Device and method for evaluating plugging strength of plugging agent in pore throat

Abstract

The invention belongs to the field of petroleum recovery, and discloses a device and method for evaluating the plugging strength of a plugging agent in a pore throat, the device comprises a displacement fluid input unit, a plugging agent input unit and a plugging strength detection unit, and an outlet of the displacement fluid input unit is connected with an inlet of the plugging strength detection unit; an outlet of the plugging agent input unit is connected with an inlet of the plugging strength detection unit. By designing the device for evaluating the plugging strength of the plugging agent in the pore throat, the plugging performance of the plugging agent in the pore throat can be simply and efficiently measured, meanwhile, a series of pipelines with different inner diameters are prefabricated according to the size, the length and the bending degree of the pore throat needing to be simulated, and a liquid storage tank, a high-pressure constant-flow pump and a feeding container are matched to simulate the plugging strength of the plugging agent in the pore throat. The one-way valve and the pressure sensor are used for evaluating the plugging performance of the plugging agent in pore throats with different diameters, different lengths and different bending degrees.

Description

Technical Field

[0001] The invention belongs to the field of oil recovery, and in particular relates to a device and a method for evaluating the plugging strength of a plugging agent in a pore throat. Background Art

[0002] The plugging strength is an important performance indicator in the field of oil recovery. In the field of oil recovery, the displacement technology is often used to improve the oil recovery rate, that is, using plugging agents to block some of the pores in the formation, so that the displacement fluid cannot pass through, forcing the fluid to turn to other pores and displace the oil in other pores. Whether the displacement material can block the pores and whether it will be washed away by the high-pressure fluid is one of the keys to the success of this technology.

[0003] There is no standard definition of plugging strength and no authoritative testing method. Currently, there are two methods for evaluating plugging strength:

[0004] One is to conduct a core flow experiment, that is, the displacement fluid flows through the core under high pressure, then the pores in the core are blocked with a plugging agent, and then the displacement fluid is used to displace the core, and the pressure difference before and after is measured, which is the plugging strength. The disadvantages of this method are: (1) the pore throat distribution of the rock sample is complex, and there are multiple criss-crossing throats in the rock, some of which are connected and some are not connected. It is difficult to examine the plugging characteristics of the plugging agent in a single throat. (2) The core samples vary greatly, making it difficult to conduct repeated experiments, and it is impossible to compare different plugging agents under the same standard.

[0005] The second method is to place the screen on a fixed base, place the plugging agent on a prefabricated screen (orifice plate) with holes of different diameters, pump fluid to squeeze the plugging agent, and measure the pressure when the plugging agent just passes through the screen, which is defined as the compressive strength. This is also the method used in the "Q / SY 17002-2016 Technical Specifications for Water-Absorbing Expandable Particles for Profile Control and Water Blockage". The advantage of this method is that it avoids the use of cores, has good repeatability, and can compare the performance of different plugging agents under the same standard. The disadvantage is that the screen cannot simulate the actual pore throat shape, and the measured compressive strength data used to characterize the performance of the plugging agent is very different from the actual use. Summary of the invention

[0006] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a device and method for evaluating the plugging strength of a plugging agent in a pore throat, which can simply and efficiently measure the plugging performance of the plugging agent in the pore throat. At the same time, a series of pipelines with different inner diameters are pre-fabricated according to the pore throat size, length and curvature to be simulated, and a liquid storage tank, a high-pressure constant flow pump, a feeding container, a one-way valve and a pressure sensor are used to evaluate the plugging performance of the plugging agent in pore throats with different diameters, lengths and curvatures.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A device for evaluating the plugging strength of a plugging agent in a pore throat, comprising: a displacement fluid input unit, a plugging agent input unit, and a plugging strength detection unit.

