Experimental evaluation device and method for plugging efficiency of temporary plugging agent in natural crack

Abstract

The invention provides an experimental evaluation device and method for the plugging efficiency of a temporary plugging agent in a natural fissure.The experimental evaluation device comprises a first fissure plate used for simulating a main fissure, and the first fissure plate is communicated with a plurality of second fissure plates used for simulating branch fissures; a natural crack outlet end flow meter is arranged at a branch crack outlet in the second crack plate and is used for detecting the flow at the branch crack outlet; the device provided by the invention solves the problem that the existing evaluation of the temporary plugging agent in the natural fracture cannot really simulate the formation condition, and reduces the difference that the experimental evaluation result is inconsistent with the field application.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development and oil and gas production enhancement and transformation, and in particular belongs to a device and method for experimentally evaluating the plugging efficiency of a temporary plugging agent in a natural fracture. Background Art

[0002] In the process of unconventional oil and gas development, reservoir transformation measures are needed to establish industrial oil and gas production capacity. Reservoir transformation of oil and gas reservoirs is to pump high-pressure fluid into the reservoir to create cracks in the formation and increase the reservoir permeability. At present, scholars believe that the volume of reservoir transformation is positively correlated with the production capacity after transformation. The larger the transformation volume, the better the reservoir transformation effect. Temporary plugging and fracturing construction is a reservoir transformation technology that increases the transformation volume. Its purpose is to pump temporary plugging agents into artificial fractures to plug the micro-cracks that have already occurred in the formation, forcing the pressure in the artificial fractures to rise, so as to achieve the purpose of opening more fractures. Therefore, it is necessary to evaluate the plugging efficiency of temporary plugging agents for different natural fractures. The evaluation results help to optimize the type and combination of temporary plugging agents and other parameters to achieve the purpose of improving the reservoir transformation effect.

[0003] At present, domestic and foreign scholars often use experimental methods to evaluate the plugging efficiency of temporary plugging agents. For example: CN201710443854.0 "An experimental device for evaluating the temporary plugging performance of temporary plugging agents and its working method and application"; CN201720684446.X "An experimental device for evaluating the temporary plugging performance of temporary plugging agents"; CN202010161837.X "Dynamic experimental evaluation method for the temporary plugging effect of temporary plugging agents in cracks"; CN202011129962.9 "An evaluation device and evaluation method for the temporary plugging strength of temporary plugging agents", etc. In the above experimental devices and methods, the actual working conditions of temporary plugging agents in cracks are often simplified, and only the plugging characteristics of temporary plugging agents in single cracks or regular cracks are considered, which is quite different from the actual situation.

[0004] like Figure 1 As shown in the figure, in actual working conditions, the temporary plugging agent is carried by the fracturing fluid through the wellbore into the main crack of the artificial fracture, and moves with the fluid to the depth of the fracture. When it moves to the opened microcracks, due to the change in the width of the cracks, part of the temporary plugging agent accumulates in the microcracks, thereby reducing the fluid flow of the opened microcracks. At the same time, as the microcracks are gradually blocked by the temporary plugging agent, the pressure in the main crack rises, and more microcracks will be opened, achieving the effect of expanding the transformation volume.

[0005] Evaluating the migration and accumulation process of temporary plugging agents from main fractures to natural fractures is the key to evaluating the plugging efficiency of temporary plugging agents in natural fractures. However, the current evaluation devices and methods only consider the performance of temporary plugging agents in a single natural fracture and do not fully simulate the real conditions, which may cause the evaluation results to be inconsistent with the actual application effects. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a device and method for experimental evaluation of the plugging efficiency of temporary plugging agents in natural fractures, which solves the problem that the current evaluation of temporary plugging agents in natural fractures cannot truly simulate the formation conditions and reduces the difference between experimental evaluation results and field applications.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for experimental evaluation of the plugging efficiency of a temporary plugging agent in a natural fracture, comprising a first slit plate for simulating a main fracture, a plurality of second slit plates for simulating branch fractures connected to the first slit plate, a natural fracture outlet flow meter is arranged at the branch fracture outlet of the second slit plate for detecting the flow at the branch fracture outlet; the main fracture inlet on the first slit plate is connected to the outlet of a fluid temporary plugging agent pumping device.

