CN108999586A - Minor diameter rock mass hydrofracturing tests straddle packer - Google Patents

Abstract

The invention discloses a bridge-type packer for hydraulic fracturing testing of small-diameter rock mass, which includes a double-circuit installation rod connector, an upper packer, a connector with a water spray hole, and a lower packer and a lower plug; the double-circuit installation rod connector, the upper packer, the connector with water spray holes, the lower packer and the lower plug are closely connected in sequence. The beneficial effects of the present invention are: the in-situ stress measurement scheme of hydraulic fracturing in small-diameter boreholes is realized. The bridge packer has two specifications of Φ30mm and Φ39mm. It has simple structure and convenient assembly. The five components of the installation rod connector, the upper packer, the connector with water spray holes, the lower packer and the lower plug realize the sealing of the test section and the in-situ stress measurement of hydraulic fracturing in small-diameter boreholes. Jetting of high-pressure liquids.

Description

Small-diameter rock mass hydraulic fracturing test bridge packer

technical field

The invention relates to a small-diameter rock mass testing tool, in particular to a bridge-type packer for small-diameter rock mass hydraulic fracturing testing.

Background technique

Hubbert and Willis proposed in 1957 that the fractures produced by wellbore fluid fracturing are closely related to the stress state existing in the rock mass, and pointed out that the rock mass pressure is not in the state of hydrostatic pressure. Kehle (1964) made a simple analysis of the stress distribution around the wellbore in the experimental section isolated by the packer for the first time, and pointed out that the effect of the packer formed a shear stress zone around the hole wall. Fairhurst (1964) was the first scientist to propose the use of hydraulic fracturing technology to measure in-situ stress, and pointed out many advantages of hydraulic fracturing technology. Haimson and Fairhurst (1967) pointed out that the fractures on the borehole wall are related to the following three factors: ① crustal stress, ② differential stress between hydraulic fracturing liquid pressure and pore water pressure; ③ radial flow rate of rock mass penetration , these theoretical analyzes have laid the theoretical foundation for classical hydraulic fracturing testing techniques. In his doctoral dissertation, Haimson (1968) comprehensively analyzed and perfected the hydraulic fracturing in-situ stress testing technology from both experimental and theoretical aspects. The above important works have laid a theoretical and experimental foundation for the application of hydraulic fracturing in situ stress testing technology to engineering practice. The real engineering practice of stress measurement was carried out in an underground granite body in Minnesota by the research group led by Von Schonfeldt and Fairhurst (1970); subsequently, similar stress measurement and research work was carried out in the Rangely oil field (Haimson , 1973; Raleigh et al., 1976). Since then, hydraulic fracturing stress measurement has officially entered the field of engineering practice. In 1987 and 2003, the International Society of Rock Mechanics recommended the in-situ stress measurement method of hydraulic fracturing as a main stress estimation method, and also established the importance of in-situ stress measurement technology of hydraulic fracturing as a stress testing method. status.

China's in-situ stress measurement work is slightly later than that of foreign countries. In the late 1950s, Professor Li Siguang and Professor Chen Zongji respectively directed the Institute of Geomechanics and the Three Gorges Rock Foundation Special Research Group to start. In October 1980, the research team led by Professor Li Fangquan successfully carried out the hydraulic fracturing method in-situ stress measurement for the first time in Yixian County, Hebei (Li Fangquan, 1980), and then the Institute of Crustal Stress of China Earthquake Administration successfully developed a portable hydraulic fracturing method. Crack measurement equipment (Li Fangquan, 1981; Ding Jianmin, 1990; An Qimei, 1996; Guo Qiliang, 1999). Hydraulic fracturing testing technology has been widely applied and promoted in various industries in China. So far, the main hydraulic fracturing test methods used in China follow the methods recommended by the International Society of Rock Mechanics.

The equipment for in-situ stress measurement of hydraulic fracturing is mainly divided into five categories: (1) Heavy-duty cable-type hydraulic fracturing in-situ stress measurement equipment, represented by 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 Australia’s CSIRO organization; The new hydraulic fracturing test equipment combined with geophysical logging equipment; (4) The BABHY test equipment manufactured by Professor Ito of Tohoku University in Japan; Fracture in situ stress measurement equipment. Among all these equipment, the smallest equipment diameter is the portable hydraulic fracturing in situ stress measurement equipment manufactured by CSIRO, with a diameter of Ф36mm, followed by the BABHY test equipment manufactured by Professor Ito. The test drilling diameter is Ф48mm.