[0009] The outlet of the displacement fluid input unit is connected to the inlet of the plugging strength detection unit;

[0010] The outlet of the plugging agent input unit is connected to the inlet of the plugging strength detection unit;

[0011] The plugging strength detection unit is used to detect the plugging strength of the plugging agent under different pore throat sizes, lengths and curvatures.

[0012] Furthermore, the outlet and the inlet of the blocking strength detection unit are respectively provided with a first pressure sensor and a second pressure sensor, and the first pressure sensor and the second pressure sensor are detachably connected via a capillary tube.

[0013] Furthermore, the capillary tube includes a series of pipes with different inner diameters prefabricated according to pore throat size, length and tortuosity.

[0014] Furthermore, the displacement fluid input unit includes a first liquid storage tank and a high-pressure constant-flow pump connected by pipelines.

[0015] Furthermore, the plugging agent input unit includes a material storage container, a first one-way valve and a second one-way valve which are sequentially connected through a pipeline.

[0016] Furthermore, the outlet of the blocking strength detection unit is connected to the second liquid storage tank.

[0017] In another aspect, the present invention discloses a method for evaluating the plugging strength of a plugging agent in a pore throat, comprising the following steps:

[0018] The displacement fluid is pumped into the plugging strength detection unit by using the displacement fluid input unit to obtain the inlet pressure P1 and the outlet pressure P2 of the plugging strength detection unit;

[0019] The plugging agent is input into the plugging strength detection unit by using the plugging agent input unit, and the inlet pressure P1′ and the outlet pressure P2′ of the plugging strength detection unit are obtained;

[0020] The plugging strength M is calculated by P1, P1′, P2, and P2′. The calculation formula is as follows:

[0021]

[0022] Further, the displacement fluid is pumped into the plugging strength detection unit by using the displacement fluid input unit to obtain the inlet pressure P1 and the outlet pressure P2 of the plugging strength detection unit, including:

[0023] The second one-way valve is closed, and the displacement fluid is pumped into the capillary by a high-pressure constant-flow pump. After the displacement fluid flows stably, the first pressure sensor reading P1 and the second pressure sensor reading P2 are recorded.

[0024] Further, the plugging agent is input into the plugging strength detection unit by using the plugging agent input unit to obtain the inlet pressure P1′ and the outlet pressure P2′ of the plugging strength detection unit, including:

[0025] Open the first one-way valve to allow the plugging agent to enter the pipeline between the first one-way valve and the second one-way valve;

[0026] The first one-way valve is closed, and the second one-way valve is opened to allow the plugging agent to enter the capillary. After the fluid flow is stabilized, the first pressure sensor reading P1′ and the second pressure sensor reading P2′ are recorded.

[0027] Furthermore, the capillary is a series of detachable pipelines with different inner diameters that are prefabricated according to the pore throat size, length and tortuosity that need to be simulated.

[0028] Technical effects and advantages of the present invention:

[0029] 1. The present invention designs a plugging device with a capillary, wherein the capillary is a series of pipelines with different inner diameters prefabricated according to the size, length and curvature of the pore throat to be simulated, and can be disassembled, so as to facilitate the evaluation of the plugging strength of the plugging agent under high pressure for pore throats of different diameters, lengths and curvature shapes, and to examine the plugging characteristics of the plugging agent in a single throat. The measured compressive strength data for characterizing the performance of the plugging agent is consistent with the actual usage, and the simulation effect is good.

[0030] 2. The present invention defines a method for calculating the plugging strength, the calculation process is simple, and the plugging performance of the plugging agent under corresponding pore throat conditions can be simply and efficiently characterized.

[0031] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a device for evaluating the plugging strength of a plugging agent in a pore throat according to the present invention;

[0033] Figure 2 The present invention is a flow chart of a method for evaluating the plugging strength of a plugging agent in a pore throat. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present invention provides a device for evaluating the plugging strength of a plugging agent in a pore throat, comprising: a displacement fluid input unit, a plugging agent input unit, and a plugging strength detection unit.

