A laboratory staged hydraulic fracturing device and fracturing method

Abstract

The present invention discloses a laboratory segmented hydraulic fracturing device and a fracturing method, the device comprising: N fracturing tubes connected in sequence by threads; a concave groove is provided in the middle of the fracturing tube, and a number of fracturing tube water outlet holes are evenly distributed on the concave groove; N-1 perforated spacers are respectively placed at the connection of the fracturing tubes; N-1 water injection pipes, the right ends of the N-1 water injection pipes extend out of the rightmost fracturing tube, and the left ends of the N-1 water injection pipes are respectively located in the N-1 fracturing tubes on the left; a water injection pump, the water injection pump is arranged on the right side of the water injection pipe. The present invention can realize the segmented hydraulic fracturing test by connecting the water injection pipes at different positions only by the water injection pump; the method provided by the present invention adopts the anchor glue as the binder, so that the bonding between the natural rock block and the segmented hydraulic fracturing device is good, and the phenomenon of liquid cross-linking and liquid leakage generated during the fracturing process can be avoided, thereby improving the success rate of the test. The method provided by the present invention has a simple process, is easy to operate, and is suitable for laboratory test requirements.

Description

Technical Field

[0001] The invention relates to the technical field of staged hydraulic fracturing physical simulation, and in particular to a laboratory staged hydraulic fracturing device and a fracturing method. Background Art

[0002] As a conventional low-permeability oil and gas production enhancement technology, hydraulic fracturing technology was first used on a large scale in the development of low-permeability oil and gas fields. With the in-depth study of hydraulic fracturing technology, repeated fracturing technologies such as staged hydraulic fracturing have been widely used and studied in the fields of petroleum, geothermal mining and coal mining. Among them, the research on the initiation mechanism of staged hydraulic fracturing cracks is mainly focused on the fields of oil production enhancement and ground coalbed methane wells. Through the simulation of horizontal well staged hydraulic fracturing tests under laboratory conditions, the physical process of horizontal well staged hydraulic fracturing under real formation conditions can be well simulated, and the geometric morphology of hydraulic fractures generated during horizontal well staged fracturing can be intuitively displayed.

[0003] The aperture of the sealer used in conventional laboratory staged hydraulic fracturing tests is relatively large, which can easily lead to poor fracturing effect, poor sealing effect and equipment wear. Therefore, in order to ensure the effect of fracturing operation and the stability of equipment, it is urgent to solve the problem of the large aperture of the laboratory staged hydraulic fracturing sealer, improve the fracturing effect of laboratory staged hydraulic fracturing, and further promote the development of fracturing technology. Summary of the invention

[0004] In order to solve the problem of large aperture of laboratory staged hydraulic fracturing sealer, the present invention provides a laboratory staged hydraulic fracturing device and a fracturing method, which not only ensures the effect of fracturing operation, but also ensures the stability of the equipment, and further promotes the development of fracturing technology.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] A laboratory staged hydraulic fracturing device, comprising:

[0007] N fracturing pipes are connected in sequence by threads; a concave groove is provided in the middle of the fracturing pipe, and a number of fracturing pipe water outlet holes are evenly distributed on the concave groove;

[0008] N-1 perforated spacers, respectively placed at the connection of the fracturing pipe;

[0009] N-1 water injection pipes, the right ends of the N-1 water injection pipes extend out of the rightmost fracturing pipe, and the left ends of the N-1 water injection pipes are respectively located in the N-1 fracturing pipes on the left;

[0010] Water injection pump: The water injection pump is arranged on the right side of the water injection pipe.

[0011] Preferably, N=4, i.e., the first fracturing tube, the second fracturing tube, the third fracturing tube, and the fourth fracturing tube are connected in sequence by threads; the first perforated spacer is between the first fracturing tube and the second fracturing tube, the second perforated spacer is between the second fracturing tube and the third fracturing tube, and the third perforated spacer is between the third fracturing tube and the fourth fracturing tube; the first water injection pipe passes through the third perforated spacer, the second perforated spacer, and the first perforated spacer from right to left in sequence and is placed in the first fracturing tube, the second water injection pipe passes through the third perforated spacer and the second perforated spacer from right to left in sequence and is placed in the second fracturing tube, and the third water injection pipe passes through the third perforated spacer and is placed in the third fracturing tube.

