Rock mass hydraulic fracturing test high-strength bridging type packer and integrated device

Abstract

The invention provides a rock mass hydraulic fracturing test high-strength bridging type packer and an integrated device, and belongs to the technical field of in-situ stress measurement. The high-strength bridging type packer for the hydraulic fracturing test of the rock mass comprises a fracturing floral tube, a packer body and a central tube. The end part of the fracturing floral tube is connected with a steel head, the steel head is provided with a setting channel, and the steel head is hollow to form a fracturing channel; the steel head plug is arranged at one end, close to the central pipe plug, of the lower packer; the middle part of the central pipe is arranged in an inner cavity of the packer; the fracturing section water inlet hole is communicated with the setting channel through an internal pipeline, the setting channel is in threaded connection with the packer, and the space between the packer and the center pipe serves as a packer channel. The device is simple in structure and convenient to assemble, and testing section sealing of hydraulic fracturing in-situ stress measurement in the middle-diameter drill hole is achieved through the steel head, the upper packer, the center pipe, the steel head plug, the lower packer and the center pipe plug.

Description

Technical Field

[0001] The present application relates to the field of in-situ stress measurement, and in particular to a high-strength straddle-type packer and an integrated device for rock mass hydraulic fracturing testing. Background Art

[0002] At present, the hydraulic fracturing (HF) in-situ stress measurement method is one of the most important geostress measurement technologies. As one of the most important physical properties of the solid crust, geostress attributes are essential basic data for the construction of major national infrastructure, key deep mineral resources, and the exploration and development of energy materials. Among all geostress measurement methods, hydraulic fracturing testing technology has become the most direct and effective method for determining rock mass geostress with its three major characteristics and advantages: the test section is not limited by depth, the theoretical calculation does not require the participation of rock mechanical parameters, and the test results are relatively stable. It has become recognized at home and abroad as the most direct and effective method for determining rock mass geostress, and is widely used in tunnels, mines, energy development and other fields.

[0003] MK Hubbert and D.G. Willis believed that deep underground geostress is both vertical and horizontal, emphasizing that the two horizontal principal stresses are not necessarily equal and are independent of the vertical stress, rather than being in a hydrostatic state. These theoretical insights and elastic mechanics models remain the foundation of our understanding of hydraulic fracturing today (Hubbert and Willis, 1957; Kirsch, 1898). Haimson and Fairhurst (1967) pointed out that cracks in well walls are related to three factors: 1) crustal stress, 2) the differential stress between the hydraulic fracturing fluid pressure and the pore water pressure, and 3) the radial flow rate of rock mass infiltration. BC Haimson and C. Fairhurst extended the poroelastic theory to pressure-bearing boreholes and generalized the elastic model of MK Hubbert and D.G. Willis to consider fluid penetration, thus refining the basic theory of geostress testing for hydraulic fracturing. In the early 1970s, American scholars B.C. Haimson and C. Fairhurst, drawing on hydraulic fracturing production stimulation techniques in the petroleum industry, proposed the theory of in-situ hydraulic fracturing stress measurement, along with the corresponding measurement techniques and procedures. Their work laid a solid foundation for the development of the HF method, which has since become a research hotspot. In 1970, a research team led by H.V. Schonfeldt and C. Fairhurst conducted the first real hydraulic fracturing stress measurement engineering practice in shallow boreholes (including vertical and horizontal holes) in an underground granite rock mass in Minnesota. This experiment verified the feasibility of hydraulic fracturing as a field measurement method (Schonfeldt and Fairhurst, 1972). In 1971, a branch of the United States Geological Survey financially supported hydraulic fracturing stress measurement in the Rangely oil field in Colorado. This was the first "deephole hydraulic fracturing stress measurement" and paved the way for the widespread acceptance of this method. As a result, hydraulic fracturing has established its dominant position in geostress testing, particularly in deep geostress testing. Hydraulic fracturing geostress measurement in my country began in the early 1980s, when it was introduced from the United States by the Institute of Crustal Stress of the China Earthquake Administration through international collaboration. In October 1980, my country successfully conducted the first in situ stress measurement using hydraulic fracturing in Yi County, Baoding City, Hebei Province (Li Fangquan et al., 1980). Subsequently, Chen Qunzhe et al., addressing the challenges of three-dimensional geostress measurement using hydraulic fracturing, conducted nonlinear research on data processing using multiple intersecting boreholes for hydraulic fracturing stress measurement and proposed a new theoretical model based on the minimum principal stress failure criterion.From 1992 to 1996, the most representative work in my country on hydraulic fracturing ground stress testing technology was the Sino-Japanese cooperation project between the Institute of Crustal Stress of the China Earthquake Administration and the Central Research Institute of Electric Power Research Institutes of Japan, which achieved the miniaturization and lightweight of the testing equipment, laying a solid foundation for the widespread application of hydraulic fracturing ground stress testing methods in my country.

