A drag-fracturing adjustable span combined tool for old well

Abstract

The present application relates to a kind of old well drag fracturing span adjustable combination tool, to solve the technical problem that old well fracturing construction process cannot meet the sealing and clamping moment adjustable, also cannot realize the upper end and lower end double clamping and double sealing operation of fracturing working section.The tool includes sequentially connected bidirectional hydraulic slip, hydraulic internal pressure booster packer with expansion joint, track type bottom seal packer and centralizer positioner;Hydraulic internal pressure booster packer with expansion joint includes hydraulic packer assembly and expansion assembly consisting of cylinder outer tube and expansion piston tube;Hydraulic packer assembly includes second center tube and outer tube, second piston is arranged between cylinder outer tube and expansion piston tube, and second piston is slidingly fitted with the inner cavity of cylinder outer tube;The lower end of cylinder outer tube is provided with guide sleeve, and second piston is abutted with guide sleeve when sliding downward to maximum distance;The lower end of cylinder outer tube is provided with multiple pressure relief slits extending along axial direction and penetrating through cylinder outer tube.

Description

TECHNICAL FIELD

[0001] The present application relates to oil well drag fracturing device, particularly to an adjustable combination tool for drag fracturing of old well. BACKGROUND

[0002] In the process of fracturing operation of old well in oil field, in order to achieve the requirement of multi-layer drag fracturing operation of one trip string, the tool string must meet the upper and lower pack-off and adjustable pack-off distance, but the existing oil well drag fracturing device cannot achieve it. SUMMARY

[0003] The present application aims to solve the technical problems that the pack-off distance cannot be adjusted and the upper end and lower end of the fracturing section cannot be double packed and sealed in the process of fracturing operation of old well, and proposes an adjustable combination tool for drag fracturing of old well.

[0004] The technical scheme of the present application is as follows:

[0005] An adjustable combination tool for drag fracturing of old well, characterized in that it comprises a bidirectional hydraulic slip, a hydraulic internal booster packer with an extension joint, a track type bottom packer and a centralizer positioner, which are connected in sequence from top to bottom.

[0006] The bidirectional hydraulic slip is used for upper connection with the perforation section.

[0007] The hydraulic internal booster packer with an extension joint comprises a hydraulic pack-off assembly and an extension assembly connected to the hydraulic pack-off assembly.

[0008] The hydraulic pack-off assembly comprises a second central pipe and an outer cylinder, and is used for sealing the upper part of the oil well fracturing section.

[0009] The extension assembly comprises a cylinder outer pipe and an extension piston pipe arranged in the cylinder outer pipe.

[0010] The cylinder outer pipe of the extension assembly is fixed to the lower end of the outer cylinder.

[0011] The top end of the extension piston pipe is fixed with a second piston, which is in sliding fit with the side wall of the inner cavity of the cylinder outer pipe.

[0012] The inner side of the lower end of the cylinder outer pipe is provided with a guide sleeve, the extension piston pipe is in sliding fit with the inner side wall of the guide sleeve, and the second piston can abut against the guide sleeve when the extension piston pipe slides to the maximum distance.

[0013] The lower end of the cylinder outer pipe is provided with a plurality of pressure relief slits extending in the axial direction, and the pressure relief slits are located at the position of the cylinder outer pipe close to the guide sleeve, and the pressure relief slits extend through the cylinder outer pipe in the radial direction.

[0014] The second central pipe is communicated with the telescopic piston pipe;

[0015] The lower end of the telescopic piston pipe has a thread for connecting with a joint segment of a track-type bottom packer;

[0016] The bidirectional hydraulic slip has a first central pipe; the upper end of a second central pipe of the hydraulic packer assembly is connected with the first central pipe;

[0017] The centralizing positioner is used for positioning the tool string during lowering and ensuring that the tool string is in the center of the casing.

[0018] Further, the width of the pressure relief slit is less than the particle diameter of the sand or ceramic proppant used in the well fracturing.

[0019] The sand or ceramic proppant contained in the collected oil is prevented from entering between the telescopic piston pipe and the outer pipe of the cylinder barrel, thereby affecting the normal use of the telescopic piston pipe.

[0020] Further, the hydraulic packer assembly further comprises a first sealing rubber sleeve arranged outside the second central pipe and a first piston;

[0021] The first sealing rubber sleeve is arranged between the second upper joint and the outer barrel, the upper end of the first piston protrudes out of the outer barrel and abuts against the first sealing rubber sleeve, and the lower end of the first piston protrudes into the outer barrel and between the second central pipe.

