Double-layer filter for hydraulic fracturing test and integrated device

Abstract

The invention provides a double-layer filter for a hydraulic fracturing test, and belongs to the technical field of fracturing tests. The double-layer filter for the hydraulic fracturing test comprises an outer sleeve, a filter pipe and a filter element, the interior of the outer sleeve is of a hollow structure, and a water inlet channel, an inner cavity and a water outlet channel are arranged in the outer sleeve; a cavity is formed in the filter pipe, the two ends of the filter pipe are open, and filter holes communicated with the cavity are formed in the side wall of the filter pipe; the filter element is of a hollow structure, screening holes are formed in the side wall of the filter element, the inner diameter of the screening holes is smaller than that of the filter holes, and the first opening end of the filter pipe is connected with the filter element. The designed filter is of a double-layer structure, and a layer of filter pipe is additionally arranged between the outer sleeve and the filter element. And a plurality of pores are uniformly distributed on the side surfaces of the filter pipe and the filter element, so that the filter effect can be better improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fracturing test, in particular to a double-layer filter for hydraulic fracturing test. BACKGROUND

[0002] At present, the hydraulic fracturing (HF) in-situ stress measurement method is one of the important in-situ stress measurement technologies. As one of the most important physical properties of the solid earth crust, the in-situ stress property is an indispensable key basic data in the stages of national major infrastructure construction, key deep mineral resources and energy material exploration and development. Among all the in-situ stress measurement methods, the hydraulic fracturing test technology has become the most direct and effective method for determining the in-situ stress of rock mass recognized at home and abroad, with three characteristics and advantages of unlimited test section, no need for rock mechanics parameters in theoretical calculation, and relatively stable test results, and is widely used in the fields of tunnels, mines, energy development, etc.

[0003] M.K.Hubbert and D.G.Willis considered that the in-situ stress in deep underground is vertical and horizontal, emphasized that the two horizontal principal stresses are not necessarily equal and independent of the vertical stress, and not in hydrostatic pressure state, which are still the basis for us to understand hydraulic fracturing today(Hubbert and Willis, 1957; Kirsch, 1898). Haimson and Fairhurst(1967) pointed out that the fractures generated on the wellbore wall are related to three factors, ① crustal stress, ② the differential stress between the hydraulic fracturing fluid pressure and the pore water pressure; ③ the radial flow of rock permeability. B.C.Haimson and C.Fairhurst extended the poroelastic theory to the pressure borehole, and improved the basic theory of hydraulic fracturing in-situ stress measurement by extending the elastic model of M.K.Hubbert and D.G.Willis to consider the fluid permeation. In the early 1970s, American scholars B.C.Haimson and C.Fairhast proposed the theory of hydraulic fracturing in-situ stress measurement method and the corresponding measurement technology and process based on the hydraulic fracturing stimulation technology in the oil industry, which laid a solid foundation for the development of HF method. Since then, HF method has become a research hotspot. In 1970, the research group led by H.V.Schonfeldt and C.Fairhurst carried out the first real hydraulic fracturing stress measurement engineering practice in a shallow hole(including vertical and horizontal holes) of a granite rock mass in Minnesota, which verified the feasibility of hydraulic fracturing as a field measurement method(Schonfeldt and Fairhurst, 1972). In 1971, the branch of the United States Geological Survey financially supported the hydraulic fracturing in-situ stress measurement in Rangely Oilfield, Colorado, which was the earliest "deep hole hydraulic fracturing in-situ stress measurement" work and paved the way for the widespread acceptance of this method. Thus, the hydraulic fracturing method established its dominant position in the field of in-situ stress measurement, especially in the field of deep in-situ stress measurement. The hydraulic fracturing in-situ stress measurement in China began in the early 1980s, introduced from the United States through international cooperation by the Institute of Crustal Stress of China Earthquake Administration, and successfully carried out the first hydraulic fracturing in-situ stress measurement in Yixian County, Baoding City, Hebei Province in October 1980(Li Fangquan et al., 1980). Since then, Chen Quncei et al. carried out nonlinear research on the data processing of hydraulic fracturing in-situ stress measurement in multiple intersecting boreholes to solve the problems in the three-dimensional in-situ stress measurement method, and proposed a new theoretical model based on the minimum principal stress failure criterion.From 1992 to 1996, the representative work of the hydraulic fracturing method of in-situ stress testing technology in China is the Sino-Japanese cooperation project between the Institute of Crustal Stress of China Earthquake Administration and the Central Research Laboratories of Japan Electric Power, which realizes the miniaturization and lightness of the testing equipment, laying a solid foundation for the wide application of the hydraulic fracturing method of in-situ stress testing in China.