[0004] At present, hydraulic fracturing in-situ stress measurement equipment is mainly divided into five categories: (1) heavy-duty cable-type hydraulic fracturing in-situ stress measurement equipment, represented by the Swiss MESY-SOLEXPERTS equipment; (2) lightweight cable-type hydraulic fracturing in-situ stress measurement equipment, mainly represented by the shallow hole test equipment manufactured by Japan's OYO company and the shallow hole test equipment manufactured by Australia's CSIRO organization; (3) heavy-duty cable-type comprehensive test equipment, represented by the new hydraulic fracturing test equipment made by Professor Cornet of France and Professor Thiercelin of the United States that combines hydraulic fracturing testing with other geophysical logging equipment; (4) deep well mother-and-child hole high-precision test equipment, represented by the BABHY test equipment manufactured by Tohoku University of Japan; (5) detachable lightweight hydraulic fracturing test equipment, represented by the drill pipe hydraulic fracturing in-situ stress measurement equipment widely used in China.

[0005] The measurement system widely used in China consists of six parts: pressure fluid control system, high-pressure water pump, power system, data recording system, jumper packer and high-pressure fluid delivery system. This measurement system is divided into two categories. One is for shallow holes of 100m, we can use drill pipe and high-pressure hose to supply water to the packer and fracturing section respectively to achieve fracturing. The other equipment is for deep hole measurement over 100m, we use a conversion valve to supply pressure liquid to the fracturing section and packer respectively. The test system diagram is as follows Figure 12 、 Figure 13 As shown;

[0006] The previous analysis shows that for large-diameter boreholes, the test section length should be 6 to 7 times the borehole diameter, according to the International Society for Rock Mechanics. For conventional domestic 76mm or 94mm geological exploration boreholes, plus the approximately 1.0m length of the packer, the length of the intact rock mass in the borehole is at least 245.6cm to 256.4cm. The designed diameters of 70mm and 90mm packers are slightly smaller than the conventional 76mm and 94mm packers in China. After expansion, the packers just meet the test requirements. Therefore, these two diameters of packers have a wide range of applications in domestic hydraulic fracturing testing. The development of these two diameters of in-situ stress testing equipment is of great significance for promoting in-situ stress measurement in hydraulic fracturing and promoting the popularization and promotion of existing technologies.

[0007] The above-mentioned existing technical solutions have the following defects: since the diameters of the drill pipes, high-pressure hoses and other equipment used in conventional hydraulic fracturing in-situ stress testing are too large, the surplus space cannot be fully utilized to implement the hydraulic fracturing in-situ stress measurement solution in medium-diameter boreholes. Summary of the Invention

[0008] In order to make up for the above shortcomings, the present application provides a high-strength straddle-type packer for rock hydraulic fracturing testing, which aims to improve the problem of fully utilizing surplus space to realize the in-situ stress measurement scheme of hydraulic fracturing in medium-diameter boreholes.

[0009] In a first aspect, an embodiment of the present application provides a high-strength straddle-type packer for rock mass hydraulic fracturing testing, comprising a fracturing flower pipe, a packer, and a central pipe;

[0010] The end of the fracturing pipe is connected to a steel head, and the steel head is provided with a sealing channel, and the steel head is hollow to form a fracturing channel; the packer includes an upper packer and a lower packer, one end of the upper packer is directly connected to one end of the fracturing pipe, and one end of the lower packer is threadedly connected to the steel head, and the upper and lower packers are both expandable sealing rubber tubes, and the end of the upper packer is provided with a connecting thread for easy connection with the steel head, and the middle part of the upper packer is an expansion sealing section, and a steel sheet is embedded in the expansion sealing section, and the steel sheet is arranged inside it to effectively enhance the strength; during the hydraulic fracturing in-situ stress test, high-pressure fluid enters the expansion sealing section through the push-pull valve connecting pipe and the steel head to expand it and make it fit against the hole wall, and the sealing requirement of the test end is achieved through the cooperation of the upper packer and the lower packer;