The measurement system widely used in China consists of six parts, pressure fluid control system, high pressure water pump, power system, data recording system, bridge packer and high pressure fluid delivery system. This measurement system is further divided into two categories, one is for shallow holes of 100m, and the drill pipe and high-pressure hose can be used to supply water to the packer and the fracturing section respectively to achieve fracturing. Another kind of equipment is aimed at the measurement of the deep hole above 100m. A switching valve is used to supply the pressure liquid to the fracturing stage and the packer respectively. The diagram of the test system is shown in Figure 1 and Figure 2. Among them: 40, 30: drill stand, 41: high-pressure hose, 42, 32: drill pipe connection test section, 43, 33: adapter, 44, 34: test section, 45, 35: packer, 46, 36: Pressure Sensor.

According to the previous analysis, there is no hydraulic fracturing ground stress testing system with a diameter less than 36mm in the world at present. However, the small-diameter hydraulic fracturing in-situ stress test system has the characteristics of portable equipment and low requirements for test pressurization equipment. It can be pressurized by a manual pressurization system with high output pressure and low flow rate or a two-phase electric high-pressure oil pump. At the same time, small-diameter testing equipment has low requirements for complete rock mass. For large-caliber drilling, according to the International Society of Rock Mechanics, the length of the test section should be 6 to 7 times the diameter of the drilling hole, so for the domestic conventional 76mm Or for a 94mm geological exploration drill hole, plus a packer length of about 1.0m, the length of the complete rock mass for the drill hole is at least 245.6cm~256.4cm, but for a drill hole with a diameter of 32mm, only The length of the complete rock mass, which is about 99.2cm long, is only less than 40% of the original. Under the same working conditions, the amount of test data can be more than doubled. At the same time, the drilling cost will decrease as the borehole diameter becomes smaller, which greatly reduces the test cost of in-situ stress, and the test time for small-diameter drilling will also be shortened, thereby reducing the test cost. Greatly reduced. Therefore, the research and development of small-diameter in-situ stress testing equipment has important social and economic significance for promoting the in-situ stress measurement of hydraulic fracturing and promoting the upgrading and innovation of original technologies.

For the small-diameter hydraulic fracturing test system, due to the large diameter of drill pipes, high-pressure rubber hoses and other equipment used in conventional hydraulic fracturing in-situ stress tests, it is impossible to use the original technical approach to install high-pressure liquid and test equipment in the Book a spot. The present invention adopts the existing technical route, adopts a double-circuit structure, provides high-pressure liquid for the fracturing section and the sealing section of the packer respectively through two circuits in the packer, and designs and manufactures the bridge of the small-diameter hydraulic fracturing test device type packer.

Contents of the invention

The present invention is a small-diameter rock mass hydraulic fracturing test bridge packer designed to solve the above-mentioned technical problems.

The technical solution adopted by the present invention to solve its technical problems is:

A small-diameter rock hydraulic fracturing test bridge packer, including a double-circuit installation rod connector, an upper packer, a connector with a water spray hole, a lower packer and a lower plug head; the double-circuit installation rod connection head, upper packer, connector with water spray holes, lower packer and lower plug are closely connected in sequence.

In the small-diameter rock mass hydraulic fracturing test bridge packer, the material of the connecting head of the double-circuit installation rod is 304 stainless steel, and there are threads at both ends, which are respectively connected to the double-circuit installation rod and the upper packer. The water inlet hole of the packer connecting head of the installation rod is connected to the channel of the rubber barrel of the packer, and the water inlet hole of the fracturing section of the connecting head of the double circuit installation rod is connected to the channel of the fracturing section of the packer; there is a circle at each end of the connecting head of the double circuit installation rod Groove, O-shaped rubber sealing rings are respectively worn at the connection groove of the double circuit installation rod connection head and the connection groove with the packer to realize the sealing of the threaded connection end face.

The diameter of the small-diameter rock mass hydraulic fracturing test bridge packer, the water inlet hole of the packer at the joint of the double-circuit installation rod and the water inlet hole of the fracturing section are all Φ6mm.

The small-diameter rock mass hydraulic fracturing test bridge packer, the upper packer and the lower packer are of the same model, and their internal structures are the same, both are expansion packer rubber tubes, expansion packers There are two types of rubber cartridges: Φ31mm and Φ39mm; the pressure resistance of these two packers can reach 40MPa, and the temperature resistance can reach 130℃.

In the small-diameter rock mass hydraulic fracturing test bridge packer, the upper and lower packers both include an upper connecting section, an expansion sealing section, and a lower connecting section; both ends of the upper and lower packers have connecting There are steel sheets inside the middle expansion sealing section to enhance its strength.