[0036] The outlet of the displacement fluid input unit is connected to the inlet of the plugging strength detection unit;

[0037] The outlet of the plugging agent input unit is connected to the inlet of the plugging strength detection unit.

[0038] Figure 1 FIG. 1 is a schematic diagram of a device for evaluating the plugging strength of a plugging agent in a pore throat in some embodiments of the present invention. Figure 1 As shown, the outlet and the inlet of the blocking strength detection unit are respectively provided with a first pressure sensor and a second pressure sensor, and the first pressure sensor and the second pressure sensor are detachably connected via a capillary.

[0039] In some embodiments of the present invention, the capillary tube includes a series of prefabricated pipes with different inner diameters according to pore throat size, length and tortuosity.

[0040] In some embodiments of the present invention, the displacement fluid input unit includes a first liquid storage tank and a high-pressure constant-flow pump connected by a pipeline, and the high-pressure constant-flow pump is used to pump the displacement fluid in the first liquid storage tank into the plugging strength detection unit.

[0041] In some embodiments of the present invention, the plugging agent input unit includes a material storage container, a first one-way valve and a second one-way valve connected in sequence by a pipeline, wherein the material storage container is used to store the plugging agent, and the first one-way valve and the second one-way valve are located between the material storage container and the plugging strength detection unit.

[0042] In some embodiments of the present invention, the outlet of the plugging strength detection unit is connected to a second fluid storage tank for receiving the displacement fluid flowing out of the plugging strength detection unit.

[0043] On the other hand, Figure 2 As shown, the present invention also discloses a method for evaluating the plugging strength of a plugging agent in a pore throat, comprising the following steps:

[0044] The displacement fluid is pumped into the plugging strength detection unit by using the displacement fluid input unit to obtain the inlet pressure P1 and the outlet pressure P2 of the plugging strength detection unit;

[0045] Using a plugging agent input unit to input the plugging agent into the plugging strength detection unit, and obtaining an inlet pressure P1′ and an outlet pressure P2′ of the plugging strength detection unit;

[0046] The plugging strength M is calculated by P1, P1′, P2, and P2′. The calculation formula is as follows:

[0047]

[0048] The larger the M is, the better the plugging effect of the plugging agent is.

[0049] In some embodiments of the present invention, a displacement fluid input unit is used to pump a displacement fluid into a plugging strength detection unit, and an inlet pressure P1 and an outlet pressure P2 of the plugging strength detection unit are obtained, including:

[0050] The second one-way valve is closed, and the displacement fluid is pumped into the capillary by a high-pressure constant-flow pump. After the displacement fluid flows stably, the first pressure sensor reading P1 and the second pressure sensor reading P2 are recorded.

[0051] In some embodiments of the present invention, the plugging agent is input into the plugging strength detection unit by using the plugging agent input unit, and the inlet pressure P1′ and the outlet pressure P2′ of the plugging strength detection unit are obtained, including:

[0052] Open the first one-way valve to allow the plugging agent to enter the pipeline between the first one-way valve and the second one-way valve;

[0053] Close the first one-way valve and open the second one-way valve to allow the plugging agent to enter the capillary. After the fluid flow stabilizes, record the first pressure sensor reading P1′ and the second pressure sensor reading P2′.

[0054] In some embodiments of the present invention, the capillary is a series of detachable pipelines with different inner diameters that are prefabricated according to the size, length and tortuosity of the pore throat to be simulated.

[0055] In summary, the present invention discloses a device and method for evaluating the plugging strength of a plugging agent in a pore throat, which can simply and efficiently measure the plugging performance of the plugging agent in the pore throat. At the same time, a series of pipelines with different inner diameters can be pre-fabricated according to the pore throat size, length and curvature to be simulated, and a liquid storage tank, a high-pressure constant flow pump, a feeding container, a one-way valve and a pressure sensor can be used to evaluate the plugging performance of the plugging agent in pore throats with different diameters, lengths and curvatures. In combination with the corresponding plugging strength calculation method, the plugging performance of different plugging agents in different pore throats can be quickly and accurately characterized, which is of great significance for improving the performance of the plugging agent, optimizing the plugging process parameters, and selecting the plugging agent under the same mark, thereby improving the plugging effect and increasing the oil recovery rate.