[0011] The center pipe includes a first pipe body and a second pipe body, the first pipe body is inserted in the upper packer, and the second pipe body is inserted in the lower packer. The other end of the first pipe body is threadedly connected to the connecting pipe of the push-pull valve, and the other end of the second pipe body is threadedly connected to the center pipe plug. The surface of the second pipe body is provided with a steel head plug, and the steel head plug is arranged at one end of the lower packer close to the center pipe plug; the middle part of the center pipe is placed in the inner cavity of the packer, forming the expansion sealing section of the packer, and the inner cavity of the center pipe serves as a fracturing channel to transport high-pressure fluid to the fracturing pipe; the water inlet hole of the fracturing section is connected to the seat sealing channel through an internal pipeline, and the seat sealing channel is threadedly connected to the packer and makes the space between the packer and the center pipe serve as the packer channel.

[0012] In a preferred embodiment of the present invention, two steel heads are provided, and the two steel heads are sealed and docked with the two ends of the fracturing flower tube respectively. The steel head is provided with a sealing channel, and the fracturing flower tube is provided with a sealing through-hole. The port of the sealing through-hole is docked with the sealing channel, and a fracturing channel is provided in the center of the steel head.

[0013] In a preferred mode of the present application, the end of the fracturing flower pipe is provided with a sealing groove A, and the end of the steel head is provided with a convex head for clamping the sealing groove A; the inner wall of the fracturing channel is provided with a sealing groove C, and a rubber sealing ring C is clamped in the sealing groove C.

[0014] In a preferred mode of the present application, the outer surface of the convex head is provided with a sealing groove A, and a rubber sealing ring A is clamped in the sealing groove A; the inner wall of the convex head is provided with a sealing groove B, and a rubber sealing ring B is clamped in the sealing groove B; the rubber sealing ring A is in sealing contact with the rubber sealing ring B to seal the sealing groove A.

[0015] In a preferred mode of the present application, the center pipe plug is located at the lower end of the steel head plug, one end of the center pipe plug is directly connected with the steel head plug and is sealed by a sealing ring in a sealing groove, and the inner hole of the center pipe plug is threadedly connected with the second pipe body to block the fracturing channel.

[0016] In a preferred mode of the present application, one end of the upper packer is provided with a connecting thread, and both ends of the lower packer are provided with connecting threads; the upper packer and the lower packer are completely identical in structure, and the thread connection between the upper packer and the steel head is changed to direct adhesion for easy installation, that is, the internal thread of the upper packer at this position is removed.

[0017] In a preferred mode of the present application, both ends of the steel head are provided with thread grooves, respectively connected with a push-pull valve connecting pipe and the upper packer; the left end of the steel head is connected with the push-pull valve connecting pipe, and four seat sealing channels are provided in the steel head and connected with the through holes of the push-pull valve connecting pipe in correspondence. The water inlet hole of the fracturing section is connected with the fracturing channel of the steel head through an internal pipeline, the seat sealing channel of the steel head is threadedly connected with the packer, and the space between the packer and the center pipe serves as a packer channel.

[0018] In a preferred mode of the present application, both ends of the center pipe are provided with threads, the outermost ends are respectively threadedly connected with the connecting pipe of the push-pull valve and the center pipe plug, and the inner side is respectively threadedly connected with the fracturing flower pipe, so as to connect the upper packer and the lower packer through the fracturing flower pipe, realize the cross connection of the upper and lower packers, and the space between the center pipe and the packer serves as a packer channel. An O-shaped rubber sealing ring is arranged in the connecting groove of the center pipe to achieve the sealing effect of the thread connection end face.

[0019] In a preferred mode of the present application, the steel head plug is located between the lower packer and the center pipe plug, the steel head plug is threadedly connected with the lower packer, and is respectively threadedly connected with the O-shaped rubber sealing ring in the groove to achieve the sealing effect of the thread connection end face, so as to block the seat sealing channel at this position.

[0020] In a preferred embodiment of the present invention, rubber sealing rings are respectively provided at the steel head connection groove and the packer connection groove to achieve the function of sealing the threaded connection end face.

