] In one specific implementation, a one-way valve is connected between the intermediate container and the connecting valve, allowing flow from the intermediate container to the connecting valve.

[0010] In one specific implementation, there are two displacement pumps, two intermediate containers corresponding to the displacement pumps, and the connecting valve is a three-way valve.

[0011] In one specific implementation, the displacement pump is a constant-speed displacement pump.

[0012] In one specific implementation, the back pressure system includes a back pressure valve, a connecting valve, and a back pressure tracking pump. The connecting valve is connected to the outlet end of the back pressure tracking pump. Multiple back pressure valves are provided corresponding to the physical model of the production well, and all of the multiple back pressure valves are connected to the connecting valve.

[0013] In one specific implementation, the connecting valve and the back pressure tracking pump are configured as one, and the connecting valve controls the back pressure tracking pump to communicate with different back pressure valves.

[0014] In one specific implementation, the metering system includes a condenser, a collection bottle, and a flow meter. The collection bottle has a sealing cap on its opening. One end of the condenser is connected to the sealing cap, and the other end is connected to the back pressure system. The flow meter is connected to the sealing cap.

[0015] In one specific implementation, the flow meter is a wet flow meter, and the detection end of the flow meter is located inside the collection bottle.

[0016] In one specific implementation scheme, electric heating tapes are provided on the outer walls of the pipes in the displacement system, the well group physical model system, the back pressure system, and the metering system.

[0017] In summary, the present invention has at least one of the following beneficial technical effects:

[0018] 1. Multiple production well models are used to simulate multiple single wells, and then multiple production wells are connected to simulate the complex situation of well groups. Combined with displacement system, metering system and backpressure system, it is convenient to calculate the oil recovery rate of well groups under complex conditions and improve the accuracy of oil recovery rate.

[0019] 2. Two displacement pumps are used, one to deliver the displacement liquid and the other to deliver the displacement gas. The displacement liquid and the displacement gas are delivered separately through a connecting valve, which reduces the loss of displacement gas due to dissolution in the displacement liquid during transportation and improves the accuracy of the experiment.

[0020] 3. The electric heating belt is used to insulate the pipeline, reduce temperature loss during the experiment, make the experimental environment closer to the actual environment, and further improve the accuracy of the oil recovery rate obtained from the experiment.

[0021] 4. The one-way valve design ensures that the displacement medium can only be delivered from the intermediate container to the injection well physical model, which helps to guarantee the one-way delivery of the displacement medium and maintain pressure stability within the injection well physical model. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the experimental apparatus used to determine the oil recovery rate of well groups in fractured solution reservoirs.

[0023] Explanation of reference numerals in the attached diagrams: 110, Displacement system; 120, Well group physical model system; 130, Back pressure system; 140, Metering system; 1, Displacement pump; 2, Intermediate container; 3, Check valve; 4, Connecting valve; 5, Injection well physical model; 6, Control valve; 7, First production well physical model; 8, Second production well physical model; 9, Third production well physical model; 10, Back pressure valve; 11, Condenser; 12, Collection bottle; 13, Flow meter; 14, Connecting valve; 15, Back pressure tracking pump. Detailed Implementation

[0024] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below. Numerous specific details are set forth in the following description to provide a thorough understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and similar modifications can be made by those skilled in the art without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] In the description of this invention, it should be understood that if terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact, or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0029] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. Where applicable, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this invention are for illustrative purposes only and do not represent the only possible implementation.

[0030] Reference Figure 1 The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs includes a displacement system 110, a well group physical model system 120, a back pressure system 130, and a metering system 140. The well group physical model system 120 includes an injection well physical model 5, a control valve 6, and multiple production well physical models. The injection well physical model 5 is connected in series with the control valve 6, and the multiple production well physical models are connected in parallel with the control valve 6.

[0031] In this embodiment, three physical models of the producing wells are specifically set up. For ease of description, they are distinguished as the first producing well physical model 7, the second producing well physical model 8, and the third producing well physical model 9. The producing well physical models are used to simulate producing wells with different reservoir characteristics. For example, the first producing well physical model 7 simulates the reservoir characteristics of a porous carbonate reservoir by filling a container with carbonate rock cuttings; the second producing well physical model 8 simulates the reservoir characteristics of a high-angle fractured reservoir by vertically placing flaky carbonate rock blocks in a container; and the third producing well physical model 9 simulates the reservoir characteristics of a fractured-porosity reservoir by filling the bottom of the container with carbonate rock cuttings, vertically placing flaky carbonate rock blocks in the middle, and filling the top with carbonate rock cuttings, using a composite filling method. The physical models of injection well 5, first production well 7, second production well 8, and third production well 9 all have heating functions, which can simulate the formation temperature of actual production wells, making the physical models of injection well 5, first production well 7, second production well 8, and third production well 9 closer to reality, improving experimental accuracy and the representativeness of experimental results.