[0004] The hydraulic fracturing in-situ stress measuring equipment is currently mainly divided into five categories: (1) heavy cable type hydraulic fracturing in-situ stress measuring equipment, represented by MESY-SOLEXPERTS equipment of Switzerland; (2) light cable type hydraulic fracturing in-situ stress measuring equipment, mainly represented by shallow hole testing equipment manufactured by OYO Company of Japan and shallow hole testing equipment manufactured by CSIRO organization of Australia; (3) heavy cable type comprehensive testing equipment, represented by a new type of hydraulic fracturing testing equipment combining hydraulic fracturing testing with other geophysical logging equipment made by Professor Cornet of France and Professor Thiercelin of the United States; (4) deep well primary and secondary hole high-precision testing equipment, represented by BABHY testing equipment manufactured by Northeastern University of Japan; (5) detachable light type hydraulic fracturing testing equipment, represented by the drill pipe type hydraulic fracturing in-situ stress measuring equipment widely used in China.

[0005] The widely used measuring system in China is composed of six parts, a pressure fluid control system, a high-pressure water pump, a power system, a data recording system, a crossover packer and a high-pressure fluid conveying system. This measuring system is divided into two categories, one is for a shallow hole of 100 m, we can use drill pipes and high-pressure hoses to supply water to the packer and the fracturing section respectively to realize fracturing. The other equipment is for deep hole measurement above 100 m, we use a conversion valve to supply pressure liquid to the fracturing section and the packer respectively, and the testing system diagram is shown in Figure 15 、 Figure 16

[0006] The prior art in the above has the following defects: In the process of conventional hydraulic fracturing in-situ stress testing to drill pipe water injection, the high-pressure tape remaining in the drill pipe, impurities in the water and the test hole often enter the push-pull valve in the high-pressure waterway, which easily leads to blockage, the packer cannot be expanded or fixed on the hole wall and cannot be moved, resulting in that the in-situ stress experiment cannot be carried out, and the push-pull valve and the packer need to be cleaned again; this will lead to time-consuming and labor-consuming of the whole in-situ stress test and low efficiency. SUMMARY

[0007] In order to make up for the above shortcomings, the present application provides a double-layer filter for hydraulic fracturing testing, which aims to improve the problem that the high-pressure tape remaining in the drill pipe, impurities in the water and the test hole often enter the push-pull valve in the high-pressure waterway, leading to blockage.

[0008] ​The first aspect, the embodiment of the present application provides a kind of double-layer filter of hydraulic fracturing test, including outer sleeve, filter tube and filter core;

[0009] The inside of the outer sleeve is a hollow structure, the outer sleeve is provided with a water inlet channel, an inner cavity and a water outlet channel;The filter tube has a cavity inside, the two ends of the filter tube are open, and a filter hole is formed in the side wall of the filter tube, which is in communication with the inner cavity;

[0010] The filter core is a hollow structure, and a screening hole is formed in the side wall of the filter core, the inner diameter of the screening hole is smaller than the inner diameter of the filter hole, and the first open end of the filter tube is connected with the filter core.

[0011] In a preferred mode of the present application, one end of the outer sleeve is fixed with a pipe joint, one end of the pipe joint is connected with an inner tube, one end of the inner tube is connected with a drill rod joint, and one end of the drill rod joint is connected with a drill rod connecting piece.