[0022] Further, the hydraulic inner-boosting packer with telescopic joint further comprises a throttling assembly arranged between the hydraulic packer assembly and the telescopic assembly, the throttling assembly comprises a throttling sleeve, a magnetic seat arranged inside the lower part of the throttling sleeve and magnetically attracted to the second piston, and a throttling nozzle arranged inside the magnetic seat, the throttling nozzle has a throttling hole, the radial cross-sectional diameter of the throttling hole is less than the radial cross-sectional diameter of the second central pipe, and the throttling hole is communicated with the second central pipe and the telescopic piston pipe;

[0023] The throttling sleeve is arranged between the outer barrel and the outer pipe of the cylinder barrel; the upper segment of the throttling sleeve protrudes into the outer barrel and the second central pipe, the lower segment protrudes into the outer pipe of the cylinder barrel and the magnetic seat, and the middle segment protrudes outward and abuts against the outer barrel and the outer pipe of the cylinder barrel;

[0024] The throttling sleeve has a fourth flow channel; the fourth flow channel is arranged in the upper segment of the throttling sleeve, extends axially along the throttling sleeve and penetrates upward through the throttling sleeve; the gap between the upper end of the first piston and the lower end of the throttling sleeve is communicated with the fourth flow channel;

[0025] A throttling sleeve is arranged at the lower part of the second central pipe, a plurality of third flow channels are arranged on the sidewall of the throttling sleeve and penetrate the throttling sleeve in the radial direction; a second annular groove is arranged between the throttling sleeve and the middle segment of the throttling sleeve, and the third flow channels and the fourth flow channel are communicated with the second annular groove.

[0026] Further, the bidirectional hydraulic slip comprises a first upper joint, a first central pipe, a plurality of bidirectional slip assemblies arranged outside the first central pipe, hydraulic drive assemblies symmetrically arranged on the upper end and lower end of the bidirectional slip assemblies, and a first lower joint;

[0027] The plurality of bidirectional slip assemblies are uniformly distributed along the central axis of the first central pipe;

[0028] The hydraulic drive assembly comprises a compression sleeve, a first connecting sleeve, a support ring, a second connecting sleeve, and a tapered sleeve;

[0029] One end of the compression sleeve and the first connecting sleeve of one of the hydraulic drive assemblies is connected to the first upper joint; one end of the compression sleeve and the first connecting sleeve of the other hydraulic drive assembly is connected to the first lower joint; the other end of the first connecting sleeve has a gap with the tapered sleeve;

[0030] The other end of the tapered sleeve is provided with an outer tapered surface matched with the bidirectional slip assembly; the first connecting sleeve and the second connecting sleeve are axially connected in series;

[0031] The middle part of the first connecting sleeve is sealingly connected to the support ring, and the sidewall of the support ring is provided with a first flow channel extending along the axial direction of the support ring and penetrating through the sidewall of the support ring in the radial direction;

[0032] The inner side of the first connecting sleeve has a ring cavity and a second flow channel penetrating through the first connecting sleeve in the axial direction and towards the bidirectional slip assembly, and the first flow channel, the ring cavity, and the second flow channel constitute a first hydraulic channel, which is used to drive the tapered sleeve to compress the bidirectional slip assembly to realize sealing under the action of high-pressure liquid.

[0033] Further, the track-type bottom packer comprises a joint section and a central rod connected below the joint section, which are connected in series from top to bottom; and further comprises a main sealing rubber sleeve, a tapered body, a slip assembly, and a centralizer guide body assembly, which are connected in series from top to bottom outside the central rod;

[0034] The joint section comprises an upper connection section for connecting with the oil pipe, a lower connection section for connecting with the central rod, and a pressure-guiding sandblasting assembly arranged between the upper connection section and the lower connection section;

[0035] The pressure-guiding sandblasting assembly comprises a plurality of guide sandblasting openings uniformly distributed in the circumferential direction;

[0036] The centralizer guide body assembly comprises a centralizer body, the centralizer body is provided with a mounting groove, a friction body for frictionally matching with the casing is arranged in the mounting groove, and the lower end of the centralizer guide body assembly is provided with an inwardly protruding guide pin;

[0037] The outer surface of the lower section of the central rod is provided with a guide rail groove in the axial direction; the guide rail groove comprises a long guide rail groove and a short guide rail groove extending in the axial direction, and a reversing guide rail groove connecting the lower end of the long guide rail groove and the lower end of the short guide rail groove; in the circumferential direction, the long guide rail groove and the short guide rail groove are arranged at intervals.

[0038] The guide pin cooperates with the guide rail groove.