[0021] In a second aspect, an embodiment of the present invention further provides an integrated device for hydraulic fracturing testing, comprising a double-layer filter for hydraulic fracturing testing as described above; and an anti-blocking fracturing pipe for hydraulic fracturing testing, comprising

[0022] A fracturing flower tube, wherein a central channel is opened in the fracturing flower tube, and a countersunk one-way high-pressure fluid output channel connected to the central channel is opened on the outer surface of the fracturing flower tube;

[0023] Connecting steel heads, two of which are provided, and the two connecting steel heads are respectively sealed and docked with the two ends of the fracturing flower tube, the connecting steel head is provided with a sealing channel, the fracturing flower tube is provided with a sealing through-hole, the port of the sealing through-hole is docked with the sealing channel, and a fracturing channel is provided in the center of the connecting steel head, and the fracturing channel is connected with the central channel.

[0024] Beneficial effects:

[0025] 1. The present invention realizes an in-situ stress measurement scheme for hydraulic fracturing in medium-diameter boreholes by optimizing the structure and making full use of surplus space. The straddle-type packer has two specifications of Φ70mm and Φ90mm, with a simple structure and convenient assembly. The test section for in-situ stress measurement of hydraulic fracturing in medium-diameter boreholes is sealed by six components: steel head, upper packer, central pipe, steel head plug, lower packer and central pipe plug.

[0026] 2. The present invention adopts a dual-circuit structure, and provides high-pressure liquid to the fracturing section and the sealing section of the packer through two circuits in the packer. It is mainly used to seal the rock wall of a complete section of rock in the borehole during the hydraulic fracturing test of the rock mass, forming a sealed space, and providing a high-pressure resistant sealing function for subsequent hydraulic fracturing operations.

[0027] 3. By inventing a medium-diameter straddle-type packer, in-situ stress testing for medium-diameter hydraulic fracturing is conducted. The two packer dimensions (Φ70±1mm and Φ90±1mm) meet the requirements for a 40MPa pressure resistance. This allows for on-site hydraulic fracturing testing of medium-diameter boreholes in rock, while also ensuring that the sealing measures meet the 40MPa pressure resistance requirement. The two water inlet holes in the plug are used to supply water to the packer and fracturing section, respectively. The hydraulic fracturing section is tested through the water jet holes in the fracturing tubing between the upper and lower packers. The pressure values ​​of the fracturing section and the packer are simultaneously monitored, facilitating the acquisition of high-quality stress measurement data and enabling in-situ stress measurement for hydraulic fracturing in medium-diameter geological exploration boreholes (Φ70mm and Φ90mm). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the implementation methods of the present application, the following is a brief introduction to the drawings required for use in the implementation methods. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic diagram of the structure of a high-strength straddle-type packer for rock hydraulic fracturing testing provided by an embodiment of the present application;

[0030] Figure 2 A schematic diagram of the cross-section structure of a steel head provided in an embodiment of the present application;

[0031] Figure 3 A schematic diagram of the steel sheet structure provided in an embodiment of the present application;

[0032] Figure 4 A schematic diagram of the cross-sectional structure of the first tube body and the second tube body provided in an embodiment of the present application;

[0033] Figure 5 A schematic diagram of the cross-section structure of the central tube plug provided in an embodiment of the present application;

[0034] Figure 6 This is a schematic diagram of the three-dimensional structure of the anti-blocking fracturing pipe provided in an embodiment of the present application;

[0035] Figure 7 A schematic diagram of a cutaway three-dimensional structure provided in an embodiment of the present application;

[0036] Figure 8 A schematic diagram of the three-dimensional structure of a fracturing flower pipe provided in an embodiment of the present application;

[0037] Figure 9 A schematic diagram of the three-dimensional structure of the anti-backflow assembly provided in an embodiment of the present application;

[0038] Figure 10 A schematic diagram of the three-dimensional structure of the limiting groove provided in an embodiment of the present application;

[0039] Figure 11 A schematic diagram of the three-dimensional structure of the connection between the sealing ring and the compression spring provided in an embodiment of the present application;

[0040] Figure 12 A schematic diagram of the structure of a dual-loop test system composed of a hydraulic fracturing in-situ stress measurement device provided in an embodiment of the present application;

[0041] Figure 13 Schematic diagram of the structure of a single-loop test system composed of a hydraulic fracturing in-situ stress measurement device provided in an embodiment of the present application.