[0008] Furthermore, the first seam plate is obtained by setting a seam width strip simulating a main crack between two transparent plates, and the second seam plate is obtained by setting a seam width strip simulating a natural branch crack between two transparent plates, wherein the width of the seam width strip in the second seam plate is smaller than the width of the seam width strip in the first seam plate, and the seam width strip in the second seam plate is processed by a carving method to have a curved surface consistent with a real natural crack.

[0009] Furthermore, the first slot plate is connected to the plurality of second slot plates via a valve.

[0010] Furthermore, an inlet total flow meter is provided between the outlet of the fluid temporary plugging agent pumping device and the main crack outlet of the first seam plate, for detecting the flow of the temporary plugging agent entering the main crack in the first seam plate.

[0011] Furthermore, a pressure sensor is provided between the inlet total flow meter and the main crack inlet of the first seam plate to detect the pressure change process in the main crack.

[0012] Furthermore, the main crack outlet of the first slot plate is connected to the main crack outlet manifold, and a main crack outlet flowmeter is provided between the main crack outlet of the first slot plate and the inlet of the main crack outlet manifold for detecting the flow of the fluid after passing through the first slot plate connected to multiple second slot plates.

[0013] Furthermore, the branch fracture outlets of the plurality of second fracture plates are respectively connected to the natural fracture outlet manifolds for collecting the fluids flowing out of the natural fractures.

[0014] Furthermore, the fluid temporary plugging agent pumping device includes a horizontal flow pump, a temporary plugging agent adding regulating valve, and a temporary plugging agent adding tank, wherein the first outlet of the horizontal flow pump and the outlet of the temporary plugging agent adding tank are connected to the main crack inlet of the first seam plate, and the second outlet of the horizontal flow pump is connected to the inlet of the temporary plugging agent adding tank through the temporary plugging agent adding regulating valve.

[0015] Furthermore, the displacement of the horizontal flow pump is determined by the number of the second slot plates.

[0016] The present invention also provides a method for using a device for experimentally evaluating the plugging efficiency of a temporary plugging agent in a natural fracture, and the specific steps are as follows:

[0017] S1 According to the actual natural fracture situation, the first seam plate and the second seam plate are selected, and the fluid temporary plugging agent pumping device, the first seam plate, the second seam plate and the flow meter at the outlet of the natural fracture are connected and assembled to obtain a temporary plugging agent plugging efficiency experimental evaluation device in the natural fracture;

[0018] S2 starts the fluid temporary plugging agent pumping device to pump the fluid into the main crack of the first seam plate. The flow meter at the outlet of the natural crack detects the fluid flow Q at the outlet of the branch crack of the second seam plate. 分前 ;

[0019] The S3 fluid temporary plugging agent pumping device continuously pumps the fluid into the main crack of the first seam plate, and at the same time pumps the temporary plugging agent into the main crack of the first seam plate. The flow meter at the outlet of the natural crack detects the fluid flow Q at the outlet of the branch crack of the second seam plate. 分后 ;

[0020] S4 calculates the temporary plugging agent plugging efficiency η of each branch crack in the second seam plate, and the formula is:

[0021] Temporary plugging agent plugging efficiency η=Q 分后 / Q 分前 .

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] The present invention provides a device for experimentally evaluating the plugging efficiency of a temporary plugging agent in a natural fracture. The device simulates the actual situation of a formation by connecting a plurality of second slit plates for simulating branch fractures on a first slit plate for simulating a main fracture, and arranges a natural fracture outlet flow meter at the main fracture entrance of the first slit plate and the branch fracture exit of the second slit plate to detect the flow change of the branch fracture on the second slit plate before and after the branch fracture is plugged by the temporary plugging agent. The complete process of the temporary plugging agent flowing in the main fracture on the first slit plate, migrating to the branch fractures on the plurality of second slit plates through the main fracture on the first slit plate, and flowing in the branch fracture on the second slit plate is simultaneously evaluated, the plugging characteristics of the temporary plugging agent in the natural fracture are truly restored, the plugging efficiency of the temporary plugging agent in the natural fracture is evaluated, and the plugging efficiency is used as a quantitative characterization means for the plugging situation of the natural fracture.