[0012] Preferably, the first perforated spacer is provided with a hole for the first water injection pipe to pass through; the second perforated spacer is provided with holes for the first water injection pipe and the second water injection pipe to pass through respectively; the third perforated spacer is provided with holes for the first water injection pipe, the second water injection pipe, and the third water injection pipe to pass through respectively; the water injection pipes are welded to the holes and sealed at the welding positions by anchor glue.

[0013] Preferably, the perforated spacer is placed at the bottom of the internal thread of the fracturing pipe; O-rings are provided on both the left and right sides of the perforated spacer.

[0014] Preferably, a first sealing ring is provided on the outer side of the first fracturing tube between the concave groove and the first perforated spacer; a second sealing ring is provided on the outer side of the second fracturing tube between the concave groove and the second perforated spacer; and a third sealing ring is provided on the outer side of the third fracturing tube between the concave groove and the third perforated spacer.

[0015] The present invention also provides a method for fracturing using a laboratory staged hydraulic fracturing device, comprising the following steps:

[0016] S1: Select natural rock blocks from underground coal mines, process them into standard samples according to the size required for the test, and drill a hole of predetermined diameter and depth in the center of the cross section of the standard sample;

[0017] S2: Assembling a staged hydraulic fracturing device, and after the assembly is completed, lowering the staged hydraulic fracturing device into the standard sample borehole;

[0018] S3: placing the standard sample with the staged hydraulic fracturing device fixed in the true triaxial staged hydraulic fracturing chamber, covering the true triaxial fracturing device with an upper cover, connecting the first water injection pipe to the water injection pump, then applying a set three-way constant confining pressure to the standard sample, turning on the water injection pump, and performing the first fracturing pipe staged hydraulic fracturing test on the sample according to the set water injection flow rate;

[0019] S4: After the hydraulic fracturing of the first fracturing pipe is completed, the second water injection pipe is connected to the water injection pump, and a true triaxial segmented hydraulic fracturing test of the second fracturing pipe is performed on the sample according to the set water injection flow rate;

[0020] S5: After the hydraulic fracturing of the second fracturing pipe is completed, the third water injection pipe is connected to the water injection pump, and a true triaxial segmented hydraulic fracturing test of the third fracturing pipe is performed on the sample according to the set water injection flow rate;

[0021] S6: After the hydraulic fracturing of the third fracturing tube is completed, the true triaxial segmented hydraulic fracturing device releases the three-way confining pressure and takes the standard sample out of the true triaxial segmented hydraulic fracturing chamber.

[0022] Preferably, step S2 specifically includes the following steps:

[0023] S21: fix the O-rings to both sides of the first perforated spacer by using the anchoring glue, place the first perforated spacer at the internal thread of the first fracturing tube, put the first sealing ring on the tail end of the first fracturing tube, seal the first water injection tube and the first perforated spacer with the anchoring glue, then connect the first fracturing tube with the second fracturing tube by the internal and external threads, and lower them into the borehole; fill the foam glue into the gap between the first sealing ring, the tail end of the first fracturing tube and the borehole; after the foam glue is cured, evenly apply the anchoring glue to the gap between the first fracturing tube and the borehole on the right side of the foam glue; wait for the anchoring glue to cure to complete the sealing of the first fracturing tube;

[0024] S22: fix the O-ring to both sides of the second perforated spacer by using anchor glue, place the second perforated spacer at the internal thread of the second fracturing tube, put the second sealing ring on the tail end of the second fracturing tube, seal the first water injection tube, the second water injection tube and the second perforated spacer with anchor glue, then connect the second fracturing tube and the third fracturing tube by internal and external threads, and lower them into the borehole; fill the second sealing ring, the gap between the tail end of the second fracturing tube and the borehole with foam glue; after the foam glue is cured, evenly apply the anchor glue to the gap between the second fracturing tube and the borehole on the right side of the foam glue; wait for the anchor glue to cure to complete the sealing of the second fracturing tube;