[0032] By setting different reservoir characteristics using the first producing well physical model 7, the second producing well physical model 8, and the third producing well physical model 9, the complex situation of the well group is simulated. The metering system 140 is used to obtain the metering of produced oil and gas, making the calculated oil recovery rate more representative.

[0033] Reference Figure 1 The control valve 6 is specifically a four-way valve. The injection well physical model 5 is connected to one of the first production well physical models 7, the second production well physical model 8, and the third production well physical model 9 through the four-way valve each time. This allows for the displacement of the first production well physical model 7, the second production well physical model 8, and the third production well physical model 9, realizing the displacement of the well group under complex conditions. This makes the experiment closer to the actual situation and improves the accuracy of the experimental results.

[0034] Reference Figure 1The backpressure system 130 includes backpressure valves 10, connecting valves 14, and backpressure tracking pumps 15. Three backpressure valves 10 are provided, each connected to a first production well physical model 7, a second production well physical model 8, and a third production well physical model 9, respectively. One connecting valve 14 and one backpressure tracking pump 15 are each provided. The connecting valves 14 are specifically four-way valves, connected to both the three backpressure valves 10 and the backpressure tracking pump 15. Through the control of the connecting valves 14, the backpressure tracking pump 15 connects to one backpressure valve 10 at a time, thereby regulating the pressure of one of the first, second, or third production well physical models 7, 8, or 9. Since the backpressure tracking pump 15 needs to maintain stable pressure within the production well physical model, typically, one backpressure tracking pump 15 is required for each production well physical model. By using the connecting valve 14, once one of the first production well physical models 7, 8, and 9 has completed pressure adjustment and stabilized, the connecting valve 14 controls the backpressure tracking pump 15 to connect with the other production well physical model to adjust and maintain pressure stability. For example, initially, the backpressure tracking pump 15 is connected to the first production well physical model 7. After the backpressure tracking pump 15 completes the pressure adjustment within the first production well physical model 7 and the pressure within the first production well physical model 7 remains stable, the connecting valve 14 controls the backpressure tracking pump 15 to connect with the second production well physical model 8 or the third production well physical model 9 to adjust pressure. This process continues until all three production well physical models—7, 8, and 9—have completed pressure adjustment and maintained stable pressure.

[0035] Reference Figure 1 The displacement system 110 includes two displacement pumps 1, two intermediate containers 2, and a connecting valve 4. The connecting valve 4 is specifically a three-way valve, which connects the two intermediate containers 2 to the injection well physical model 5, controlling that the injection well physical model 5 is connected to only one intermediate container 2 at any given time. The two displacement pumps 1 are connected to the two intermediate containers 2 respectively, providing pressure to each container. The displacement pumps 1 are constant-speed displacement pumps, providing a more stable flow rate, significantly reducing the impact of flow rate fluctuations on experimental results, and improving the accuracy of the results. One displacement pump 1 delivers the displacement liquid from the intermediate container 2, while the other displacement pump 1 delivers the displacement gas from the intermediate container 2. This allows for the displacement of crude oil first, followed by the displacement of gas, reducing the loss of displacement gas dissolved in the displacement liquid when it is delivered to the production well physical model, further improving experimental accuracy.

[0036] Reference Figure 1A one-way valve 3 connects the intermediate container 2 and the connecting valve 4. The one-way valve 3 ensures that the displacement medium in the intermediate container 2 can only flow along the intermediate container 2 towards the connecting valve 4, thus avoiding the influence of pressure changes during the operation of the connecting valve 4 on the displacement medium and the pressure in the injection well physical model 5.

[0037] Reference Figure 1 The metering system 140 corresponds to three physical models of the production wells, with each model corresponding to one of the three production well physical models: the first (7), the second (8), and the third (9). The metering system 140 includes a condenser 11, a collection bottle 12, and a flow meter 13. The flow meter 13 is a wet flow meter, capable of containing gas while measuring its volume. The collection bottle 12 is a conical flask with a sealing cap. One end of the condenser 11 is connected to the back pressure valve 10, and the other end passes through the sealing cap and connects to the collection bottle 12. The flow meter 13 is fixed to the sealing cap, and its detection end is inside the collection bottle 12.