[0012] In a preferred mode of the present application, the drill rod connecting piece is threadedly connected with the drill rod joint, a 2mm gap is reserved between the connecting end of the drill rod connecting piece and the drill rod joint, a tapered channel is arranged at one end of the drill rod connecting piece, a tapered counter-bore is arranged at one end of the drill rod joint, and the tapered counter-bore is communicated with a circular channel.

[0013] In a preferred mode of the present application, a water inlet channel A and a one-way valve channel are formed in the inner part of the pipe joint, a one-way valve is connected to the port of the one-way valve channel through a pipe joint, a flow guide channel is formed in the inner part of the inner tube, one end of the flow guide channel is communicated with the water inlet channel A, and the other end of the flow guide channel is communicated with the circular channel of the drill rod joint.

[0014] In a preferred mode of the present application, the water inlet channel, the inner cavity and the water outlet channel are arranged along the axis of the outer sleeve and connected in sequence; the diameter of the water outlet channel of the outer sleeve is smaller than the diameter of the inner cavity; during the test, the water inlet channel of the outer sleeve is communicated with the pipe joint, and the water outlet channel of the outer sleeve is connected with the ground stress testing device.

[0015] In a preferred mode of the present application, the one-way valve is threadedly connected with the pipe joint through a pipe joint, the outer periphery of the inner tube is wrapped with a protective sleeve, and the one-way valve is arranged in the protective sleeve; the water inlet channel and the water outlet channel of the outer sleeve are respectively connected to the two ends of the inner cavity, and the diameter of the water outlet channel of the outer sleeve is smaller than the diameter of the inner cavity.

[0016] In a preferred mode of the present application, the filter hole array is provided with a plurality of filter holes, the screen hole array is provided with a plurality of screen holes, the number of screen holes is equivalent to the number of filter holes, and the water flow from the water inlet channel of the outer sleeve flows into the inner cavity, and then flows into the filter core through the filter holes.

[0017] In a preferred mode of the present application, the outer diameter of the filter core is smaller than the inner diameter of the filter tube, and a containing space is provided between the outer wall of the filter core and the inner wall of the filter tube, thereby leaving a retention space for the precipitates of impurities, rust, etc.

[0018] In a preferred mode of the present application, an inner fastener is installed at the interface between the filter tube and the filter core, and the inner fastener is arranged in the outer sleeve to improve the firmness of the filter tube and the filter core.

[0019] In a preferred mode of the present application, the first open end of the filter tube is connected with the filter core through threads, one side of the filter core is fixed by abutting against the inner fastener, and the other end of the filter core is connected with the joint of the push-pull valve through threads; the screen hole is a pore with a diameter of 0.2 mm. The high-pressure flow that has been filtered by the filter tube is filtered again through the filter core and flows to the push-pull valve along the inside of the filter core.

[0020] In a preferred mode of the present application, the outer sleeve is provided with a filter tube at one end, the filter tube has a cavity, one end of the filter tube is open, and the other end is closed, the open end of the filter tube is inverted and fixed on the water outlet channel and the inner wall of the inner cavity, and a plurality of filter screen holes are arranged on the side wall of the filter tube and communicate with the inner cavity. The fracturing fluid flows into the inner cavity from the water inlet channel, and then flows out from the filter screen holes.

[0021] In the second aspect, the embodiments of the present application further provide an integrated device for water pressure fracturing test, which comprises the double-layer filter for water pressure fracturing test in any one of the above embodiments; and a fracturing pipe for preventing blockage in water pressure fracturing test, which comprises

[0022] The fracturing flower pipe is provided with a central channel, and a counterbore one-way high-pressure fluid output channel is arranged on the outer surface of the fracturing flower pipe and communicates with the central channel.

[0023] The connecting steel head is provided with two connecting steel heads, which are respectively sealed and connected with both ends of the fracturing flower pipe, the connecting steel head is provided with a seat sealing channel, the fracturing flower pipe is provided with a seat sealing through hole, the port of the seat sealing through hole is connected with the seat sealing channel, and the central part of the connecting steel head is provided with a fracturing channel, which communicates with the central channel.