[0042] In the figure: 100, fracturing flower pipe; 200, packer; 201, steel sheet; 210, upper packer; 220, lower packer; 300, steel head; 301, rubber sealing ring A; 302, rubber sealing ring B; 303, rubber sealing ring C; 310, sealing channel; 330, fracturing channel; 400, central pipe; 401, first pipe body; 402, second pipe body; 410, steel head plug; 420, central pipe plug. DETAILED DESCRIPTION

[0043] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; they may refer to direct connection or indirect connection through an intermediate medium; they may refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0045] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0046] See also Figure 1-Figure 5 The present invention provides a high-strength straddle-type packer for rock mass hydraulic fracturing testing, comprising a fracturing flower tube 100, a packer 200, and a central tube 400;

[0047] The end of the fracturing flower pipe 100 is connected to a steel head 300, and the steel head 300 is provided with a sealing channel 310. The steel head 300 is hollow to form a fracturing channel 330; the packer 200 includes an upper packer 210 and a lower packer 220. One end of the upper packer 210 is directly connected to one end of the fracturing flower pipe 100, and one end of the lower packer 220 is threadedly connected to the steel head 300. The upper packer 210 and the lower packer 220 are both expandable packing rubber tubes. The upper packer 210 has a connecting thread at its end, which facilitates connection with the steel head 300. The middle part of the upper packer 210 is an expansion sealing section, in which a steel sheet 201 is embedded. The steel sheet 201 is arranged inside to effectively enhance the strength. During the hydraulic fracturing in-situ stress test, high-pressure fluid enters the expansion sealing section through the push-pull valve connecting pipe and the steel head 300 to expand it and make it fit the hole wall. The upper packer 210 cooperates with the lower packer 220 to achieve the sealing requirement of the test end.

[0048] The central pipe 400 includes a first pipe body 401 and a second pipe body 402. The first pipe body 401 is inserted into the upper packer 210, and the second pipe body 402 is inserted into the lower packer 220. The other end of the first pipe body 401 is threadedly connected to the connecting pipe of the push-pull valve, and the other end of the second pipe body 402 is threadedly connected to the central pipe plug 420. The surface of the second pipe body 402 is provided with a steel head plug 410, and the steel head plug 410 is set in the lower packer 22 0 is close to one end of the central pipe plug 420; the middle part of the central pipe 400 is placed in the inner cavity of the packer 200, forming the expansion sealing section of the packer 200, and the inner cavity of the central pipe 400 serves as an extension of the fracturing channel 330, transporting high-pressure fluid to the fracturing flower pipe 100; the fracturing section water inlet is connected to the sealing channel 310 through an internal pipe, and the sealing channel 310 is threadedly connected to the packer 200 and makes the space between the packer 200 and the central pipe 400 serve as the packer channel. The central rod plug 420 is located at the bottom of the straddle-type packer and is made of 304 stainless steel. Its front end is threaded to connect to the lower packer 220, and its inner hole is threaded to connect to the central pipe 400. Figure 5 As shown, the bottom of the plug is not a through hole, which is resistant to high pressure and leak-proof. In addition, an O-type rubber sealing ring is installed in the groove to achieve the effect of sealing the threaded connection end face.

[0049] In a specific embodiment of the present invention, two steel heads 300 are provided, and the two steel heads 300 are respectively sealed and docked with the two ends of the fracturing flower tube 100. The steel head 300 is provided with a sealing channel 310, and the fracturing flower tube 100 is provided with a sealing through hole. The port of the sealing through hole is docked with the sealing channel 310, and a fracturing channel 330 is provided in the center of the steel head 300.

[0050] In a specific embodiment of the present invention, a sealing groove A is provided at the end of the fracturing flower tube 100, and a protrusion is raised at the end of the steel head 300 to engage with the sealing groove A; a rubber sealing ring C303 is engaged in the sealing groove C provided on the inner wall of the fracturing channel 330.

[0051] In a specific embodiment of the present invention, a rubber sealing ring A301 is clamped in the sealing groove A opened on the outer surface of the convex head, and a rubber sealing ring B302 is clamped in the sealing groove B opened on the inner wall of the convex head. The rubber sealing ring A301 cooperates with the rubber sealing ring B302 to seal the sealing groove A.