[0038] In the physical models 7 (first producing well), 8 (second producing well), and 9 (third producing well), the crude oil discharged due to displacement is condensed by the condenser 11 and collected in the collection bottle 12. The gas discharged due to displacement is also collected in the collection bottle 12 by the flow meter 13, and its volume is measured. The oil recovery rate of the producing well can be calculated by using the mass of crude oil in the collection bottle 12 and the volume of gas measured by the flow meter 13.

[0039] Because the bottom layer temperature of actual injection and production wells differs from the room temperature in the laboratory, this temperature difference can cause errors in experimental results. To reduce temperature loss during the experiment and further improve the accuracy of the results, electric heating tape is wrapped around the outer walls of all pipes in the experimental apparatus used to determine the oil recovery rate of well groups in broken-solution reservoirs.

[0040] The implementation principle of this invention is as follows: The complex situation of a well group is simulated using injection well physical model 5, first production well physical model 7, second production well physical model 8, and third production well physical model 9. The pressure of the first production well physical model 7, second production well physical model 8, and third production well physical model 9 is adjusted by backpressure tracking pump 15 to ensure that the pressure within these models is the same as and stable as the pressure of the actual production well. Displacement pump 1 delivers displacement liquid and displacement gas to injection well physical model 5, thereby achieving displacement of the first production well physical model 7, second production well physical model 8, and third production well physical model 9. Collection bottle 12 collects the crude oil discharged from the first production well physical model 7, second production well physical model 8, and third production well physical model 9, and flow meter 13 collects the gas discharged from the first production well physical model 7, second production well physical model 8, and third production well physical model 9, measures the gas volume, and then calculates the oil recovery rate.

[0041] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs, characterized in that: It includes a displacement system (110), a well group physical model system (120), a back pressure system (130), and a metering system (140), wherein the displacement system (110), the well group physical model system (120), and the back pressure system (130) are connected in sequence, and the metering system (140) is connected to the back pressure system (130); The well group physical model system (120) includes an injection well physical model (5), a control valve (6), and a production well physical model. The injection well physical model (5) is connected in series with the control valve (6). There are at least two production well physical models. The production well physical models are connected in parallel with the control valve (6). The metering system (140) has multiple corresponding to the production well physical models.

2. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 1, characterized in that: The displacement system (110) includes a displacement pump (1), an intermediate container (2) and a connecting valve (4). The intermediate container (2) is connected to the outlet end of the displacement pump (1), and the connecting valve (4) is connected between the intermediate container (2) and the injection well physical model (5).

3. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 2, characterized in that: A one-way valve (3) is connected between the intermediate container (2) and the connecting valve (4), allowing the flow from the intermediate container (2) to the connecting valve (4).

4. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 2, characterized in that: Two displacement pumps (1) are provided, two intermediate containers (2) are provided corresponding to the displacement pumps (1), and the connecting valve (4) is a three-way valve.

5. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 2, characterized in that: The displacement pump (1) is a constant speed displacement pump.

6. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 1, characterized in that: The back pressure system (130) includes a back pressure valve (10), a connecting valve (14), and a back pressure tracking pump (15). The connecting valve (14) is connected to the outlet end of the back pressure tracking pump (15). Multiple back pressure valves (10) are provided corresponding to the physical model of the production well, and multiple back pressure valves (10) are connected to the connecting valve (14).

7. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 6, characterized in that: The connecting valve (14) and the back pressure tracking pump (15) are configured as one, and the connecting valve (14) controls the back pressure tracking pump (15) to connect with different back pressure valves (10).

8. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 1, characterized in that: The metering system (140) includes a condenser (11), a collection bottle (12) and a flow meter (13). The opening of the collection bottle (12) is provided with a sealing cap. One end of the condenser (11) is connected to the sealing cap, and the other end is connected to the back pressure system (130). The flow meter (13) is connected to the sealing cap.

9. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 8, characterized in that: The flow meter (13) is a wet flow meter, and the detection end of the flow meter (13) is located inside the collection bottle (12).

10. The experimental apparatus for determining the oil recovery rate of well groups in fractured solution reservoirs according to claim 1, characterized in that: Electric heating tapes are provided on the outer walls of the pipes in the displacement system (110), the well group physical model system (120), the back pressure system (130), and the metering system (140).

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