Indoor evaluation device and method for original leakage pressure and leakage pressure after plugging

Abstract

The application discloses a kind of original leakage pressure and leakage pressure after plugging indoor evaluation device and method, including pressure chamber component, confining pressure pipeline component, confining pressure inner container, simulation casing pipeline component, slit insert block and controller, the both ends of confining pressure pipeline component are connected hydraulic oil source and containing cavity respectively;Confining pressure inner container is set in the containing cavity of pressure chamber component and is used to be set on the outside of core sample, for applying confining pressure pressure to core sample by hydraulic oil;The both ends of simulation casing pipeline component are connected drilling fluid source and sample deep hole of core sample respectively, for transporting drilling fluid to sample deep hole;Slit insert block is used to be inserted in slit;Controller is connected with confining pressure pipeline component, simulation casing pipeline component communication and is used to determine the original leakage pressure and leakage pressure after plugging of core sample, with the advantages that it is easy and quick to operate, reduces the evaluation difficulty, is favorable for improving the simulation effect of drilling fluid leakage pressure measurement under different conditions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of lost circulation pressure measurement, and particularly relates to a device and method for laboratory evaluation of original lost circulation pressure and lost circulation pressure after plugging. BACKGROUND

[0002] With the rapid development of oil and gas exploration and development technology, drilling engineering has become an important link of oil and gas field development. At present, drilling fluid loss frequently occurs, which becomes a key factor restricting the safe and efficient drilling engineering. Drilling fluid loss refers to the phenomenon that drilling fluid flows into the formation when the drilling fluid pressure is greater than the formation pressure. The lost circulation pressure refers to the minimum pressure required for drilling fluid to enter the formation pores or fractures. In order to avoid the occurrence of drilling fluid loss, it is necessary to first determine the lost circulation pressure when well leakage occurs, and then control the drilling fluid pressure.

[0003] However, due to the complexity of formation parameters, the measurement of drilling fluid loss pressure under different conditions is difficult and the accuracy of the results is low. SUMMARY

[0004] The purpose of the present application is to provide a device for laboratory evaluation of original lost circulation pressure and lost circulation pressure after plugging, so as to improve the simulation effect of drilling fluid loss pressure measurement under different conditions.

[0005] To achieve the above purpose, the first aspect of the present application provides a device for laboratory evaluation of original lost circulation pressure and lost circulation pressure after plugging, which comprises:

[0006] A pressure chamber assembly, a containing cavity for containing a core sample is formed in the pressure chamber assembly;

[0007] A confining pressure pipeline assembly, two ends of the confining pressure pipeline assembly are respectively connected with a hydraulic oil source and the containing cavity, and the confining pressure pipeline assembly is used for conveying hydraulic oil to the containing cavity;

[0008] A confining pressure liner, which is arranged in the containing cavity and used for sleeving outside the core sample, is used for applying confining pressure to the core sample by hydraulic oil;

[0009] A simulated casing pipeline assembly, two ends of the simulated casing pipeline assembly are respectively connected with a drilling fluid source and a sample deep hole of the core sample, and the simulated casing pipeline assembly is used for conveying drilling fluid to the sample deep hole;

[0010] A slot insertion block, which is used for inserting into the slot;

[0011] A controller, which is in communication connection with the confining pressure pipeline assembly and the simulated casing pipeline assembly, and is used for determining a lost circulation pressure array of the core sample, the lost circulation pressure array comprising original lost circulation pressure and lost circulation pressure after plugging.

[0012] In the embodiments of the present application, the confining pressure pipeline assembly comprises:

[0013] The first pipeline is connected between the hydraulic oil source and the accommodating cavity.

[0014] The first adjusting member is arranged on the first pipeline and is used for adjusting the pressure of the hydraulic oil.

[0015] In the embodiment of the present application, the analog casing pipeline assembly comprises:

[0016] The second pipeline is connected between the drilling fluid source and the sample deep hole.

[0017] The second adjusting member is arranged on the second pipeline and is used for adjusting the pressure of the drilling fluid.

[0018] In the embodiment of the present application, the pressure chamber assembly comprises a top plate, a bottom plate, a shell, a first sealing rubber ring and a second sealing rubber ring, the top plate and the bottom plate are vertically spaced apart, the shell is arranged between the top plate and the bottom plate, and the two ends of the shell are detachably connected with the top plate and the bottom plate, the top plate, the bottom plate and the shell jointly enclose the accommodating cavity, the first sealing rubber ring is arranged between the top plate and the confining pressure liner and is used for sealing the gap between the top plate and the confining pressure liner, and the second sealing rubber ring is arranged between the bottom plate and the confining pressure liner and is used for sealing the gap between the bottom plate and the confining pressure liner.

[0019] In the embodiment of the present application, the horizontal section of the slotted insert block is wedge-shaped.

[0020] In the second aspect of the present application, a raw leakage pressure and post-plugging leakage pressure indoor evaluation method is provided, which is applicable to the raw leakage pressure and post-plugging leakage pressure indoor evaluation device described above and comprises:

[0021] The confining pressure pipeline assembly is controlled to deliver the hydraulic oil into the accommodating cavity to apply a first confining pressure to the core sample and make the slotted insert block in a first closed state;

[0022] The analog casing pipeline assembly is controlled to deliver the drilling fluid with gradually increasing pressure to the sample deep hole of the core sample;

[0023] It is determined that the drilling fluid flows out of the slotted insert block;

[0024] The first pressure of the drilling fluid is obtained;

[0025] The confining pressure pipeline assembly is controlled to stop delivering the hydraulic oil into the accommodating cavity, and the analog casing pipeline assembly is controlled to stop delivering the drilling fluid to the sample deep hole;

[0026] The slotted insert block is inserted into the slotted insert block;

[0027] controlling the confining pressure line assembly to deliver hydraulic oil into the containing cavity to apply a second confining pressure to the core sample and to place the slit in a second closed state;

[0028] controlling the analog casing line assembly to deliver drilling fluid again to the sample bore of the core sample;

[0029] determining that the drilling fluid flows out of the slit again;

[0030] obtaining a second pressure of the drilling fluid;

[0031] determining a leak-off pressure array according to the first pressure and the second pressure.