[0025] S23: fix the O-ring to both sides of the third perforated spacer by means of anchoring glue, place the third perforated spacer at the inner thread of the third fracturing tube, put the third sealing ring on the tail end of the third fracturing tube, seal the first water injection pipe, the second water injection pipe, the third water injection pipe and the third perforated spacer with anchoring glue, then connect the third fracturing tube and the fourth fracturing tube by means of internal and external threads, and lower them into the borehole; fill the foam glue into the gap between the third sealing ring, the tail end of the third fracturing tube and the borehole; after the foam glue is cured, evenly apply the anchoring glue to the gap between the third fracturing tube and the borehole on the right side of the foam glue; and complete the sealing of the third fracturing tube after the anchoring glue is cured.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention, in conjunction with the use of a large-scale rock triaxial mechanical property testing device, can perform segmented hydraulic fracturing tests on large-scale natural rock blocks under laboratory conditions, and is used to study the mutual influence of different hydraulic fractures in natural rock blocks during expansion. The segmented hydraulic fracturing test can be achieved by simply connecting water injection pipes at different positions through a water injection pump; the method provided by the present invention uses rebar glue as a binder, so that the bonding between the natural rock block and the segmented hydraulic fracturing device is good, which can avoid the phenomenon of cross-liquid and leakage generated during the fracturing process, and improve the success rate of the test. The method provided by the present invention has a simple process, is easy to operate, and is suitable for laboratory test requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the structure of the laboratory staged hydraulic fracturing device of the present invention.

[0030] Figure 2 It is a schematic diagram of the structure of the perforated spacer of the present invention.

[0031] In the figure: 1. standard sample; 21. first fracturing tube; 22. second fracturing tube; 23. third fracturing tube; 24. fourth fracturing tube; 31. first perforated spacer; 32. second perforated spacer; 33. third perforated spacer; 41. first water injection pipe; 42. second water injection pipe; 43. third water injection pipe; 5. water injection pump; 6. concave groove; 7. water outlet hole of fracturing tube; 8. O-ring; 91. first sealing ring; 92. second sealing ring; 93. third sealing ring. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 1 , Figure 2 As shown, a laboratory staged hydraulic fracturing device comprises: a first fracturing pipe 21, a second fracturing pipe 22, a third fracturing pipe 23, and a fourth fracturing pipe 24 connected in sequence by threads; a concave groove 6 is provided in the middle of the fracturing pipe, and a plurality of fracturing pipe water outlet holes 7 are evenly distributed on the concave groove 6;

[0034] A first perforated spacer 31 is provided between the first fracturing tube 21 and the second fracturing tube 22, a second perforated spacer 32 is provided between the second fracturing tube 22 and the third fracturing tube 23, and a third perforated spacer 33 is provided between the third fracturing tube 23 and the fourth fracturing tube 24; the first perforated spacer 31 is provided with a hole for the first water injection pipe 41 to pass through; the second perforated spacer 32 is provided with holes for the first water injection pipe 41 and the second water injection pipe 42 to pass through respectively; the third perforated spacer 33 is provided with holes for the first water injection pipe 41, the second water injection pipe 42 and the third water injection pipe 43 to pass through respectively; the water injection pipes are welded to the holes and sealed at the welding position by embedding glue; the perforated spacer is placed at the bottom of the internal thread of the fracturing tube; O-rings 8 are provided on both sides of the perforated spacer;

[0035] The first water injection pipe 41 passes through the third perforated spacer 33, the second perforated spacer 32, and the first perforated spacer 31 from right to left in sequence and is placed in the first fracturing pipe 21; the second water injection pipe 42 passes through the third perforated spacer 33, the second perforated spacer 32 from right to left in sequence and is placed in the second fracturing pipe 22; the third water injection pipe 43 passes through the third perforated spacer 33 and is placed in the third fracturing pipe 23;

[0036] An injection pump 5 is arranged on the right side of the injection pipe; a first sealing ring 91 is arranged on the outer side of the first fracturing tube 21 between the concave groove 6 and the first perforated spacer 31; a second sealing ring 92 is arranged on the outer side of the second fracturing tube 22 between the concave groove 6 and the second perforated spacer 32; a third sealing ring 93 is arranged on the outer side of the third fracturing tube 23 between the concave groove 6 and the third perforated spacer 33.