[0024] The number of the second seam plates of the present invention, and the shape and size of the branch cracks formed in the second seam plates can be adjusted according to the actual simulated conditions. The use of the device of the present invention can effectively solve the problem of simulating the plugging process of the temporary plugging agent on the natural cracks under real working conditions, and can simulate the evaluation of the plugging efficiency of the temporary plugging agent on different natural cracks when multiple branch cracks exist at the same time. The plugging efficiency can provide a theoretical basis for various process parameters such as the type, variety, ratio, and addition method of the temporary plugging agent in the natural cracks, and provide guidance for the optimization of engineering parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of temporary plugging fracturing principle. The white particles in the seam are temporary plugging agents.

[0026] Figure 2 Flow chart of the experimental evaluation device for the plugging efficiency of temporary plugging agents in natural fractures;

[0027] In the attached drawing: 1 horizontal flow pump, 2 temporary plugging agent adding regulating valve, 3 temporary plugging agent adding tank, 4 inlet total flow meter, 5 pressure sensor, 6 first seam plate, 7 second seam plate, 8 natural fracture outlet flow meter, 9 natural fracture outlet manifold, 10 main fracture outlet flow meter, 11 main fracture outlet manifold. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0029] The present invention provides a temporary plugging agent plugging efficiency experimental evaluation device for natural fractures, comprising a fluid temporary plugging agent pumping device, a first slit plate 6 for simulating a main fracture, a second slit plate 7 for simulating a branch fracture, a natural fracture outlet manifold 9 and a main fracture outlet manifold 11, wherein the outlet of the fluid temporary plugging agent pumping device is connected to the main fracture inlet on the first slit plate 6, a plurality of outlets are provided on the main fracture on the first slit plate 6, and the plurality of outlets are connected to the branch fracture inlet on the second slit plate 7 for simulating the actual formation situation, the branch fracture outlets on the plurality of second slit plates 7 are respectively connected to the natural fracture outlet manifold 9 for collecting the fluid flowing out of the natural fracture, the main fracture outlet on the first slit plate 6 is connected to the main fracture outlet manifold 11, the first slit plate 6 is connected to the plurality of second slit plates 7 via a valve, wherein the angle between the second slit plate 7 and the first slit plate 6 is adjustable;

[0030] An inlet total flow meter 4 and a pressure sensor 5 are arranged between the outlet of the fluid temporary plugging agent pumping device and the main crack inlet on the first seam plate 6. The inlet total flow meter 4 is used to detect the flow of the temporary plugging agent entering the main crack on the first seam plate 6; the pressure sensor 5 is arranged between the inlet total flow meter 4 and the main crack inlet on the first seam plate 6, and is used to detect the pressure change process in the main crack.

[0031] A natural fracture outlet flowmeter 8 is arranged between the branch fracture outlet on the second fracture plate 7 and the inlet of the natural fracture outlet manifold 9, for detecting the flow change of the branch fracture after being plugged by the temporary plugging agent, monitoring the plugging efficiency of each natural fracture in real time, and realizing a true simulation of the plugging process of the temporary plugging agent in the natural fracture.

[0032] A main crack outlet flowmeter 10 is provided between the main crack outlet on the first crack plate 6 and the inlet of the main crack outlet manifold 11, for detecting the flow rate of the fluid after passing through the main crack with multiple branch cracks;

[0033] Preferably, the first seam plate 6 can be obtained by arranging a seam width strip simulating the main crack between two transparent plates, and the material of the transparent plates is preferably transparent polycarbonate.

[0034] Preferably, a seam width strip simulating a natural branch crack is provided between two transparent plates, and the seam width strip is processed by engraving so that the curved surface is consistent with the real natural crack, thereby obtaining the second seam plate 7.

[0035] Preferably, the width of the seam width strip in the second seam plate 7 is smaller than the width of the seam width strip in the first seam plate 6, and the crack angle, crack width and crack length of the second seam plate 7 can be adjusted according to actual conditions.