[0056] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for evaluating the plugging strength of a plugging agent in a pore throat, characterized in that: include: Displacement fluid input unit, plugging agent input unit, plugging strength detection unit, The outlet of the displacement fluid input unit is connected to the inlet of the plugging strength detection unit; The outlet of the plugging agent input unit is connected to the inlet of the plugging strength detection unit; The plugging strength detection unit is used to detect the plugging strength of the plugging agent under different pore throat sizes, lengths, and curvatures.

2. A device for evaluating the plugging strength of a plugging agent in a pore throat according to claim 1, characterized in that: The outlet and the inlet of the blocking strength detection unit are respectively provided with a first pressure sensor and a second pressure sensor, and the first pressure sensor and the second pressure sensor are detachably connected via a capillary tube.

3. A device for evaluating the plugging strength of a plugging agent in a pore throat according to claim 2, characterized in that: The capillary tube includes a series of pipelines with different inner diameters prefabricated according to pore throat size, length and tortuosity.

4. The device for evaluating the plugging strength of a plugging agent in a pore throat according to claim 1, characterized in that: The displacement fluid input unit includes a first liquid storage tank and a high-pressure constant-flow pump connected by pipelines.

5. The device for evaluating the plugging strength of a plugging agent in a pore throat according to claim 1, characterized in that: The plugging agent input unit includes a material storage container, a first one-way valve and a second one-way valve which are sequentially connected through a pipeline.

6. A device for evaluating the plugging strength of a plugging agent in a pore throat according to any one of claims 1 to 5, characterized in that: The outlet of the blocking strength detection unit is connected to the second liquid storage tank.

7. A method for evaluating the plugging strength of a plugging agent in a pore throat, characterized in that: The method comprises the following steps: Using a displacement fluid input unit to pump a displacement fluid into a plugging strength detection unit, and obtaining an inlet pressure P1 and an outlet pressure P2 of the plugging strength detection unit; The plugging agent is input into the plugging strength detection unit by using the plugging agent input unit to obtain the inlet pressure P1 of the plugging strength detection unit. ′ and outlet pressure P2 ′ ; Through the P1, P1 ′ , P2, P2 ′ Calculate the plugging strength M, the calculation formula is as follows:

8. A method for evaluating the plugging strength of a plugging agent in a pore throat according to claim 7, characterized in that: The method of using the displacement fluid input unit to pump the displacement fluid into the plugging strength detection unit to obtain the inlet pressure P1 and the outlet pressure P2 of the plugging strength detection unit includes: Close the second one-way valve, pump the displacement fluid into the capillary by a high-pressure constant-flow pump, and after the displacement fluid flows steadily, record the first pressure sensor reading P1 and the second pressure sensor reading P2.

9. A method for evaluating the plugging strength of a plugging agent in a pore throat according to claim 7, characterized in that: The plugging agent input unit is used to input the plugging agent into the plugging strength detection unit to obtain the inlet pressure P1 of the plugging strength detection unit. ′ and outlet pressure P2 ′ ,include: Open the first one-way valve to allow the plugging agent to enter the pipeline between the first one-way valve and the second one-way valve; Close the first one-way valve and open the second one-way valve to allow the plugging agent to enter the capillary. After the fluid flow stabilizes, record the first pressure sensor reading P1. ′ and the second pressure sensor indicates P2 ′ .

10. A method for evaluating the plugging strength of a plugging agent in a pore throat according to any one of claims 8 to 9, characterized in that: The capillary is a series of detachable pipelines with different inner diameters that are prefabricated according to the pore throat size, length and bending degree that need to be simulated.

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