[0032] In the embodiments of the present application, the original leak-off pressure and the leak-off pressure after plugging indoor evaluation further comprises a first adjusting member and a second adjusting member, and the original leak-off pressure and the leak-off pressure after plugging indoor evaluation method further comprises:

[0033] controlling the first adjusting member to adjust the pressure of the hydraulic oil to a first confining pressure to place the slit in a first closed state after controlling the confining pressure line assembly to deliver hydraulic oil into the containing cavity; and

[0034] controlling the first adjusting member to adjust the pressure of the hydraulic oil to a second confining pressure to place the slit in a second closed state after controlling the confining pressure line assembly to deliver hydraulic oil into the containing cavity again.

[0035] In the embodiments of the present application, the first confining pressure is determined according to the following manner:

[0036]

[0037]

[0038] wherein, is a first preset borehole stress; is a second preset borehole stress; is a third preset borehole stress; is a preset borehole surface shear stress; is a preset borehole radius; is a preset borehole pressure; is an angle of the core sample in a cylindrical coordinate system; is a distance between the core sample and an origin in the cylindrical coordinate system; is the first confining pressure.

[0039] In the embodiments of the present application, determining that the drilling fluid flows out of the slit or determining that the drilling fluid flows out of the slit again comprises:

[0040] obtaining a flow value of the drilling fluid at an output end of the slit;

[0041] In a case where the flow value reaches a preset overflow flow value, it is determined that the drilling fluid flows out of the slit of the core sample.

[0042] In the embodiments of the present application, determining that the drilling fluid flows out of the slit or determining that the drilling fluid flows out of the slit again comprises:

[0043] An output end of the slit is obtained.

[0044] In a case where the pressure value reaches a preset overflow pressure value, it is determined that the drilling fluid flows out of the slit of the core sample.

[0045] According to the technical scheme, the original leakage pressure and post-plugging leakage pressure indoor evaluation device comprises a pressure chamber assembly, a confining pressure pipeline assembly, a confining pressure liner, a simulated casing pipeline assembly, a slit insertion block, and a controller. The pressure chamber assembly is formed with an accommodation cavity for accommodating a core sample. The confining pressure pipeline assembly is connected with a hydraulic oil source and the accommodation cavity at two ends, for conveying hydraulic oil to the accommodation cavity. The confining pressure liner is arranged in the accommodation cavity and is used for sleeving outside the core sample, for applying confining pressure to the core sample through the hydraulic oil. The simulated casing pipeline assembly is connected with a drilling fluid source and a sample deep hole of the core sample at two ends, for conveying drilling fluid to the sample deep hole. The slit insertion block is used for inserting into the slit. The controller is in communication connection with the confining pressure pipeline assembly and the simulated casing pipeline assembly, and is used for determining a leakage pressure array of the core sample, wherein the leakage pressure array comprises the original leakage pressure and the post-plugging leakage pressure. The original leakage pressure and post-plugging leakage pressure indoor evaluation device has the advantages of simple structure, accurate evaluation of the leakage pressure array, simple and fast operation, reduced evaluation difficulty of the leakage pressure array, and improved simulation effect of the drilling fluid leakage pressure measurement under different conditions.

[0046] Other features and advantages of the embodiments of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0047] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used to explain the embodiments of the present application together with the following specific embodiments, but do not constitute a limitation of the embodiments of the present application. For those skilled in the art, other drawings can be obtained from the structures shown in the drawings without creative labor. In the drawings:

[0048] Figure 1A structure schematic view of the original leakage pressure and the leakage pressure after plugging indoor evaluation device according to the specific embodiment of the present application;

[0049] Figure 2 A front view of the original leakage pressure and the leakage pressure after plugging indoor evaluation device in Figure 1

[0050] Figure 3 A top view of the original leakage pressure and the leakage pressure after plugging indoor evaluation device in Figure 1

[0051] Figure 4 A structure schematic view of the pressure container of the original leakage pressure and the leakage pressure after plugging indoor evaluation device in Figure 1

[0052] A front view of the pressure container in Figure 5 Figure 4 A sectional view of the pressure container in I-I direction in

[0053] Figure 6 Figure 5 A sectional view of the conventional core in A-A direction in

[0054] Figure 7 A top view of the interface core;

[0055] Figure 8 A sectional view of the interface core in B-B direction in Figure 7

[0056] A top view of the fracture-cave core; Figure 9

[0057] A sectional view of the fracture-cave core in C-C direction in Figure 10 Figure 7 A top view of the interbed core;

[0058] Figure 11 A sectional view of the interbed core in D-D direction in

[0059] Figure 12 Figure 7 A structure schematic view of the slit-inserted block in

[0060] Figure 13 A structure schematic view of the slit-inserted block in

[0061] Figure 14 A structure schematic view of the slit-inserted block in Figure 7

[0062] Figure 15 Figure 1 A structure schematic view of the slit-inserted block in

[0063] BRIEF DESCRIPTION OF THE DRAWINGS​​​​​​​​

[0064] 1-top plate; 2-surrounding pressure stabilizing assembly; 3-second motor; 4-second adjusting member; 5-drilling fluid storage tank; 6-valve; 7-opening and closing valve; 8-regulating valve; 9-third pressure gauge; 10-second pressure gauge; 11-first pressure gauge; 12-overflow pressure gauge; 13-overflow flow gauge; 14-beaker; 15-second pipeline; 16-first pipeline; 17-third pipeline; 18-second coupling; 19-core sample; 20-surrounding pressure inner container; 21-bottom plate; 22-housing; 23-first motor; 24-first coupling; 25-first adjusting member; 26-hydraulic oil tank; 27-slotting insert block; G-slotting; H-sample deep hole; a-first communication port; b-second communication port; c-third communication port. DETAILED DESCRIPTION