[0037] The present invention also provides a method for fracturing using a laboratory staged hydraulic fracturing device, comprising the following steps:

[0038] S1: Select natural rock blocks from underground coal mines, process them into 200mm standard sample 1 according to the required size of the test, and use a water drill to drill a hole with a diameter of 15mm and a depth of 150mm in the center of the cross section of the standard sample 1;

[0039] S2: Assembling a staged hydraulic fracturing device, after the assembly is completed, lowering the staged hydraulic fracturing device into the borehole of the standard sample 1; step S2 specifically includes the following steps:

[0040] S21: fix the O-ring 8 to both sides of the first perforated spacer 31 by using anchoring glue, place the first perforated spacer 31 at the internal thread of the first fracturing tube 21, put the first sealing ring 91 on the tail end of the first fracturing tube 21, seal the first water injection pipe 41 and the first perforated spacer 31 with anchoring glue, then connect the first fracturing tube 21 and the second fracturing tube 22 by internal and external threads, and lower them into the borehole; fill the foam glue into the first sealing ring 91, the gap between the tail end of the first fracturing tube 21 and the borehole; after the foam glue is cured, evenly apply the anchoring glue to the gap between the first fracturing tube 21 and the borehole on the right side of the foam glue; wait for the anchoring glue to cure to complete the sealing of the first fracturing tube 21;

[0041] S22: fix the O-ring 8 to both sides of the second perforated spacer 32 by means of anchoring glue, place the second perforated spacer 32 at the internal thread of the second fracturing tube 22, put the second sealing ring 92 on the tail end of the second fracturing tube 22, seal the first water injection pipe 41, the second water injection pipe 42 and the second perforated spacer 32 with anchoring glue, then connect the second fracturing tube 22 and the third fracturing tube 23 by means of internal and external threads, and lower them into the borehole; fill the second sealing ring 92, the gap between the tail end of the second fracturing tube 22 and the borehole with foam glue; after the foam glue is cured, evenly apply the anchoring glue to the gap between the second fracturing tube 22 and the borehole on the right side of the foam glue; wait for the anchoring glue to cure to complete the sealing of the second fracturing tube 22;

[0042] S23: fix the O-ring 8 to both sides of the third perforated spacer 33 by means of anchoring glue, place the third perforated spacer 33 at the inner thread of the third fracturing tube 23, put the third sealing ring 93 on the tail end of the third fracturing tube 23, seal the first water injection pipe 41, the second water injection pipe 42, the third water injection pipe 43 and the third perforated spacer 33 with anchoring glue, then connect the third fracturing tube 23 and the fourth fracturing tube 24 by means of inner and outer threads, and lower them into the borehole; fill the foam glue into the gap between the third sealing ring 93, the tail end of the third fracturing tube 23 and the borehole; after the foam glue is cured, evenly apply the anchoring glue to the gap between the third fracturing tube 23 and the borehole on the right side of the foam glue; wait for the anchoring glue to cure to complete the sealing of the third fracturing tube 23;

[0043] The foam glue has low compressive resistance and its main function is to fill the gap between the fracturing tube and the drill hole for pre-sealing to prevent the direct application of the anchor glue from blocking the fracturing tube water outlet hole 7 on the previous fracturing tube through the sealing ring and the fracturing tube before the anchor glue solidifies. After the anchor glue solidifies, the segmented hydraulic fracturing effect is poor. Evenly filling the foam glue can solve this problem. After the anchor glue solidifies, the compressive strength is high, which prevents the fracturing fluid from overflowing through the sealing ring and the fracturing tube, thereby causing inaccurate segmented fracturing points and reducing the fracturing effect.