[0036] Preferably, the fluid temporary plugging agent pumping device includes a horizontal flow pump 1, a temporary plugging agent adding regulating valve 2, and a temporary plugging agent adding tank 3, wherein the first outlet of the horizontal flow pump 1 is connected to the main crack inlet on the first seam plate 6 through the inlet total flow meter 4 and the pressure sensor 5; the second outlet of the horizontal flow pump 1 is connected to the inlet of the temporary plugging agent adding tank 3 through the temporary plugging agent adding regulating valve 2, and the outlet of the temporary plugging agent adding tank 3 is connected to the main crack inlet on the first seam plate 6 through the inlet total flow meter 4 and the pressure sensor 5; the inlet of the temporary plugging agent adding tank 3 is arranged at the top, and the outlet is arranged at the bottom.

[0037] The displacement of the advection pump 1 is determined by the number of the second slot plates 7 . One second slot plate 7 requires the displacement of the advection pump 1 to be 20 L / min. The displacements of multiple second slot plates 7 can be added together.

[0038] After the experiment starts, by adjusting the temporary plugging agent adding regulating valve 2, part of the fluid discharged from the horizontal flow pump 1 enters the top of the temporary plugging agent adding tank 3, pushing the temporary plugging agent in the temporary plugging agent adding tank 3 into the main crack of the first seam plate 6; the opening of the temporary plugging agent adding regulating valve 2 can control the temporary plugging agent adding speed.

[0039] The calculation method is:

[0040] 1. Set the advection pump 1 to the specified flow rate Q 总 ;

[0041] 2. Set different widths W of the branch cracks in the second seam plate 7n ;

[0042] 3. The horizontal flow pump 1 pumps the fluid into the main crack of the first seam plate 6. When the flow data is stable, the outlet flow Q of each branch crack in the second seam plate 7 is recorded. 分前1 , Q 分前2 , Q 分前3 , Q 分前4 …

[0043] 4. Adjust the temporary plugging agent to add the regulating valve 2 to the specified valve position, and the horizontal flow pump 1 pumps the temporary plugging agent and the fluid into the main crack of the first seam plate 6;

[0044] 5. When the outlet flow rate is stable, record the outlet flow rate Q of each branch crack in the second seam plate 7. 分后1 , Q 分后2 , Q 分后3 , Q 分后4 …

[0045] 6. Calculate the temporary plugging agent plugging efficiency η of each branch crack in the second seam plate 7;

[0046] Temporary plugging agent plugging efficiency η=Q 分后 / Q 分前

[0047] Example 1

[0048] like Figure 2 As shown, the second slit plates 7 are provided in 5 numbers, 3 of which are distributed on the upper part of the first slit plate 6, and 2 of which are distributed on the lower part of the first slit plate 6. The angles between the second slit plates 7 and the first slit plates 6 are respectively 30° (slit width 2mm), 60° (slit width 3mm), 90° (slit width 5mm) on the upper part of the first slit plate 6, and 30° (slit width 2mm), 60° (slit width 3mm) on the lower part of the first slit plate 6.

[0049] The specific steps are as follows:

[0050] 1. The curvature of the branch crack in the second seam plate 7 of the experimental equipment is set in the form of a real natural crack;

[0051] 2. Put 2mm temporary plugging agent particles into temporary plugging agent adding tank 3.

[0052] 3. Turn on the large displacement horizontal flow pump and set the flow rate to 12L / min. When the flow rate of the inlet flow meter stabilizes at 12L / min, record the value P of the pressure sensor 5 and the outlet flow rate Q of the branch crack in the second seam plate 7. 分前1 , Q 分前2 , Q 分前3 , Q 分前4 , Q 分前 5.

[0053] 4. Control the temporary plugging agent to be added into the regulating valve 2 to a valve position of 50%, and the temporary plugging agent enters the main crack of the first seam plate 6;

[0054] 5. Real-time monitoring of the outlet flow of the branch crack in the second seam plate 7, and record Q after the outlet flow stabilizes. 分后1 , Q 分后2 , Q 分后3 , Q 分后4 , Q 分后5 .