[0065] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0066] A first aspect of the present application provides a device for evaluating original leakage pressure and leakage pressure after plugging in a laboratory, as shown in the accompanying drawings. Figure 1 The device for evaluating original leakage pressure and leakage pressure after plugging in a laboratory includes:

[0067] A pressure chamber assembly, in which a containing cavity for containing a core sample 19 is formed;

[0068] A surrounding pressure pipeline assembly, two ends of the surrounding pressure pipeline assembly are respectively connected to a hydraulic oil source and the containing cavity, and the surrounding pressure pipeline assembly is used to deliver hydraulic oil to the containing cavity;

[0069] A surrounding pressure inner container 20, which is arranged in the containing cavity and is used to be sleeved outside the core sample 19, and is used to apply a surrounding pressure to the core sample 19 through the hydraulic oil;

[0070] A simulated casing pipeline assembly, two ends of the simulated casing pipeline assembly are respectively connected to a drilling fluid source and a sample deep hole H of the core sample 19, and the simulated casing pipeline assembly is used to deliver drilling fluid to the sample deep hole H;

[0071] A slotting insert block 27, which is used to be inserted into the slotting G;

[0072] A controller, which is in communication connection with the surrounding pressure pipeline assembly and the simulated casing pipeline assembly, and is used to determine a leakage pressure array of the core sample 19, wherein the leakage pressure array includes original leakage pressure and leakage pressure after plugging.

[0073] Specifically, the core sample 19 in the embodiment can be a full-diameter core sample 19, i.e., a core taken from an oil (gas) layer by coring technology, which is not cut and split, and is a columnar core used for laboratory analysis and determination of relevant parameters. The full-diameter core sample 19 in the embodiment has a diameter of 100 mm and a height of 5 cm. A deep hole with a diameter ranging from 5 mm to 80 mm and a depth ranging from 0 to 4 cm is drilled in the center of the full-diameter core. The full-diameter core sample 19 has one slit G, which is distributed along the radial direction of the full-diameter core sample 19, and the slit G has a thickness of 1 mm and a depth equal to that of the sample deep hole H. Further, the core sample 19 can be alternatively accommodated in the accommodation cavity. The pressure chamber assembly is injected with hydraulic oil through the confining line assembly, so as to apply pressure to the confining liner 20 around the core sample 19 in the pressure chamber assembly, and then uniformly apply confining pressure to the outer peripheral wall of the core sample 19. Due to the confining pressure, the slit G on the core sample 19 will be closed, and drilling fluid is injected into the sample deep hole H of the core sample 19 through the simulation casing line assembly, while the pressure of the drilling fluid is uniformly increased. After the pressure of the drilling fluid is increased to a certain degree, the high-pressure drilling fluid exerts pressure on the hole wall of the sample deep hole H and opens the slit G on the core sample 19, so that the drilling fluid can flow out of the slit G of the core sample 19, i.e., the drilling fluid loss is simulated.

[0074] When the original loss pressure is evaluated using the original loss pressure and the loss pressure after plugging indoor evaluation device in the embodiment, the core sample 19 is placed in the accommodation cavity, and then the confining line assembly is controlled to inject hydraulic oil into the pressure chamber assembly, so as to apply pressure to the confining liner 20 around the core sample 19 in the pressure chamber assembly, and then uniformly apply confining pressure to the outer peripheral wall of the core sample 19 to close the slit G on the core sample 19 (at this time, the closed state of the slit G is the first closed state). Then, the drilling fluid is injected into the sample deep hole H of the core sample 19 through the simulation casing line assembly, while the pressure of the drilling fluid is uniformly increased. After the pressure of the drilling fluid is increased to a first pressure, the high-pressure drilling fluid exerts pressure (i.e., the first pressure) on the hole wall of the sample deep hole H, which can open the slit G on the core sample 19, so that the drilling fluid can flow out of the slit G of the core sample 19. The controller obtains the first pressure of the drilling fluid at this time, which is the original loss pressure. After the controller determines the original loss pressure, the confining line assembly and the simulation casing line assembly are both stopped.

[0075] When the post-plugging loss pressure is evaluated by using the original loss pressure and post-plugging loss pressure indoor evaluation device in the embodiment, the slot insertion block 27 is inserted into the slot G, and then the combination of the core sample 19 and the slot insertion block 27 is placed in the containing cavity. Then, the confining pressure pipeline assembly is controlled to inject hydraulic oil into the pressure chamber assembly, so as to apply pressure to the confining pressure liner 20 around the core sample 19 in the pressure chamber assembly, and then the confining pressure is uniformly applied to the outer peripheral wall of the core sample 19 to close the slot G on the combination of the core sample 19 and the slot insertion block 27 (at this time, the closed state of the slot G is the second closed state). Then, the simulated casing pipeline assembly is controlled to inject drilling fluid into the sample deep hole H of the core sample 19, and the pressure of the drilling fluid is uniformly increased. After the pressure of the drilling fluid is increased to the second pressure, the high-pressure drilling fluid can open the slot G on the core sample 19, so that the drilling fluid can flow out of the slot G of the core sample 19. The second pressure of the drilling fluid at this time is obtained by the controller, and the second pressure is the post-plugging loss pressure. Further, considering that the original loss pressure and post-plugging loss pressure indoor evaluation device needs to simulate the core sample 19 under different depth conditions, different lithology, different interfaces, different interlayers and different pore conditions according to actual needs, a plurality of core samples 19 can be used for multiple experimental simulations according to needs to further ensure the evaluation accuracy of the loss pressure array.