[0044] S3: Place the standard sample 1 with the staged hydraulic fracturing device fixed in the true triaxial staged hydraulic fracturing chamber, cover the true triaxial fracturing device with the upper cover, connect the first water injection pipe 41 to the water injection pump 5, then apply the set three-way constant confining pressure to the standard sample 1, start the water injection pump 5, and perform the first fracturing pipe 21 staged hydraulic fracturing test on the sample at a water injection flow rate of 5 mL / min;

[0045] S4: After the hydraulic fracturing of the first fracturing pipe 21 is completed, the second water injection pipe 42 is connected to the water injection pump 5, and the water injection flow rate is 5 mL / min to perform a true triaxial segmented hydraulic fracturing test on the second fracturing pipe 22 on the sample;

[0046] S5: After waiting for the hydraulic fracturing of the second fracturing pipe 22 to be completed, the third water injection pipe 43 is connected to the water injection pump 5, and the water injection flow rate is 5 mL / min to perform a true triaxial segmented hydraulic fracturing test on the third fracturing pipe 23 on the sample;

[0047] S6: After the hydraulic fracturing of the third fracturing pipe 23 is completed, the true triaxial segmented hydraulic fracturing device releases the three-way confining pressure and takes the standard sample 1 out of the true triaxial segmented hydraulic fracturing chamber.

Claims

1. A laboratory staged hydraulic fracturing method, characterized in that: The steps include: S1: Select natural rock blocks from underground coal mines, process them into standard samples (1) according to the size required for the test, and drill a hole of a predetermined diameter and depth in the center of the cross section of the standard sample (1); S2: Assembling a staged hydraulic fracturing device. After the assembly is completed, the staged hydraulic fracturing device is lowered into the borehole of the standard sample (1); the staged hydraulic fracturing device comprises: A first fracturing pipe (21), a second fracturing pipe (22), a third fracturing pipe (23), and a fourth fracturing pipe (24) are connected in sequence by threads; a concave groove (6) is provided in the middle of the fracturing pipes, and a plurality of fracturing pipe water outlet holes (7) are evenly distributed on the concave groove (6); a first perforated spacer (31) is provided between the first fracturing pipe (21) and the second fracturing pipe (22); a second perforated spacer (32) is provided between the second fracturing pipe (22) and the third fracturing pipe (23); and a second perforated spacer (32) is provided between the third fracturing pipe (23) and the fourth fracturing pipe (24). The third perforated spacer (33) is provided with a hole for the first water injection pipe (41) to pass through; the second perforated spacer (32) is provided with holes for the first water injection pipe (41) and the second water injection pipe (42) to pass through respectively; the third perforated spacer (33) is provided with holes for the first water injection pipe (41), the second water injection pipe (42), and the third water injection pipe (43) to pass through respectively; O-rings (8) are provided on both sides of the perforated spacer; and a sealing ring is provided on the outer side of the fracturing pipe between the concave groove (6) and the perforated spacer; The first water injection pipe (41) passes through the third perforated spacer (33), the second perforated spacer (32), and the first perforated spacer (31) in sequence from right to left and is placed in the first fracturing pipe (21); the second water injection pipe (42) passes through the third perforated spacer (33), the second perforated spacer (32) in sequence from right to left and is placed in the second fracturing pipe (22); the third water injection pipe (43) passes through the third perforated spacer (33) and is placed in the third fracturing pipe (23); the water injection pipe is welded to the hole and sealed at the welding position by using a reinforcing bar glue; A water injection pump (5), the water injection pump (5) being arranged on the right side of the water injection pipe; S3: placing the standard sample (1) with the staged hydraulic fracturing device fixed in the true triaxial staged hydraulic fracturing chamber, covering the true triaxial fracturing device with an upper cover, connecting the first water injection pipe (41) to the water injection pump (5), then applying a set three-way constant confining pressure to the standard sample (1), starting the water injection pump (5), and performing a true triaxial staged hydraulic fracturing test on the sample using the first fracturing pipe (21) according to a set water injection flow rate; S4: After waiting for the hydraulic fracturing of the first fracturing pipe (21) to be completed, the second water injection pipe (42) is connected to the water injection pump (5), and a true triaxial segmented hydraulic fracturing test of the second fracturing pipe (22) is performed on the sample according to a set water injection flow rate; S5: After waiting for the hydraulic fracturing of the second fracturing pipe (22) to be completed, the third water injection pipe (43) is connected to the water injection pump (5), and a true triaxial segmented hydraulic fracturing test of the third fracturing pipe (23) is performed on the sample according to a set water injection flow rate; S6: After the hydraulic fracturing of the third fracturing tube (23) is completed, the three-way confining pressure of the true triaxial segmented hydraulic fracturing device is released, and the standard sample (1) is taken out from the true triaxial segmented hydraulic fracturing chamber.