[0024] Beneficial effects:

[0025] 1. The filter can realize the full filtration of high-pressure sealing tape, impurities and rust on the inner wall of the drill pipe in the fracturing fluid during the hydraulic fracturing in-situ stress test, so as to not affect the smooth progress of the in-situ stress test. The filter is designed as a double-layer structure, and a filter pipe is additionally arranged between the outer sleeve and the filter core. The filter pipe and the side surface of the filter core are both distributed with a large number of pores, which can better improve the filtering effect.

[0026] 2. Compared with the hydraulic fracturing in-situ stress test system without the filter, the filter can fully filter out the high-pressure sealing tape, impurities in the water and rust on the inner wall of the drill pipe during the hydraulic fracturing test of the drill pipe, so as to not affect the normal progress of the in-situ stress test. The filter is connected between the drill pipe and the push-pull valve, the filtering space is increased to add a double-layer filter pipe, and the filtering effect is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0028] Figure 1 is a double-layer filter structure schematic diagram of the hydraulic fracturing test provided by the embodiments of the present application;

[0029] Figure 2 is a filter pipe structure schematic diagram provided by the embodiments of the present application;

[0030] Figure 3 is a filter core structure schematic diagram provided by the embodiments of the present application;

[0031] Figure 4 is a pipe joint structure schematic diagram provided by the embodiments of the present application;

[0032] Figure 5 is a drill pipe joint structure schematic diagram provided by the embodiments of the present application;

[0033] Figure 6 is a drill pipe connecting piece structure schematic diagram provided by the embodiments of the present application;

[0034] Figure 7 is a double-layer filter three-dimensional structure schematic diagram provided by the embodiments of the present application;

[0035] Figure 8 is a double-layer filter three-dimensional perspective structure schematic diagram provided by the embodiments of the present application;

[0036] Figure 9 is a schematic diagram of a three-dimensional structure of the anti-blocking fracturing pipe provided by the embodiment of the present application;

[0037] Figure 10 is a schematic diagram of a three-dimensional structure provided by the embodiment of the present application;

[0038] Figure 11 is a schematic diagram of a three-dimensional structure of the fracturing flower pipe provided by the embodiment of the present application;

[0039] Figure 12 is a schematic diagram of a three-dimensional structure of the anti-backflow assembly provided by the embodiment of the present application;

[0040] Figure 13 is a schematic diagram of a three-dimensional structure of the limiting recess provided by the embodiment of the present application;

[0041] Figure 14 is a schematic diagram of a three-dimensional structure of the connection between the sealing ring and the compression spring provided by the embodiment of the present application;

[0042] Figure 15 is a schematic diagram of a double-loop test system structure of the water pressure fracturing in-situ stress measuring device provided by the embodiment of the present application;

[0043] Figure 16 is a schematic diagram of a single-loop test system structure of the water pressure fracturing in-situ stress measuring device provided by the embodiment of the present application.

[0044] In the figure: 1, drill pipe connecting piece; 2, drill pipe joint; 3, protective sleeve; 4, inner tube; 5, one-way valve; 6, pipe joint; 7, inner fastener; 8, outer sleeve; 9, filter tube; 10, filter core. DETAILED DESCRIPTION

[0045] In the present application, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connecting”, “fixing” and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature is "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature is "under", "below" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0047] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0048] Please refer to Figures 1-8 The present application provides a double-layer filter for hydraulic fracturing test, comprising an outer sleeve 8, a filter pipe 9 and a filter core 10.

[0049] The outer sleeve 8 is a hollow structure, and the outer sleeve 8 is internally provided with a water inlet channel, an inner cavity and a water outlet channel; the filter pipe 9 has a cavity inside, one end of the filter pipe 9 is open and the other end is closed, and a filter hole communicating with the inner cavity is formed in the side wall of the filter pipe 9; the filter pipe 9 is a hollow structure and has a plurality of small holes in the side wall of one end, and the outer wall of the end close to the inner fastener is a closed inner sleeve structure.

[0050] The filter core 10 is a hollow structure, and a screening hole is formed in the side wall of the filter core 10, the inner diameter of the screening hole is smaller than the inner diameter of the filter hole, and the open end of the filter pipe 9 is connected with the filter core 10.