[0052] In a specific embodiment of the present invention, the central tube plug 420 is located at the lower end of the steel head plug 410, one end of the central tube plug 420 is directly connected to the steel head plug (410) and a sealing groove is opened and sealed with a sealing ring, and the inner hole of the central tube plug 420 is threadedly connected to the second tube body 402 to block the tail of the fracturing channel 330 here.

[0053] In this embodiment of the present invention, one end of the upper packer 210 has a connecting thread, while both ends of the lower packer 220 have connecting threads. The upper packer 210 and the lower packer 220 have identical structures. To facilitate installation, the threaded connection between the upper packer 210 and the steel head 300 is replaced with a direct fit, i.e., the internal threads of the upper packer 210 are removed. This is the only difference between the upper packer 210 and the lower packer 220.

[0054] In a specific embodiment of the present invention, both ends of the steel head 300 are threaded, connecting to the push-pull valve connecting pipe and the upper packer 210, respectively. The left end of the steel head 300 is connected to the push-pull valve connecting pipe, and four sealing channels 310 are provided, each connected to a corresponding through-hole in the push-pull valve connecting pipe. The fracturing section water inlet hole is connected to the fracturing channel 330 of the fracturing pipe steel head 300 via an internal pipe. The sealing channel 310 is threadedly connected to the packer 200, allowing the space between the packer 200 and the central pipe 400 to serve as the packer channel.

[0055] In a specific embodiment of the present invention, both ends of the central tube 400 are threaded, the outermost end is threadedly connected to the connecting pipe of the push-pull valve and the central tube plug 420, and the inner side is threadedly connected to the fracturing flower pipe, and the upper packer 210 and the lower packer 220 are connected through the fracturing flower pipe to achieve the bridging of the upper and lower packers. Figure 4 The space between the central tube 400 and the packer 200 is the packer passage. An O-ring is installed at the connection groove of the central tube 400 to achieve the function of sealing the threaded connection end face.

[0056] In a specific embodiment of the present invention, the steel head plug 410 is located between the lower packer 220 and the central pipe plug 420. The steel head plug 410 is threadedly connected to the lower packer 220, and is threadedly connected to it and has an O-ring rubber sealing ring at the groove to achieve the effect of sealing the threaded connection end face, thereby blocking the sealing channel 310 here.

[0057] In a specific embodiment of the present invention, rubber sealing rings are respectively provided at the connection grooves of the steel head 300 and the connection grooves of the packer 200, thereby achieving the effect of sealing the threaded connection end faces. During the measurement of in-situ stress caused by hydraulic fracturing, high-pressure liquid enters the fracturing section and the packer sealing section respectively from the internal channels of the steel head 300. One of the high-pressure liquids enters the fracturing section channel of the central pipe 400 through the internal pipes of the fracturing section and the steel head 300. Another high-pressure liquid enters the channel inside the rubber tube of the packer 200 through the internal sealing channel 310 of the steel head 300, causing the rubber tube in the middle of the packer 200 to expand and achieve the effect of sealing the hole wall.

[0058] like Figures 6 to 11 The embodiment of the present invention further provides an integrated device for hydraulic fracturing test, comprising a double-layer filter for hydraulic fracturing test as described above; and an anti-blocking fracturing pipe for hydraulic fracturing test, comprising

[0059] A fracturing flower tube 100 is provided with a central channel 110 therein 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 flower tube 100;

[0060] The connecting steel head 300 is provided with two connecting steel heads 300, and the two connecting steel heads 300 are respectively sealed and docked with the two ends of the fracturing flower tube 100. The connecting steel head 300 is provided with a sealing channel 310, and the fracturing flower tube 100 is provided with a sealing through hole. The port of the sealing through hole is docked with the sealing channel 310. The center of the connecting steel head 300 is provided with a fracturing channel 330, and the fracturing channel 330 is connected with the central channel 110.

[0061] A backflow prevention assembly 500 is also provided. The backflow prevention assembly 500 includes a countersunk screw A510 and a tension spring 530. The countersunk screw A510 is inserted into the countersunk one-way 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 top screw 550 for adjusting the tension.