2. The method of laboratory staged hydraulic fracturing according to claim 1, characterized in that: The perforated spacer is placed at the bottom of the internal thread of the fracturing pipe.

3. The method of laboratory staged hydraulic fracturing according to claim 1, characterized in that: A first sealing ring (91) is provided on the outer side of the first fracturing tube (21) between the concave groove (6) and the first perforated spacer (31); a second sealing ring (92) is provided on the outer side of the second fracturing tube (22) between the concave groove (6) and the second perforated spacer (32); and a third sealing ring (93) is provided on the outer side of the third fracturing tube (23) between the concave groove (6) and the third perforated spacer (33).

4. The method of laboratory staged hydraulic fracturing according to claim 3, characterized in that: Step S2 specifically includes the following steps: S21: fix the O-ring (8) to both sides of the first perforated spacer (31) by using a reinforcing glue, place the first perforated spacer (31) at the internal thread of the first fracturing tube (21), put the first sealing ring (91) on the tail end of the first fracturing tube (21), seal the first water injection tube (41) and the first perforated spacer (31) with reinforcing glue, then connect the first fracturing tube (21) and the second fracturing tube (22) by internal and external threads and lower them into the borehole; fill the foam glue into the gap between the first sealing ring (91), the tail end of the first fracturing tube (21) and the borehole; after the foam glue is cured, evenly apply the reinforcing glue to the gap between the first fracturing tube (21) and the borehole on the right side of the foam glue; and complete the sealing of the first fracturing tube (21) after the reinforcing glue is cured; S22: fix the O-ring (8) to both sides of the second perforated spacer (32) by means of anchoring glue, place the second perforated spacer (32) at the internal thread of the second fracturing tube (22), put the second sealing ring (92) on the tail end of the second fracturing tube (22), seal the first water injection tube (41), the second water injection tube (42) and the second perforated spacer (32) with anchoring glue, then connect the second fracturing tube (22) and the third fracturing tube (23) by means of internal and external threads and lower them into the borehole; fill the second sealing ring (92), the gap between the tail end of the second fracturing tube (22) and the borehole with foam glue; after the foam glue is cured, evenly apply the anchoring glue to the gap between the second fracturing tube (22) and the borehole on the right side of the foam glue; and complete the sealing of the second fracturing tube (22) after the anchoring glue is cured; S23: fix the O-ring (8) to both sides of the third perforated spacer (33) by means of anchoring glue, place the third perforated spacer (33) at the inner thread of the third fracturing tube (23), put the third sealing ring (93) on the tail end of the third fracturing tube (23), seal the first water injection tube (41), the second water injection tube (42), the third water injection tube (43) and the third perforated spacer (33) with anchoring glue, then connect the third fracturing tube (23) and the fourth fracturing tube (24) by means of internal and external threads and lower them into the borehole; fill the foam glue into the gap between the third sealing ring (93), the tail end of the third fracturing tube (23) and the borehole; after the foam glue is cured, evenly apply the anchoring glue to the gap between the third fracturing tube (23) and the borehole on the right side of the foam glue; and complete the sealing of the third fracturing tube (23) after the anchoring glue is cured.

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