[0051] In the specific embodiment of the present application, one end of the outer sleeve 8 is fixedly provided with a pipe joint 6, one end of the pipe joint 6 is connected with an inner pipe 4, one end of the inner pipe 4 is connected with a drill pipe joint 2, and one end of the drill pipe joint 2 is connected with a drill pipe connecting piece 1.

[0052] In the specific embodiment of the present application, the drill pipe connecting piece 1 is threadedly connected with the drill pipe joint 2, a 2mm gap is reserved at the connecting end of the drill pipe connecting piece 1 and the drill pipe joint 2, a tapered threaded head is arranged at one end of the drill pipe connecting piece 1, a tapered threaded butt joint hole is arranged at one end of the drill pipe joint 2, and the tapered threaded butt joint hole is communicated with a circular channel.

[0053] In a specific embodiment of the present invention, the pipe joint 6 has an inlet channel A and a one-way valve channel inside. The one-way valve channel port is connected to a one-way valve 5 through the pipe joint. The inner pipe 4 has a flow guiding channel inside. One end of the flow guiding channel is connected to the inlet channel A, and the other end of the flow guiding channel is connected to the circular channel of the drill pipe joint 2.

[0054] In a specific embodiment of the present invention, the water inlet channel, the inner cavity, and the water outlet channel are arranged along the axial direction of the outer sleeve 8 and connected end to end in sequence; the diameter of the water outlet channel of the outer sleeve 8 is smaller than the diameter of the inner cavity; during the test, the water inlet channel of the outer sleeve 8 is connected to the pipe joint 6, and the water outlet channel of the outer sleeve 8 is connected to the ground stress testing device.

[0055] In a specific embodiment of the present invention, the one-way valve 5 is connected to the pipe connector 6 by a pipe connector thread, the inner pipe 4 is wrapped with a protective outer sleeve 3, and the one-way valve 5 is disposed inside the protective outer sleeve 3; the water inlet channel and the water outlet channel of the outer sleeve 8 are respectively connected to the two ends of the inner cavity, and the diameter of the water outlet channel of the outer sleeve 8 is smaller than the diameter of the inner cavity.

[0056] In a specific embodiment of the present invention, the filter hole array is provided with multiple holes, and the sieving hole array is provided with multiple holes, the number of which is equivalent to the number of filter holes. Water flows into the inner cavity from the water inlet channel of the outer sleeve 8, and then flows into the filter element 10 from the inner cavity through the filter holes. The side of the filter tube 9 has many filter holes to filter the high-pressure fluid flowing into the space between the outer sleeve 8 and the filter tube 9 and guide it to the filter element 10 for further filtration.

[0057] In a specific embodiment of the present invention, the outer diameter of the filter element 10 is smaller than the inner diameter of the filter tube 9, and an accommodating space is provided between the outer wall of the filter element 10 and the inner wall of the filter tube 9, thereby leaving space for the retention of impurities, rust and other sediments after filtration.

[0058] In a specific embodiment of the present invention, an inner fastener 7 is installed at the joint between the filter tube 9 and the filter element 10. The inner fastener 7 is disposed inside the outer sleeve 8 to improve the firmness of the filter tube 9 and the filter element 10.

[0059] The outer sleeve 8 has threaded grooves at both ends. The outer diameter of the outer sleeve 8 is 70mm, and the inner diameter is 50mm. Inside the outer sleeve 8 are a filter tube 9 and a filter element 10, forming a dual filtration structure. One end of the outer sleeve 8 connects to the pipe connector 6 and is threadedly connected to the inner fastener 7 to provide additional tightening force and prevent loosening of critical components under high-frequency vibration or high-pressure impact. The outer side of the inner fastener 7 is threadedly connected to the outer sleeve 8 to provide additional tightening force and prevent loosening of critical components under high-frequency vibration or high-pressure impact. Six through holes are equally spaced on both sides to guide the high-pressure fluid from the connector to the space between the outer sleeve 8 and the filter tube 9 for filtration. The central through hole fits snugly against the filter tube 9, also serving a tightening function.