[0076] The original loss pressure and post-plugging loss pressure indoor evaluation device in the embodiment has the advantages of simple structure, which can evaluate the original loss pressure of the core sample 19 by setting the pressure chamber assembly, the confining pressure pipeline assembly, the confining pressure liner 20, the simulated casing pipeline assembly and the controller. The post-plugging loss pressure of the core sample 19 can be evaluated by increasing the slot insertion block 27 on the basis of the above components. The evaluation accuracy of the loss pressure array is ensured, and the operation is simple and fast, which reduces the evaluation difficulty of the loss pressure array and is beneficial to improving the simulation effect of the drilling fluid loss pressure measurement under different conditions.

[0077] Further, referring to Figures 7 to 14In this embodiment, the core sample 19 can be of various types, such as conventional cores, interface-type cores, fracture-vuggy cores, and interlayer-type cores. Therefore, the indoor evaluation device for original leakage pressure and post-plugging leakage pressure can simulate experiments on cores with different formation conditions at different depths, different lithologies, and different interfaces, interlayers, and pore conditions. This introduces more formation parameters into the measurement of drilling fluid leakage pressure, thereby improving the accuracy of the simulation experiment. Furthermore, those skilled in the art will understand that the method of applying confining pressure to the core sample 19 in this embodiment is not limited to injecting hydraulic oil into the pressure chamber assembly through the confining pressure pipeline assembly. It can also be achieved by injecting water or other liquids. The drilling fluid can also be of various types, such as emulsified drilling agents, water-based drilling agents, etc.

[0078] In one embodiment of this application, the confining pressure pipeline assembly includes:

[0079] The first pipeline 16 is connected between the hydraulic oil source and the receiving cavity;

[0080] The first adjusting element 25 is disposed on the first pipeline 16 and is used to adjust the pressure of the hydraulic oil.

[0081] Specifically, such as Figure 2 As shown, the first pipeline 16 is connected to the confining pressure pipeline interface of the shell 22 (the confining pressure pipeline interface of the shell 22 is connected to the receiving cavity). The first pipeline 16 introduces hydraulic oil from the hydraulic oil source into the receiving cavity of the pressure chamber assembly. After the first adjusting component 25 adjusts the pressure of the hydraulic oil, the hydraulic oil will squeeze the confining pressure inner bladder 20, thereby applying confining pressure to the outer peripheral wall of the core sample 19 until the cut G is closed. The first regulating component 25 can be a first high-pressure pump, and the hydraulic oil source can be a hydraulic oil tank 26. The confining pressure pipeline assembly also includes a confining pressure stabilizing component 2, valves 6, and a first pressure gauge 11, all of which are communicatively connected to the controller. Hydraulic oil, after being pressurized by the first high-pressure pump, enters the receiving cavity via the first pipeline 16. Valves 6 are installed on the first pipeline 16 and are used to control the opening and closing of the first pipeline 16. The first pressure gauge 11 is installed on the first pipeline 16 and is used to detect and display the pressure of the hydraulic oil in the first pipeline 16. The confining pressure stabilizing component 2 includes a hydraulic pipeline connected to the first pipeline 16, on which multiple pressure control valves 6 are installed (in this embodiment, multiple pressure control valves 6 are communicatively connected to the controller). The controller can adjust the actual pressure in the first pipeline 16 by adjusting the pressure control valves 6, and stabilize the pressure. This configuration further improves the accuracy of the simulation of the original leakage pressure and the leakage pressure after plugging in the indoor evaluation device, and facilitates operation by experimental personnel.

[0082] Furthermore, the confining pressure pipeline assembly also includes a first motor 23 and a first coupling 24. The first motor 23 is connected to the first adjusting member 25 through the first coupling 24. The suction port of the first adjusting member 25 is connected to the hydraulic oil tank 26, and the output port of the first adjusting member 25 is connected to the confining pressure stabilizing component 2.

[0083] In one embodiment of this application, the simulated casing pipeline assembly includes:

[0084] The second pipeline 15 is connected between the drilling fluid source and the deep hole H of the sample.

[0085] The second regulating component 4 is installed on the second pipeline 15 and is used to regulate the pressure of the drilling fluid.

[0086] Specifically, such as Figure 2 As shown, the second regulating component 4 can introduce drilling fluid from the drilling fluid source into the sample depth H of the core sample 19 through the second pipeline 15. After the drilling fluid pressure is increased to a certain level by the second regulating component 4, the drilling fluid with sufficiently high pressure can open the cut G on the core sample 19, so that the drilling fluid can flow out from the cut G of the core sample 19 to simulate drilling fluid loss. In this embodiment, the second regulating component 4 can be selected as a second high-pressure pump, and the drilling fluid source can be selected as a drilling fluid storage tank 5. The drilling fluid storage tank 5 can be filled with drilling fluid of different openings to meet different formation depth conditions. The simulated casing pipeline assembly also includes a second pressure gauge 10, a third pressure gauge 9, and an opening / closing valve 7, all communicatively connected to the controller and located downstream of the second regulating element 4. The second pressure gauge 10, the third pressure gauge 9, and the opening / closing valve 7 are all mounted on the second pipeline 15, which connects to the simulated casing pipeline assembly interface on the top plate 1 of the pressure chamber assembly. The third pressure gauge 9 and the second pressure gauge 10 are located upstream and downstream of the opening / closing valve 7, respectively. The third pressure gauge 9 detects and displays the pressure of the drilling fluid flowing through its location, while the second pressure gauge 10 detects and displays the pressure of the drilling fluid flowing through its location. After being pressurized by the second high-pressure pump, the drilling fluid sequentially enters the sample depth hole H of the core sample 19 via the third pressure gauge 9, the opening / closing valve 7, and the second pressure gauge 10. This configuration helps to further improve the accuracy of the simulation of the original leakage pressure and the leakage pressure after plugging within the chamber evaluation device.