The small-diameter rock mass hydraulic fracturing test bridge-type packer, the material of the connector with the water spray hole is 304 stainless steel, and the two ends of the connector are threaded, and the upper and lower two packers are connected; There are two channels in the device, which are the packer channel and the fracturing section channel; a Φ6mm stainless steel pipe with a wall thickness of 1.5mm passes through the middle of the fracturing section channel, and the steel pipe is firmly welded to the bottom of the lower plug. together; there are three water spray holes connected to the channel of the fracturing section on the connector, the packer channel connects the rubber barrels of the upper packer and the lower packer, and the connector is at the connecting groove of the upper and lower packer Wear an O-shaped rubber sealing ring to realize the sealing of the threaded connection end face.

The small-diameter rock mass hydraulic fracturing test bridge-type packer, the material of the lower plug is 304 stainless steel, the front end is threaded to connect with the lower packer, and the rear end is rolled on the surface to increase its friction. A 304 stainless steel pipe of Φ6mm and wall thickness of 1.5mm is welded in the middle of the plug. The stainless steel pipe is a fracturing channel with a length of 1.18m. The bottom of the lower plug is firmly welded with the stainless steel pipe, which is resistant to high pressure and does not Air leakage; and O-shaped rubber sealing ring is worn at the groove to realize the sealing of the threaded connection end face.

The present invention is mainly used in the hydraulic fracturing test of small-diameter boreholes of rock mass. Its function is to seal a section of the rock wall of a complete rock mass in the borehole to form a sealed space for subsequent hydraulic fracturing operations. Provides the function of high pressure resistant sealing. By inventing the bridge packer, its diameter is Ф30±1mm, Φ39±1mm, and the pressure resistance reaches 40MPa, which can realize the on-site hydraulic fracturing test of medium and small diameter drilling holes in rock mass.

The small-diameter hydraulic fracturing in-situ stress test is carried out by means of the small-diameter bridged packer of the present invention, which meets the requirements of the two packers with external dimensions Φ30±1mm, Φ39±1mm and pressure resistance of 40MPa, and sealing measures at the same time It also meets the requirement of pressure resistance of 40MPa. Water is supplied to the packer and the fracturing section through the two water inlet holes of the double-circuit installation rod joint, and the hydraulic fracturing test of the sealing section is carried out through the water injection holes of the connector between the upper and lower two packers, and Simultaneously monitoring the pressure values of the fracturing section and the packer is conducive to obtaining high-quality stress measurement data and realizing in-situ stress measurement of hydraulic fracturing in Φ38mm and Φ44mm small-diameter geological exploration boreholes.

The beneficial effect of the present invention is that: the hydraulic fracturing in-situ stress measurement scheme in the small-diameter borehole is realized. The bridge packer has two specifications of Φ30mm and Φ39mm. It has simple structure and convenient assembly. The five components of the installation rod connector, the upper packer, the connector with water spray holes, the lower packer and the lower plug realize the sealing of the test section and the in-situ stress measurement of hydraulic fracturing in small-diameter boreholes. Jetting of high-pressure liquids.

Description of drawings

Fig. 1 is a schematic diagram of a bridged packer of an in-situ stress measurement device for hydraulic fracturing in an existing dual-loop testing system.

Fig. 2 is a schematic diagram of a bridging packer of an in-situ stress measurement device for hydraulic fracturing in an existing single-circuit testing system.

Fig. 3 is a schematic diagram of the overall internal structure of the bridge packer of the present invention.

Fig. 4 is a mechanical structure diagram of the double-circuit mounting rod connection head of the present invention.

Fig. 5 is a mechanical structure diagram of the packer of the present invention.

Fig. 6 is a mechanical structure diagram of a connector with a water spray hole according to the present invention.

Fig. 7 is a mechanical structure diagram of the lower plug of the present invention.

Detailed ways

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

As shown in Figure 3-7, the present invention is a small-diameter rock mass hydraulic fracturing test bridge packer, including a double-circuit installation rod connector 1, an upper packer 2, and a water spray hole 3 Connector 4, a lower packer 7 and a lower plug 8; double circuit installation rod connector 1, upper packer 2, connector 4 with water spray hole 3, lower packer 7 and lower The plugs 8 are closely connected successively.