[0060] In a specific embodiment of the present invention, the open end of the filter tube 9 is threadedly connected to the filter element 10, the closed end of the filter element 10 is fixed by the inner fastener 7, and the other end of the filter element 10 is threadedly connected to the connector of the push-pull valve; the screening hole has a diameter of 0.2 mm. The high-pressure flow that has been filtered once by the filter tube 9 flows through the filter element 10 for another filtration and flows along the inside of the filter element 10 to the push-pull valve.

[0061] In a specific embodiment of the present invention, a filter tube 9 is installed at one end of the outer sleeve 8. The filter tube 9 has a cavity, one end of the filter tube 9 is open, and the other end is closed. The open end of the filter tube 9 is upside down on the water outlet channel and fixed to the inner wall of the inner cavity. Multiple filter screen holes communicating with the inner cavity are provided on the side wall of the filter tube 9. Fracturing fluid flows into the inner cavity from the water inlet channel and then flows out from the inner cavity through the filter screen holes.

[0062] To prevent impurities remaining inside the drill pipe, impurities in the fracturing fluid, and rust on the inner wall of the drill pipe from entering the hydraulic fracturing in-situ stress testing device and causing blockage of the water channels, multiple filtration gaps communicating with the cavity are provided on the side walls of the filter tube 9 and the filter element 10. To improve the filtration effect and achieve layered filtration, the diameter of the screening holes should be slightly smaller than the diameter of the filter holes on the filter tube 9. Furthermore, the outer diameter of the filter element 10 should be significantly smaller than the inner diameter of the filter tube 9 to ensure a certain distance between their side walls, thus providing space for impurities, rust, and other sediments in the filtered water.

[0063] The other end of the filter element 10 is welded to form a threaded tube, which is threadedly connected to the filter tube 9 and the push-pull valve connector, ensuring that the clean water that has undergone double filtration flows from the inner cavity of the filter element 10 into the push-pull valve. This threaded connection, together with the inner fastener 7, can simultaneously provide a two-sided fixation effect for the filter tube 9 and the filter element 10.

[0064] To facilitate installation and ensure sealing requirements, the threaded connections of the outer sleeve 8 with the connector and push-pull valve connector are all equipped with O-ring rubber seals with threaded grooves on one side of the connector.

[0065] like Figures 9 to 14 The present invention also provides an integrated device for hydraulic fracturing testing, comprising a double-layer filter for hydraulic fracturing testing as described in any one of the above embodiments; and an anti-clogging fracturing tube for hydraulic fracturing testing, comprising...

[0066] A fracturing tube 100 is provided, wherein a central channel 110 is provided inside the fracturing tube 100, and a countersunk one-way high-pressure fluid output channel 130 communicating with the central channel 110 is provided on the outer surface of the fracturing tube 100.

[0067] Two connecting steel heads 300 are provided, and the two connecting steel heads 300 are respectively sealed and connected to both ends of the fracturing tube 100. The connecting steel head 300 has a sealing channel 310, and the fracturing tube 100 has a sealing through hole. The port of the sealing through hole is connected to the sealing channel 310. The connecting steel head 300 has a fracturing channel 330 in the center, and the fracturing channel 330 is connected to the central channel 110.

[0068] An anti-backflow component 500 is also provided, which includes a countersunk screw A510 and a tension spring 530. The countersunk screw A510 is inserted into the countersunk hole unidirectional high-pressure fluid output channel 130. One end of the tension spring 530 is connected to the radial through hole at the end of the countersunk screw A510. The other end of the countersunk screw A510 is connected to a set screw 550 for adjusting the tension.

[0069] In a specific embodiment of the present invention, the countersunk unidirectional high-pressure fluid output channels 130 are arranged in pairs, including countersunk A and countersunk B. Countersunk A and countersunk B are symmetrically arranged on both sides of the central channel 110. The countersunk screw A510 is inserted into the countersunk A, and the countersunk screw B570 is inserted into the countersunk B. The end of the countersunk screw B570 has an internal thread hole, and the set screw 550 is connected to the internal thread hole. The countersunk screw A510 and the countersunk screw B570 are coaxially arranged.