[0087] Furthermore, the simulated casing pipeline assembly also includes a second motor 3 and a second coupling 18. The second motor 3 is connected to the second adjusting member 4 through the second coupling 18. The inlet of the second adjusting member 4 is connected to the drilling fluid storage tank 5. The pressure of the drilling fluid in the second pipeline 15 is generated by the second motor 3 driving the second adjusting member 4. Adjusting the speed of the second motor 3 continuously increases the pressure of the drilling fluid.

[0088] In one embodiment of this application, such asFigures 1 to 6 As shown, the pressure chamber assembly comprises a top plate 1, a bottom plate 21, a shell 22, a first sealing rubber ring and a second sealing rubber ring, the top plate 1 and the bottom plate 21 are vertically spaced apart, the shell 22 is arranged between the top plate 1 and the bottom plate 21, and the two ends of the shell 22 are detachably connected with the top plate 1 and the bottom plate 21 respectively, the top plate 1, the bottom plate 21 and the shell 22 jointly enclose a containing cavity, the first sealing rubber ring is arranged between the top plate 1 and the confining pressure liner 20 and is used for sealing the gap between the top plate 1 and the confining pressure liner 20, and the second sealing rubber ring is arranged between the bottom plate 21 and the confining pressure liner 20 and is used for sealing the gap between the bottom plate 21 and the confining pressure liner 20.

[0089] Specifically, as shown in Figure 1 and Figure 4 , the shell 22 is centrally provided with a through hole with a diameter slightly larger than that of the full-diameter core sample 19, the confining pressure liner 20 is installed in the through hole by a clearance fit, the full-diameter core sample 19 is installed in the confining pressure liner 20, and the top plate 1 and the bottom plate 21 are respectively installed on the upper and lower parts of the shell 22 by bolt connection; the diameter of the first sealing rubber ring is between the diameter of the simulated sleeve pipe line interface on the top plate 1 and the diameter of the full-diameter core sample 19, and the second sealing rubber ring is located between the lower part of the shell 22 and the upper part of the bottom plate 21 and has a diameter larger than that of the upper through hole of the shell 22. The pressure chamber assembly is provided with a first communication port a in communication with the sample deep hole H, and a second communication port b and a third communication port c in communication with the hollow cavity and the liner opening respectively, the drilling fluid enters the sample deep hole H through the first communication port a to pressurize the core sample 19 to open the slit G, the hydraulic oil enters the containing cavity through the second communication port b to extrude the confining pressure liner 20, thereby simulating the confining pressure of the core, and after the slit G is opened by the pressure of the drilling fluid, the drilling fluid can flow out of the pressure chamber assembly through the slit G and the third communication port c. Through the above arrangement, the core sample 19 can be quickly replaced after the top plate 1 is removed, which is conducive to improving the experimental efficiency, and the sealing of the containing cavity of the pressure chamber assembly is not affected during multiple disassembly and assembly processes due to the arrangement of the first sealing rubber ring and the second sealing rubber ring.

[0090] In an embodiment of the present application, the horizontal section of the slit insertion block 27 is wedge-shaped.

[0091] Specifically, the size of the lost circulation pressure array is not only related to the form of the core sample 19 and the confining pressure of the core sample 19, but also affected by the opening degree of the slit G. In the present embodiment, as shown in Figure 15As shown, the slit-inserting block 27 is inserted into the slit G and can adjust the opening of the slit G, and the horizontal section of the slit-inserting block 27 is provided with a scale (such as 2mm, 3mm, 4mm or 5mm) for identifying the opening of the slit G. After the slit-inserting block 27 is inserted into the slit G by the experimenter, the quantitative adjustment of the opening of the slit G can be realized by adjusting the insertion depth of the slit-inserting block 27 in the slit G (the insertion depth of the slit-inserting block 27 in the slit G is proportional to the opening of the slit G), that is, the opening of the slit G can be changed and the slit G can be closed, and the opening of the slit G is consistent with a certain scale on the slit-inserting block 27, so that the leakage pressure measurement after the core sample 19 is plugged can be realized. Further, the material of the slit-inserting block 27 can be an elastic material, such as rubber.

[0092] In an embodiment of the present application, as shown in Figure 1 and Figure 3 As shown, the original leakage pressure and the leakage pressure after plugging indoor evaluation device further comprises a third pipeline 17, an overflow pressure gauge 12, an overflow flow gauge 13, a beaker 14 and an adjusting valve 8 for controlling the opening and closing of the third pipeline 17, the third pipeline 17 is connected between the beaker 14 and the slit G, the drilling fluid flows out of the slit G, passes through the confining pressure liner 20 interface and flows to the beaker 14 through the third pipeline 17, and the beaker 14 is used for collecting the drilling fluid flowing out of the slit G; the overflow pressure gauge 12 and the flow gauge are both installed on the third pipeline 17 and are used for detecting the pressure and the flow in the third pipeline 17, respectively.

[0093] In another embodiment of the present application, an original leakage pressure and leakage pressure after plugging indoor evaluation method is provided, which is applicable to the original leakage pressure and leakage pressure after plugging indoor evaluation device in the above-mentioned embodiments and comprises the following steps:

[0094] Step S101: controlling the confining pressure pipeline assembly to deliver hydraulic oil into the containing cavity, so as to apply a first confining pressure to the core sample 19 and make the slit G in a first closed state;

[0095] Step S102: controlling the simulated casing pipeline assembly to deliver drilling fluid with gradually increasing pressure to the sample deep hole H of the core sample 19;

[0096] Step S103: determining that the drilling fluid flows out of the slit G;

[0097] Step S104: obtaining the first pressure of the drilling fluid.