[0062] In a specific embodiment of the present invention, the countersunk one-way high-pressure fluid output channel 130 is arranged in pairs, including a countersunk hole A and a countersunk hole B. The countersunk hole A and the countersunk hole B are symmetrically arranged on both sides of the central channel 110. The countersunk screw A510 is inserted into the countersunk hole A, and the countersunk screw B570 is inserted into the countersunk hole B. The end of the countersunk screw B570 is provided with an internal threaded hole, and the top screw 550 is connected to the internal threaded hole. The countersunk screw A510 and the countersunk screw B570 are coaxially arranged.

[0063] After long-term use, the sealing contact surface between the countersunk screw A510 and the countersunk one-way high-pressure fluid output channel 130 may wear out, resulting in failure of anti-backflow. For this reason, the following is a specific implementation plan of the anti-blocking fracturing pipe according to the hydraulic fracturing test of this application with reference to the accompanying drawings:

[0064] Specifically, in a specific embodiment of the present invention, a limiting groove 190 is opened on the surface of the fracturing flower tube 100, and 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 is in contact with the conical surface of the countersunk screw A510.

[0065] 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 hole groove, the lower end of the compression spring 193 is fixedly connected to the bottom of the limiting groove 190, the upper end of the compression spring 193 is fixedly connected to the sealing ring 191, and 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 and inserted into the sealing groove D.

[0066] After the inspection is completed, as the high-pressure liquid in the central channel 110 recedes, the countersunk screw A510 is reset under the action of the tension spring 530, and the upper end of the sealing ring 191 contacts the end face of the countersunk screw A510 to achieve a contact seal, effectively preventing the backflow of external liquid. After the upper end of the sealing ring 191 is worn, the elastic action of the compression spring 193 pushes the sealing ring 191 to extend outward to compensate, and always contacts and seals with the conical surface of the countersunk screw A510, so that the sealing contact is always maintained, the equipment service life is delayed, the maintenance cost is reduced, and the backflow caused by airtightness failure due to wear is effectively avoided.

[0067] The working principle of this high-strength straddle-type packer for rock hydraulic fracturing testing is as follows: When the drill pipe is connected to the entire test device and placed at the target test depth, the push-pull valve spool is pulled upward to the top under the device's own weight. A surface high-pressure water pump delivers fracturing fluid into the drill pipe. After being filtered by the filter, the fluid flows along the push-pull valve seating path into the cavity formed by the upper packer 210 and the central pipe 400. From there, it flows along the seating channel 310 of the fracturing pipe into the cavity formed by the lower packer 220 and the central pipe 400. After this process is completed, the upper and lower packers 210 and 220 expand under the action of water pressure and are firmly fixed to the borehole wall, thus sealing and isolating the borehole section between the upper and lower packers 200.

[0068] After the test, the drill pipe is lifted up so that the push-pull valve core is pulled up to the top and is in the seated position. The high-pressure water pump is turned off to connect the ground manifold to the atmosphere. The pressure in the upper and lower packers is released as the high-pressure fluid flows out, and the packer 200 automatically contracts and returns to its original state. Therefore, the pressure relief task is completed.

[0069] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.

Claims

1. A high-strength straddle-type packer for rock mass hydraulic fracturing testing, characterized in that: include A fracturing flower tube (100), wherein the end of the fracturing flower tube (100) is connected to a steel head (300), the steel head (300) is provided with a sealing channel (310), and the steel head (300) is hollow to form a fracturing channel (330); The packer (200) includes an upper packer (210) and a lower packer (220), one end of the upper packer (210) is directly connected to one end of the fracturing flower pipe (100), and one end of the lower packer (220) is threadedly connected to the steel head (300). The upper packer (210) and the lower packer (220) are both expandable packer rubber tubes. The end of the upper packer (210) has a connecting thread for easy connection with the steel head (300). The steel head (300) is connected, and the middle part of the upper packer (210) is an expansion sealing section. The expansion sealing section is embedded with a steel sheet (201), and the steel sheet (201) is arranged inside to effectively enhance the strength. During the hydraulic fracturing in-situ stress test, high-pressure fluid enters the expansion sealing section through the push-pull valve connecting pipe and the steel head (300) to expand it and make it fit with the hole wall. The upper packer (210) cooperates with the lower packer (220) to achieve the sealing requirement of the test end. The central pipe (400) comprises a first pipe body (401) and a second pipe body (402), wherein the first pipe body (401) is inserted into the upper packer (210), and the second pipe body (402) is inserted into the lower packer (220). The other end of the first pipe body (401) is threadedly connected to the connecting pipe of the push-pull valve, and the other end of the second pipe body (402) is threadedly connected to the central pipe plug (420). The surface of the second pipe body (402) is sleeved with a A steel head plug (410) is provided at one end of the lower packer (220) close to the central pipe plug (420); the middle portion of the central pipe (400) is placed in the inner cavity of the packer (200), cooperating to form the expansion sealing section of the packer (200); the inner cavity of the central pipe (400) is connected to the fracturing channel (330) to transport the high-pressure fluid to the fracturing flower pipe (100); the water inlet hole of the fracturing section is connected to the sealing channel (310) through an internal pipeline.