In the small-diameter rock mass hydraulic fracturing test bridge packer, the material of the double-circuit installation rod connector 1 is 304 stainless steel, and there are threads at both ends, which are respectively connected to the double-circuit installation rod and the upper packer. The packer inlet hole 5 of the connection head 1 of the circuit installation rod is connected to the channel 12 of the rubber barrel of the packer, and the water inlet hole 6 of the fracturing section of the connection head 1 of the double circuit installation rod is connected to the channel 13 of the fracturing section of the packer; the double circuit installation rod There is a circle of grooves 11 at both ends of the connector 1, and O-shaped rubber sealing rings are respectively worn at the connection groove 11 of the double-circuit installation rod connector and the groove 11 connected with the packer to realize the sealing of the threaded connection end face.

The diameter of the small-diameter rock mass hydraulic fracturing test bridge packer, the packer water inlet 5 of the double-circuit installation rod connector 1 and the water inlet 6 of the fracturing section are both Φ6mm in diameter.

The bridge packer for the hydraulic fracturing test of the small-diameter rock mass, the upper packer 2 and the lower packer 7 are of the same model, and their internal structures are the same. There are two types of packer rubber cylinders, Φ31mm and Φ39mm; the pressure resistance of the two packers can reach 40MPa, and the temperature resistance can reach 130℃.

During the measurement of the in-situ stress of hydraulic fracturing, as shown in Fig. 4, the high-pressure liquid enters the water inlet hole of the fracturing stage and the water inlet hole of the packer respectively from the two channels inside the double-circuit installation rod, and the high-pressure liquid passes through the The water inlet hole of the fracture section and the internal pipe of the joint head enter the channel of the fracturing section between the packers, and another high-pressure liquid enters the channel inside the rubber cylinder of the packer through the water inlet hole of the packer and the internal pipe of the joint head, so that the sealing The rubber tube in the middle of the separator expands to seal the hole wall. In addition, O-shaped rubber sealing rings are respectively worn at the connection groove of the double-circuit installation rod connection head and the connection groove with the packer to achieve the sealing effect of the threaded connection end face.

In the small-diameter rock mass hydraulic fracturing test span packer, the upper and lower packers 2 and 7 both include an upper connecting section 14, an expansion sealing section 15 and a lower connecting section 16; the upper and lower packers Both ends of 2 and 7 are provided with connecting threads 17, and there is a steel sheet 18 inside the middle expansion sealing section 15 to enhance its strength. As shown in Figure 5, during the in-situ stress measurement process of hydraulic fracturing, the high-pressure liquid enters the expansion sealing section through the internal pipeline to expand it, and makes it fit the hole wall, and reaches the testing section through the upper and lower packers. Sealing requirements.

The small-diameter rock mass hydraulic fracturing test bridge packer, the connector 4 with the water spray hole 3 is made of 304 stainless steel, and the two ends of the connector are threaded to connect the upper and lower packers , as shown in Figure 6; there are two channels in the connector 4, which are respectively the packer channel 21 and the fracturing section channel 22; wherein the intermediate fracturing section channel 22 passes through a stainless steel pipe with a diameter of 6mm and a wall thickness of 1.5mm , the steel pipe is firmly welded to the bottom of the lower plug 8; there are three water spray holes 3 connected to the channel 22 of the fracturing section on the connector 4, which are used to spray high-pressure liquid outward during the hydraulic fracturing process . The packer channel 21 connects the rubber cylinders of the upper packer and the lower packer, and is used for the expansion of the rubber cylinder by the high-pressure liquid during hydraulic fracturing, so as to realize the sealing of the fracturing section of the borehole wall. The connector 4 wears an O-shaped rubber sealing ring at the connection groove 20 of the upper and lower packers to realize the sealing of the threaded connection end face.

The small-diameter rock mass hydraulic fracturing test bridge packer, the material of the lower plug 8 is 304 stainless steel, the front end is threaded to connect with the lower packer, and the rear end is rolled on the surface to increase its friction. The middle part of the lower plug 8 is welded with a 304 stainless steel pipe with a diameter of 6 mm and a wall thickness of 1.5 mm. The stainless steel pipe is the fracturing channel 24, and the length of the stainless steel pipe is 1.18 m. High pressure and airtight; and 23 O-shaped rubber sealing rings are worn at the groove to realize the sealing of the threaded connection end face.

This set of equipment has been tested in the simulated environment of the in-situ stress test in the laboratory, and the application effect is good. The detailed description of the experimental process is as follows:

(1) Use steel pipes with inner diameters of Ф34mm and Ф44mm to simulate small-diameter drilling on site, and connect high-pressure oil pumps, high-pressure fluid control systems, double-circuit installation rods, and small-diameter bridge packers.

(2) Open the outlet valve of the oil pump, close the fracturing section ball valve and pressure relief ball valve, pressurize the packer, and check the seat seal function. The packer monitoring pressure gauge shows that the packer has a pressure resistance of 40MPa and the seat seal ability is good.