[0098] Specifically, the experimental personnel place the core sample 19 in the containing cavity (the confining pressure liner 20 is located outside the core sample 19), ensure that the opening of the slit G of the core sample 19 is aligned with the outlet of the confining pressure liner 20, and then control the shell 22 to start, the shell 22 drives the first adjusting member 25 to rotate through the first coupling 24, the first adjusting member 25 pressurizes the hydraulic oil in the hydraulic oil tank 26 and keeps the pressure stable; then the controller opens the valve 6, adjusts the confining pressure stabilizing assembly 2, so that the pressure of the first pressure gauge 11 reaches the opening condition, and the pressurized hydraulic oil is delivered from the first pipeline 16 to the part of the containing cavity between the shell 22 and the confining pressure liner 20, the above-mentioned pressurized hydraulic oil uniformly applies pressure to the confining pressure liner 20 on the outer circumferential side of the core sample 19, and then the first confining pressure is uniformly applied to the outer circumferential wall of the core sample 19 to close the slit G on the core sample 19 (at this time, the closing state of the slit G is the first closing state), the first confining pressure is the confining pressure that the core sample 19 receives when the slit G on the core sample 19 is in the first closing state;

[0099] Then the controller controls the second motor 3 to start, the second motor 3 drives the second adjusting member 4 to rotate through the second coupling 18, the second adjusting member 4 continuously pressurizes the drilling fluid in the drilling fluid storage tank 5, the opening and closing valve 7 and the adjusting valve 8 are opened, the pressurized drilling fluid is delivered from the second pipeline 15 to the sample deep hole H of the core sample 19, when the drilling fluid pressure reaches a certain condition, the slit G on the core sample 19 is opened, the drilling fluid flows out from the slit G and flows into the beaker 14 through the third pipeline 17, the overflow pressure gauge 12 measures the pressure of the drilling fluid in the third pipeline 17 and sends it to the controller, the pressure of the drilling fluid measured by the overflow pressure gauge 12 is the first pressure, that is, the original loss pressure.

[0100] Step S105: control the confining pressure pipeline assembly to stop delivering hydraulic oil into the containing cavity and control the simulated casing pipeline assembly to stop delivering drilling fluid into the sample deep hole H;

[0101] Step S106: insert the slit insertion block 27 into the slit G.

[0102] Specifically, the controller stops the confining pressure pipeline assembly and the simulated casing pipeline assembly after determining the first pressure, the experimental personnel insert the slit insertion block 27 into the slit G (the experimental personnel insert the slit insertion block 27 to an appropriate depth according to actual needs, so that the opening degree of the slit G is an appropriate opening degree), and then place the combination of the core sample 19 and the slit insertion block 27 in the containing cavity (the confining pressure liner 20 is located outside the combination of the core sample 19 and the slit insertion block 27), and the opening of the slit G of the core sample 19 is aligned with the outlet of the confining pressure liner 20.

[0103] Step S107: control the confining pressure pipeline assembly to deliver hydraulic oil into the containing cavity to exert a second confining pressure on the core sample 19 and make the slit G in a second closed state;

[0104] Step S108: control the simulated casing pipeline assembly to deliver drilling fluid again into the sample deep hole H of the core sample 19;

[0105] Step S109: determine that the drilling fluid flows out of the slit G again;

[0106] Step S110: obtain a second pressure of the drilling fluid;

[0107] Step S111: determine a leak-off pressure array according to the first pressure and the second pressure.

[0108] Specifically, the controller controls the shell 22 to start, the shell 22 drives the first adjusting part 25 to rotate through the first coupling 24, the first adjusting part 25 pressurizes the hydraulic oil in the hydraulic oil tank 26 and keeps the pressure stable; then the controller opens the valve 6, adjusts the confining pressure stabilizing assembly 2, so that the pressure of the first pressure gauge 11 reaches the opening condition, and the pressurized hydraulic oil is delivered from the first pipeline 16 to the part of the containing cavity between the shell 22 and the confining pressure inner container 20, the above-mentioned pressurized hydraulic oil uniformly exerts pressure on the confining pressure inner container 20 on the outer circumferential side of the core sample 19, thereby realizing uniform exertion of the second confining pressure on the outer circumferential wall of the core sample 19 to make the slit G on the core sample 19 closed (at this time, the closed state of the slit G is the second closed state), and the second confining pressure is the confining pressure that the core sample 19 receives when the slit G on the core sample 19 is in the second closed state;

[0109] Then the controller controls the second motor 3 to start, the second motor 3 drives the second adjusting part 4 to rotate through the second coupling 18, the second adjusting part 4 continuously pressurizes the drilling fluid in the drilling fluid storage tank 5, the opening and closing valve 7 and the adjusting valve 8 are opened, the pressurized drilling fluid is delivered into the sample deep hole H of the core sample 19 through the second pipeline 15, when the drilling fluid pressure reaches a certain condition, the slit G on the core sample 19 is opened again, the drilling fluid flows out of the slit G and flows into the beaker 14 through the third pipeline 17, the overflow pressure gauge 12 measures the pressure of the drilling fluid in the third pipeline 17 and sends it to the controller, the pressure of the drilling fluid measured by the overflow pressure gauge 12 is the second pressure, that is, the leak-off pressure after plugging, and the controller determines that the original leak-off pressure and the leak-off pressure after plugging together constitute the leak-off pressure array.

[0110] Further, the experimenter inserts the slit insertion block 27 into the slit G at different depths, and repeats steps S107-S111 to obtain the leak-off pressure after plugging at different slit G openings and draw a graph of the relationship between the leak-off pressure after plugging and the slit G opening.

[0111] In an embodiment of the present application, the original leakage pressure and the leakage pressure after plugging indoor evaluation further comprises a first adjusting member 25, and the original leakage pressure and the leakage pressure after plugging indoor evaluation method further comprises:

[0112] After controlling the confining pressure pipeline assembly to deliver hydraulic oil into the containing cavity, the first adjusting member 25 is controlled to adjust the pressure of the hydraulic oil to the first confining pressure, so that the slit G is in the first closed state; and,

[0113] After controlling the confining pressure pipeline assembly to deliver hydraulic oil into the containing cavity again, the first adjusting member 25 is controlled to adjust the pressure of the hydraulic oil to the second confining pressure, so that the slit G is in the second closed state.