2. A high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 1, characterized in that: Two steel heads (300) are provided, and the two steel heads (300) are sealed and docked with the two ends of the fracturing flower tube (100) respectively. The steel head (300) is provided with a sealing channel (310), and the fracturing flower tube (100) is provided with a sealing through hole. The port of the sealing through hole is docked with the sealing channel (310), and the center of the steel head (300) is provided with a fracturing channel (330).

3. A high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 2, characterized in that: The end of the fracturing flower tube (100) is provided with a sealing groove A, and the end of the steel head (300) is provided with a protrusion that is engaged with the sealing groove A; the sealing groove C provided on the inner wall of the fracturing channel (330) is engaged with a rubber sealing ring C (303).

4. A high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 3, characterized in that: A rubber sealing ring A (301) is clamped in the sealing groove A opened on the outer surface of the convex head, and a rubber sealing ring B (302) is clamped in the sealing groove B opened on the inner wall of the convex head. The rubber sealing ring A (301) cooperates with the rubber sealing ring B (302) to seal the sealing groove A.

5. The high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 3, characterized in that: The central tube plug (420) is located at the lower end of the steel head plug (410), and one end of the central tube plug (420) is directly connected to the steel head plug (410). A sealing groove is provided at the connection between the central tube plug (420) and the steel head plug (410), and the sealing groove is sealed with a sealing ring. The inner hole of the central tube plug (420) is threadedly connected to the second tube body (402).

6. The high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 1, characterized in that: One end of the upper packer (210) is provided with a connecting thread, and both ends of the lower packer (220) are provided with connecting threads; the structures of the upper packer (210) and the lower packer (220) are completely the same.

7. The high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 1, characterized in that: Both ends of the steel head (300) are provided with threaded grooves, which are respectively connected to the push-pull valve connecting pipe and the upper packer (210); the left end of the steel head (300) is connected to the push-pull valve connecting pipe, and four seat sealing channels (310) are provided, and the four seat sealing channels (310) are connected to the corresponding through holes of the push-pull valve connecting pipe.

8. The high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 1, characterized in that: Both ends of the central tube (400) are threaded, the outermost end is threadedly connected to the connecting pipe of the push-pull valve and the central tube plug (420), and the inner side is threadedly connected to the fracturing flower tube (100). The upper packer (210) and the lower packer (220) are connected through the fracturing flower tube to achieve a cross-connection of the upper and lower packers.

9. The high-strength straddle-type packer for rock mass hydraulic fracturing testing according to claim 1, characterized in that: The steel head plug (410) is located between the lower packer (220) and the central pipe plug (420), and the steel head plug (410) is threadedly connected to the lower packer (220).

10. An integrated device for hydraulic fracturing testing, characterized in that: include The double-layer filter for hydraulic fracturing testing according to any one of claims 1 to 9; as well as The anti-blocking fracturing pipe for hydraulic fracturing test is characterized by comprising A fracturing flower tube (100), wherein a central channel (110) is provided in the fracturing flower 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 flower tube (100); A connecting steel head (300), wherein two connecting steel heads (300) are provided, and the two connecting steel heads (300) are sealed and docked with the two ends of the fracturing flower tube (100) respectively, the connecting steel head (300) is provided with a sealing channel (310), the fracturing flower tube (100) is provided with a sealing through hole, the port of the sealing through hole is docked with the sealing channel (310), and the center of the connecting steel head (300) is provided with a fracturing channel (330), and the fracturing channel (330) is connected with the central channel (110).

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