[0055] 6. Calculate the temporary plugging efficiency η of each branch crack 分1 , η 分2 , η 分3 , η 分4 , η 分5 .

[0056] 7. Cleaning process.

Claims

1. An experimental evaluation device for the plugging efficiency of temporary plugging agents in natural fractures, characterized in that: The invention comprises a first slit plate (6) for simulating a main crack, the first slit plate (6) is connected to a plurality of second slit plates (7) for simulating branch cracks, a natural crack outlet flow meter (8) is arranged at the outlet of the branch cracks on the second slit plate (7) for detecting the flow at the outlet of the branch cracks; the main crack inlet on the first slit plate (6) is connected to the outlet of a fluid temporary plugging agent pumping device.

2. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: The first seam plate (6) is obtained by setting a seam width strip simulating a main crack between two transparent plates, and the second seam plate (7) is obtained by setting a seam width strip simulating a natural branch crack between two transparent plates, wherein the width of the seam width strip in the second seam plate (7) is smaller than the width of the seam width strip in the first seam plate (6), and the seam width strip in the second seam plate (7) is processed by a carving method to have a curved surface consistent with a real natural crack.

3. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: The first slot plate (6) is connected to a plurality of second slot plates (7) via valves.

4. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: An inlet total flow meter (4) is provided between the outlet of the fluid temporary plugging agent pumping device and the main crack outlet of the first seam plate (6) for detecting the flow of the temporary plugging agent entering the main crack in the first seam plate (6).

5. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 4, characterized in that: A pressure sensor (5) is provided between the inlet total flow meter (4) and the main crack inlet of the first crack plate (6) for detecting the pressure change process in the main crack.

6. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: The main crack outlet of the first slit plate (6) is connected to the main crack outlet manifold (11), and a main crack outlet flowmeter (10) is provided between the main crack outlet of the first slit plate (6) and the inlet of the main crack outlet manifold (11) for detecting the flow of the fluid after passing through the first slit plate (6) connected to a plurality of second slit plates (7).

7. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: The branch fracture outlets of the plurality of second fracture plates (7) are respectively connected to the natural fracture outlet manifold (9) for collecting the fluid flowing out of the natural fractures.

8. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 1, characterized in that: The fluid temporary plugging agent pumping device comprises a horizontal flow pump (1), a temporary plugging agent adding regulating valve (2), and a temporary plugging agent adding tank (3), wherein the first outlet of the horizontal flow pump (1) and the outlet of the temporary plugging agent adding tank (3) are connected to the main crack inlet of the first seam plate (6), and the second outlet of the horizontal flow pump (1) is connected to the inlet of the temporary plugging agent adding tank (3) through the temporary plugging agent adding regulating valve (2).

9. The device for evaluating the plugging efficiency of a temporary plugging agent in a natural fracture according to claim 8, characterized in that: The displacement of the horizontal flow pump (1) is determined by the number of the second slot plates (7).

10. A method for using a temporary plugging agent plugging efficiency experimental evaluation device for natural fractures according to any one of claims 1 to 9, characterized in that: The specific steps are as follows: S1, according to the actual natural fracture situation, the first seam plate (6) and the second seam plate (7) are selected, and the fluid temporary plugging agent pumping device, the first seam plate (6), the second seam plate (7) and the natural fracture outlet flow meter (8) are connected and assembled to obtain a temporary plugging agent plugging efficiency experimental evaluation device in natural fractures; S2 starts the fluid temporary plugging agent pumping device to pump the fluid into the main crack of the first seam plate (6), and the flow meter (8) at the outlet of the natural crack detects the fluid flow Q at the outlet of the branch crack of the second seam plate (7) 分前 ; The fluid temporary plugging agent pumping device S3 continuously pumps the fluid into the main crack of the first seam plate (6), and at the same time pumps the temporary plugging agent into the main crack of the first seam plate (6). The flow meter (8) at the outlet of the natural crack detects the fluid flow Q at the outlet of the branch crack of the second seam plate (7). 分后 ; S4 calculates the temporary plugging agent plugging efficiency η of the branch cracks in each second seam plate (7), and the formula is: Temporary plugging agent plugging efficiency η=Q 分后 / Q 分前 .

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