[0114] Specifically, in step S101, the shell 22 is controlled to start, the shell 22 drives the first adjusting member 25 to rotate through the first coupling 24, and the first adjusting member 25 pressurizes the hydraulic oil in the hydraulic oil tank 26 until the first confining pressure, so that when the hydraulic oil tank 26 outputs the hydraulic oil with the first confining pressure into the containing cavity, the slit G can be in the first closed state.

[0115] Similarly, in step S107, the shell 22 is controlled to start, the shell 22 drives the first adjusting member 25 to rotate through the first coupling 24, and the first adjusting member 25 pressurizes the hydraulic oil in the hydraulic oil tank 26 until the second confining pressure, so that when the hydraulic oil tank 26 outputs the hydraulic oil with the second confining pressure into the containing cavity, the slit G can be in the second closed state.

[0116] In an embodiment of the present application, the second confining pressure and the first confining pressure are consistent, and the first confining pressure can be determined according to the following manner:

[0117]

[0118] (1)

[0120] wherein, is a first preset borehole stress; is a second preset borehole stress; is a third preset borehole stress; is a preset borehole shear stress; is a preset borehole radius; is a preset borehole pressure; is an angle of the core sample 19 in the cylindrical coordinate system; is a distance between the core sample 19 and the origin in the cylindrical coordinate system; is the first confining pressure.

[0121] Specifically, in actual situation, the confining pressure of the core is determined by the three-directional in-situ stress in the principal stress space, the inclination angle, the azimuth angle, the wellbore pressure and the wellbore radius in the underground condition. However, in the simulation experiment, the coordinate system of the principal stress space in the underground simulation condition needs to be converted into the coordinate system of the wellbore, that is, the wellbore three-directional stress (i.e. , , ) and the well surface shear stress of the core sample 19 in the wellbore coordinate system are calculated according to the three-directional in-situ stress (i.e. , , ) in the preset coordinate system of the principal stress space in the underground simulation condition, the inclination angle, the azimuth angle and the formula (2);

[0122] and then the first confining pressure of the core sample 19 in the cylindrical coordinate system is obtained by applying the wellbore three-directional stress, the well surface shear stress, the wellbore pressure, the wellbore radius and the formula (1).

[0123] wherein the formula (2) is:

[0124] (2)

[0125] Further,

[0126] (3)

[0127] wherein, is the first in-situ stress of the three-directional in-situ stress; is the second in-situ stress of the three-directional in-situ stress; is the third in-situ stress of the three-directional in-situ stress; is the inclination angle; is the azimuth angle.

[0128] In an embodiment of the present application, the determination of the drilling fluid flowing out of the slit G in step S103 or the determination of the drilling fluid flowing out of the slit G again in step S109 comprises:

[0129] acquiring the flow value of the drilling fluid at the output end of the slit G;

[0130] in the case that the flow value reaches the preset overflow flow value, determining that the drilling fluid flows out of the slit G of the core sample 19.

[0131] Specifically, as shown in Figure 1 and Figure 3 , the preset overflow flow value is selected as zero in the embodiment, and the overflow flow table 13 is arranged on the third pipeline 17, when the drilling fluid flows out of the slit G of the core sample 19, the overflow flow table 13 will generate a reading and send the reading result to the controller, and the controller can determine that the drilling fluid flows out of the slit G of the core sample 19.

[0132] In another embodiment of this application, determining in step S103 that drilling fluid flows out of the slot G or determining in step S109 that drilling fluid flows out of the slot G again includes:

[0133] Obtain the drilling fluid pressure value at the output end of the slot G;

[0134] When the pressure reaches the preset overflow pressure value, it is determined that the drilling fluid flows out from the cut G of the core sample 19.

[0135] Specifically, such as Figure 1 and Figure 3 As shown, in this embodiment, the preset overflow pressure value is set to zero, and an overflow pressure gauge 12 is set on the third pipeline 17. When the drilling fluid flows out from the cut G of the core sample 19, the overflow pressure gauge 12 generates a reading and sends the reading result to the controller. The controller can then determine that drilling fluid has flowed out from the cut G of the core sample 19.

[0136] Furthermore, in actual operation, it is confirmed that there is a time difference between the drilling fluid flowing out of the cut G of the core sample 19 and the recording of the current drilling fluid pressure as the leakage pressure. During this time difference, the second regulating element 4 continues to increase the drilling fluid pressure. Therefore, the pressure measured by the overflow pressure gauge 12 is usually greater than the actual leakage pressure (i.e., the first pressure is usually greater than the actual original leakage pressure, or the second pressure is usually greater than the actual post-plugging leakage pressure). The greater the difference between the pressure measured by the overflow pressure gauge 12 and the actual leakage pressure, the greater the flow rate and outflow pressure of the drilling fluid flowing out of the cut G. At this time, the situation where the pressure measured by the overflow pressure gauge 12 is greater than the actual leakage pressure can be determined by the readings of the overflow flow meter 13 and / or the overflow pressure gauge 12, thereby correcting the leakage pressure and further improving the accuracy of the indoor evaluation device for the original leakage pressure and the post-plugging leakage pressure.

[0137] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0138] In this application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixed", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrated; can be mechanical connection, can also be electrical connection or communication with each other; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0139] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

Claims

1. An indoor evaluation device for initial leakage pressure and leakage pressure after plugging, characterized in that, The indoor evaluation device for original leakage pressure and leakage pressure after plugging includes: Pressure chamber assembly, wherein a receiving cavity is formed within the pressure chamber assembly for accommodating a core sample (19); A confining pressure pipeline assembly, wherein both ends of the confining pressure pipeline assembly are connected to a hydraulic oil source and the receiving cavity, respectively, for supplying hydraulic oil into the receiving cavity; A confining pressure liner (20) is provided in the receiving cavity and is used to be sleeved on the outside of the core sample (19) for applying confining pressure to the core sample (19) through the hydraulic oil; A simulated casing pipeline assembly, the two ends of which are respectively connected to a drilling fluid source and a sample deep hole (H) of the core sample (19), for delivering drilling fluid to the sample deep hole (H). A slit insert (27) is used to insert into the slit (G); The controller is communicatively connected to the confining pressure pipeline assembly and the simulated casing pipeline assembly and is used to determine the leakage pressure array of the core sample (19), the leakage pressure array including the original leakage pressure and the leakage pressure after plugging.