(3) Open the outlet valve of the oil pump, close the needle valve and pressure relief ball valve of the packer, pressurize the fracturing section, and check the fracturing function. 50MPa, high pressure fluid fracturing output capacity is good.

(4) During the test, the sealing performance of each connecting piece is good, there is no leaking, leaking, and pressure maintenance stability is good.

(5) Open the oil return valve of the oil pump, close the oil outlet valve, open the needle valve of the packer, the ball valve of the fracturing section, and the pressure relief ball valve to complete the pressure relief operation.

The present invention is not limited to the above-mentioned best implementation mode, and any other product identical or similar to the present invention obtained by anyone under the inspiration of the present invention falls within the protection scope of the present invention.

Claims (7)

1. A bridge-type packer for hydraulic fracturing testing of small-diameter rock mass, including a double-circuit installation rod connector (1), an upper packer (2), and a connector with a water spray hole (3) device (4), a lower packer (7) and a lower plug (8); it is characterized in that: a double circuit installation rod connector (1), an upper packer (2), with water spray holes (3 ), the lower packer (7) and the lower plug (8) are tightly connected in sequence. 2. The small-diameter rock mass hydraulic fracturing test bridge packer according to claim 1, characterized in that: the material of the double-circuit installation rod connector (1) is 304 stainless steel, and there are threads at its two ends, Connect the dual-circuit installation rod and the upper packer respectively, the packer inlet hole (5) of the dual-circuit installation rod connector (1) is connected to the packer rubber barrel channel (12), and the dual-circuit installation rod connector (1 The water inlet hole (6) of the fracturing section of the ) is connected to the channel (13) of the fracturing section of the packer; there is a circle of grooves (11) at both ends of the double-circuit installation rod connector (1), and there is a circle of grooves (11) at both ends of the double-circuit installation rod connector. O-shaped rubber sealing rings are respectively worn at the groove (11) and the groove (11) connecting with the packer to realize the sealing of the end face of the threaded connection. 3. The bridge-type packer for small-diameter rock mass hydraulic fracturing test according to claim 2, characterized in that: the packer inlet hole (5) of the double-circuit installation rod connector (1) and the pressure Split segment water inlet (6), its diameter is Φ 6mm. 4. The bridge-type packer for small-diameter rock mass hydraulic fracturing test according to claim 1, characterized in that: the upper packer (2) and the lower packer (7) are of the same type, and the inner The structure is the same as the expandable packer rubber cartridge, and the expandable packer rubber cartridge has two types of Φ31mm and Φ39mm; the pressure resistance of the two packers can reach 40MPa, and the temperature resistance can reach 130℃. 5. The bridge-type packer for hydraulic fracturing test of small-diameter rock mass according to claims 1 and 4, characterized in that: the upper and lower packers (2, 7) both include an upper connecting section (14) , the expansion sealing section (15) and the lower connection section (16); both ends of the upper and lower packers (2, 7) are provided with connecting threads (17), and the middle expansion sealing section (15) has internal threads to enhance its strength Steel sheet (18). 6. The bridge-type packer for hydraulic fracturing test of small-diameter rock mass according to claim 1, characterized in that: the material of the connector (4) with the water spray hole (3) is 304 stainless steel, and the two connectors There are threads at the end to connect the upper and lower packers; there are two channels in the connector (4), which are the packer channel (21) and the fracturing section channel (22); the middle fracturing section The channel (22) passes through a Φ6mm stainless steel pipe with a wall thickness of 1.5mm, and the steel pipe is firmly welded to the bottom of the lower plug (8); there are three channels connected to the fracturing section ( 22), the water spray hole (3) of the packer channel (21) connects the rubber barrels of the upper packer and the lower packer, and the connector (4) is at the connecting groove (20) of the upper packer and the lower packer Wear an O-shaped rubber sealing ring to realize the sealing of the threaded connection end face. 7. The small-diameter rock mass hydraulic fracturing test bridge packer according to claims 1 and 6, characterized in that: the material of the lower plug (8) is 304 stainless steel, and the front end has threads and the lower packing The rear end is rolled cross-shaped on the surface to increase its friction. A 304 stainless steel tube with a diameter of 6mm and a wall thickness of 1.5mm is welded in the middle of the lower plug (8). The stainless steel tube is the fracturing channel (24). The length of the stainless steel tube is It is 1.18m, and the bottom of the lower plug is firmly welded with the stainless steel pipe, which is high pressure resistant and airtight; and an O-shaped rubber sealing ring is worn at the groove (23) to realize the sealing of the threaded connection end face.