[0070] Prolonged use can lead to wear on the sealing contact surface between the countersunk screw A510 and the countersunk hole unidirectional high-pressure fluid output channel 130, resulting in backflow prevention failure. Therefore, the following is a specific implementation plan for the anti-fracture tube of the water pressure fracturing test according to the attached figure:

[0071] Specifically, in a specific embodiment of the present invention, a limiting groove 190 is formed on the surface of the fracturing tube 100, a sealing ring 191 is slidably inserted in the limiting groove 190, a compression spring 193 is connected between the lower end of the sealing ring 191 and the bottom of the limiting groove 190, and the upper end of the sealing ring 191 abuts against the conical surface of the countersunk screw A510.

[0072] In a specific embodiment of the present invention, the limiting groove 190 is coaxially arranged with the countersunk one-way high-pressure fluid output channel 130. The limiting groove 190 is a blind groove. The lower end of the compression spring 193 is fixedly connected to the bottom of the limiting groove 190, and the upper end of the compression spring 193 is fixedly connected to the sealing ring 191. The conical surface of the countersunk screw A510 is provided with a sealing groove D, and the upper end of the sealing ring 191 is fitted into the sealing groove D.

[0073] After the inspection is completed, as the high-pressure liquid in the central channel 110 recedes, the countersunk screw A510 resets under the action of the tension spring 530. The upper end of the sealing ring 191 abuts against the end face of the countersunk screw A510, achieving a contact seal and effectively preventing backflow of external liquid. Furthermore, after the upper end of the sealing ring 191 wears, it is pushed outward by the elastic action of the compression spring 193 to compensate, always abutting against the conical surface of the countersunk screw A510, thus maintaining a constant sealing contact, extending the service life of the equipment, reducing maintenance costs, and effectively avoiding backflow caused by airtightness failure due to wear.

[0074] The working principle of the double-layer filter for the hydraulic fracturing test is as follows: When applying the filter for in-situ stress testing using the hydraulic fracturing method in this example, the water inlet channel of the outer sleeve 8 is connected to the drill rod through the drill rod connector 1, and the water outlet channel of the outer sleeve 8 is connected to the upper end of the hydraulic fracturing push-pull valve; one end of the filter tube 9 is threadedly connected to the filter element 10 and fits into the push-pull valve connector; the outer sleeve 8 is connected to the pipe connector 6 and the inner fastener 7, and the water outlet channel of the filter element 10 is connected to the push-pull valve connector. High-pressure water flows from the drill rod into the drill rod connector 1, the drill rod connector 2, and the inner cavity of the inner tube 4 in sequence, and then flows into the water inlet channel of the pipe connector 6, the through hole of the inner fastener 7, and the inner cavity of the outer sleeve 8. In the inner cavity of the outer protective sleeve, the water flows into its inner cavity through the filter hole of the filter tube 9. At this time, impurities in the water and large particles with a diameter greater than 1mm, such as rust on the inner wall of the drill rod, are fully filtered out by the filter hole and remain in the cavity of the outer protective sleeve. The filtered water flows into the inner cavity of filter element 10 through the filter holes, which have a diameter of 0.2 mm. These filter holes can further filter out finer impurities, improving the cleanliness of the water. After secondary filtration, the water flows from the outlet channel of filter element 10 to the connector of the push-pull valve for further stress testing.

[0075] It should be noted that the specific model and specifications of the filter element 10 and the one-way valve 5 need to be selected and determined according to the actual specifications of the device. The specific selection calculation method adopts the existing technology in this field, so it will not be described in detail.

[0076] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

Claims

1. A double-layer filter for water pressure fracturing test, characterized in that, include The outer sleeve (8) has a hollow structure inside and contains an inlet channel, an inner cavity and an outlet channel. The filter tube (9) has a cavity inside, and the filter tube (9) has openings at both ends. The filter tube (9) has filter holes on its side wall that communicate with the cavity. The filter element (10) is hollow and has a sieving hole on its side wall. The inner diameter of the sieving hole is smaller than the inner diameter of the filter hole. The first open end of the filter tube (9) is connected to the filter element (10).