2. The indoor evaluation device for original leakage pressure and leakage pressure after plugging as described in claim 1, characterized in that, The confining pressure pipeline assembly includes: The first pipeline (16) is connected between the hydraulic oil source and the receiving cavity; The first adjusting element (25) is disposed on the first pipeline (16) and is used to adjust the pressure of the hydraulic oil.

3. The indoor evaluation device for original leakage pressure and leakage pressure after plugging as described in claim 2, characterized in that, The simulated casing pipeline assembly includes: The second pipeline (15) is connected between the drilling fluid source and the deep hole (H) of the sample. The second regulating element (4) is installed on the second pipeline (15) and is used to regulate the pressure of the drilling fluid.

4. The indoor evaluation device for original leakage pressure and leakage pressure after plugging as described in claim 1, characterized in that, The pressure chamber assembly includes a top plate (1), a bottom plate (21), a housing (22), a first sealing ring, and a second sealing ring. The top plate (1) and the bottom plate (21) are arranged vertically at intervals. The housing (22) is disposed between the top plate (1) and the bottom plate (21), and both ends of the housing (22) are detachably connected to the top plate (1) and the bottom plate (21), respectively. The top plate (1), the bottom plate (21), and the housing (22) together enclose the receiving cavity. The first sealing ring is disposed between the top plate (1) and the confining pressure liner (20) and is used to seal the gap between the top plate (1) and the confining pressure liner (20). The second sealing ring is disposed between the bottom plate (21) and the confining pressure liner (20) and is used to seal the gap between the bottom plate (21) and the confining pressure liner (20).

5. The indoor evaluation device for original leakage pressure and leakage pressure after plugging as described in claim 1, characterized in that, The horizontal cross-section of the slit insertion block (27) is wedge-shaped.

6. A method for indoor evaluation of initial leakage pressure and leakage pressure after plugging, characterized in that, The indoor evaluation method for original leakage pressure and post-plugging leakage pressure is applicable to the indoor evaluation device for original leakage pressure and post-plugging leakage pressure according to any one of claims 1-5 and includes: The confining pressure pipeline assembly is controlled to deliver hydraulic oil into the receiving cavity to apply a first confining pressure to the core sample (19) and to put the cut (G) in a first closed state; The simulated casing pipeline assembly is controlled to deliver drilling fluid with gradually increasing pressure to the deep borehole (H) of the core sample (19). It is determined that the drilling fluid flows out of the cut (G); Obtain the first pressure of the drilling fluid; Control the confining pressure pipeline assembly to stop supplying the hydraulic oil into the receiving cavity and control the simulated casing pipeline assembly to stop supplying the drilling fluid into the deep hole (H) of the sample; Insert the slit insert block (27) into the slit (G); The confining pressure pipeline assembly is controlled to deliver the hydraulic oil into the receiving cavity to apply a second confining pressure to the core sample (19) and to put the cut (G) in a second closed state; The simulated casing pipeline assembly is controlled to deliver the drilling fluid to the sample deep hole (H) of the core sample (19) again; Determine that the drilling fluid flows out of the cut (G) again; Obtain the second pressure of the drilling fluid; The leakage pressure array is determined based on the first pressure and the second pressure.

7. The indoor evaluation method for original leakage pressure and leakage pressure after plugging as described in claim 6, characterized in that, The indoor evaluation of the original leakage pressure and the leakage pressure after plugging also includes a first adjustment element (25), and the indoor evaluation method of the original leakage pressure and the leakage pressure after plugging also includes: After controlling the confining pressure pipeline assembly to supply the hydraulic oil into the receiving cavity, the first regulating member (25) is controlled to adjust the pressure of the hydraulic oil to a first confining pressure, so that the cut (G) is in a first closed state; and, After the confining pressure pipeline assembly is controlled to supply the hydraulic oil into the receiving cavity again, the first regulating member (25) is controlled to adjust the pressure of the hydraulic oil to the second confining pressure so that the cut (G) is in the second closed state.

8. The indoor evaluation method for original leakage pressure and leakage pressure after plugging as described in claim 6, characterized in that, The first confining pressure is determined as follows: in, The first preset wellbore stress; The second preset wellbore stress; The third preset wellbore stress; To preset the well surface shear stress; Preset wellbore radius; Preset wellbore pressure; The angle of the core sample (19) in the cylindrical coordinate system; In the cylindrical coordinate system, the distance between the core sample (19) and the origin is given. This is the first confining pressure.

9. The indoor evaluation method for original leakage pressure and leakage pressure after plugging as described in claim 6, characterized in that, The determination that the drilling fluid flows out of the slot (G) or the determination that the drilling fluid flows out of the slot (G) again includes: Obtain the flow rate of the drilling fluid at the output end of the cut (G); When the flow rate reaches the preset overflow flow rate, it is determined that the drilling fluid flows out from the cut (G) of the core sample (19).

10. The indoor evaluation method for original leakage pressure and leakage pressure after plugging as described in claim 6, characterized in that, The determination that the drilling fluid flows out of the slot (G) or the determination that the drilling fluid flows out of the slot (G) again includes: Obtain the pressure value of the drilling fluid at the output end of the cut (G); When the pressure value reaches the preset overflow pressure value, it is determined that the drilling fluid flows out from the cut (G) of the core sample (19).

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