2. The dual-layer filter for water pressure fracturing test according to claim 1, characterized in that, One end of the outer sleeve (8) is fixed with a pipe connector (6), one end of the pipe connector (6) is connected to an inner tube (4), one end of the inner tube (4) is connected to a drill pipe connector (2), and one end of the drill pipe connector (2) is connected to a drill pipe connector (1).

3. A double-layer filter for water pressure fracturing test according to claim 2, characterized in that, The drill rod connector (1) is threadedly connected to the drill rod joint (2). The connection end of the drill rod connector (1) and the drill rod joint (2) is reserved with a 2mm gap. One end of the drill rod connector (1) is provided with a tapered channel, and one end of the drill rod joint (2) is provided with a tapered mating groove. The tapered mating groove is connected to a circular channel.

4. A double-layer filter for water pressure fracturing test according to claim 2, characterized in that, The pipe joint (6) has an inlet channel A and a one-way valve channel inside. The one-way valve channel is connected to a one-way valve (5). The inner pipe (4) has a flow guide channel inside. One end of the flow guide channel is connected to the inlet channel A, and the other end of the flow guide channel is connected to the circular channel of the drill pipe joint (2).

5. A dual-layer filter for water pressure fracturing test according to claim 4, characterized in that, The water inlet channel, inner cavity, and water outlet channel are arranged along the axial direction of the outer sleeve (8) and connected end to end in sequence; the diameter of the water outlet channel of the outer sleeve (8) is smaller than the diameter of the inner cavity; during the test, the water inlet channel of the outer sleeve (8) is connected to the pipe joint (6), and the water outlet channel of the outer sleeve (8) is connected to the ground stress testing device.

6. A dual-layer filter for water pressure fracturing test according to claim 4, characterized in that, The one-way valve (5) is connected to the pipe connector (6) by the pipe connector thread. The outer periphery of the inner pipe (4) is wrapped with a protective outer sleeve (3). The one-way valve (5) is located inside the protective outer sleeve (3). The water inlet channel and the water outlet channel of the outer sleeve (8) are respectively connected to the two ends of the inner cavity. The diameter of the water outlet channel of the outer sleeve (8) is smaller than the diameter of the inner cavity.

7. A dual-layer filter for water pressure fracturing test according to claim 1, characterized in that, The filter hole array is provided with multiple holes, and the sieve hole array is provided with multiple holes. The number of sieve holes is equivalent to that of filter holes. Water flows from the water inlet channel of the outer sleeve (8) into the inner cavity, and then flows from the inner cavity into the filter element (10) through the filter holes.

8. A dual-layer filter for water pressure fracturing test according to claim 1, characterized in that, The outer diameter of the filter element (10) is smaller than the inner diameter of the filter tube (9). There is a space between the outer wall of the filter element (10) and the inner wall of the filter tube (9) to provide a space for the retention of impurities, rust and other sediments after filtration.

9. A dual-layer filter for water pressure fracturing test according to claim 1, characterized in that, An inner fastener (7) is installed at the joint between the filter tube (9) and the filter element (10). The inner fastener (7) is located inside the outer sleeve (8) to improve the firmness of the filter tube (9) and the filter element (10).

10. An integrated device for hydraulic fracturing testing, characterized in that, include The dual-layer filter for the hydrostatic fracturing test as described in any one of claims 1-9; as well as The anti-plugging fracturing tube for hydraulic fracturing testing is characterized by comprising: A fracturing tube (100) is provided with a central channel (110) inside the fracturing tube (100) and a countersunk one-way high-pressure fluid output channel (130) communicating with the central channel (110) is provided on the outer surface of the fracturing tube (100); Two connecting steel heads (300) are provided, and the two connecting steel heads (300) are respectively sealed and connected to both ends of the fracturing tube (100). The connecting steel head (300) has a sealing channel (310), and the fracturing tube (100) has a sealing through hole. The port of the sealing through hole is connected to the sealing channel (310). A fracturing channel (330) is provided in the center of the connecting steel head (300), and the fracturing channel (330) is connected to the central channel (110).

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