[0039] Further, the slip assembly comprises a plurality of slip components, the slip component comprising a second slip seat, a plurality of second slip teeth and a plurality of second slip tooth retracting springs, the upper end of the second slip tooth extending out of the upper end of the second slip seat, and the lower end of the second slip tooth being connected in the second slip seat through the second slip tooth retracting spring;

[0040] The second slip seat is connected with the central body.

[0041] Further, the conical body comprises a conical cap surrounding the central rod and a conical body connected below the conical cap; the conical cap, the conical body and the central rod form a first installation cavity;

[0042] The central rod is provided with an annular protrusion, which is arranged in the first installation cavity;

[0043] When the guide pin cooperates with the top end of the short guide rail groove, the annular protrusion has a gap with the lower inner surface of the first installation cavity;

[0044] Or, when the guide pin cooperates with the top end of the long guide rail groove, the annular protrusion pushes down the conical body to make the conical surface of the conical body inserted between the slip tooth and the central rod.

[0045] Further, the central body comprises a guide central body and a plurality of positioning components connected with the guide central body;

[0046] The guide central body comprises a guide body, a connecting groove arranged on the guide body and a plurality of lower limit grooves arranged in the connecting groove;

[0047] The positioning component comprises a positioning body, a limiting groove arranged on the positioning body and an upper limiting groove arranged correspondingly with the lower limiting groove;

[0048] The cavity formed by the lower limiting groove and the upper limiting groove is provided with a compression spring, and an elastic member is arranged between the limiting groove and the connecting groove, for supporting the positioning body and making the positioning body float in the radial direction.

[0049] Further, the positioning body comprises a positioning protrusion, and a first guide section and a second guide section arranged on both sides of the positioning protrusion, and the end surface of the positioning protrusion is a circular arc surface.

[0050] The beneficial effects of the present application are:

[0051] 1. The hydraulic inner-pressurized packer with telescopic section in the application can adjust the sealing distance between the hydraulic inner-pressurized packer with telescopic section and the track type bottom seal packer through the telescopic assembly, and has higher practicability compared with the existing fixed length pipeline connection mode, and is not only suitable for new well perforation fracturing construction, but also suitable for old well fracturing stimulation construction of existing multi-layer perforation section and different perforation length.

[0052] 2. The telescopic assembly can effectively reduce the overall length of the whole tool string and ensure smooth downhole operation.

[0053] 3. The track type bottom seal packer is provided with a pressure guide sand blasting assembly at the upper end joint section, and has the corresponding sand blasting function without additional pressure guide sand blaster, so that the length of the oil well fracturing tool string can be shortened and the use is facilitated. In addition, the main sealing rubber sleeve, the cone, the slip body assembly and the centralizer guide body assembly are sequentially sleeved outside the central rod, and the long guide rail groove and the short guide rail groove are alternately and spacedly arranged on the lower end surface of the central rod, and the sealing and clamping between the bottom seal packer and the oil pipe are realized through the cooperation of the guide pin and the guide rail groove.

[0054] 4. The bidirectional hydraulic slip can expand outward through two groups of hydraulic drive assemblies, so that reliable clamping in two directions can be realized, and damage of the slip caused by uneven stress on both sides of the bidirectional slip can be prevented.

[0055] 5. The centralizer positioner combines the conventional guide centralizer and the conventional positioner into one, forms a composite centralizer positioner with comprehensive functions of guiding, rigid centralizing, elastic centralizing and positioning sensing, has compact structure, complete functions and good centralizing effect, and reduces the length of the whole tool string, which is more conducive to the downhole operation and the lifting of the tool string. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 It is a structural schematic diagram of an embodiment of the application;

[0057] Figure 2 It is a structural schematic diagram of a bidirectional hydraulic slip in an embodiment of the application;

[0058] Figure 3 It is a structural schematic diagram of the hydraulic inner-pressurized packer with telescopic section in a retracted state in an embodiment of the application;

[0059] Figure 4 It is Figure 3 a local enlarged view of A in FIG. 8;

[0060] Figure 5 It is Figure 3 a local enlarged view of B in FIG. 8;

[0061] Figure 6Structure schematic view of the hydraulic inner-boosted packer with telescopic joint in the extended state in the embodiment of the present application;

[0062] Figure 7 Structure schematic view of the track type bottom sealing packer in the embodiment of the present application (unlocked state);

[0063] Figure 8 Structure schematic view of the track type bottom sealing packer in the embodiment of the present application (locked state); Figure 7 Local enlarged view of the position I in the structure schematic view;

[0064] Figure 9 Local enlarged view of the position II in the structure schematic view; Figure 7 Local enlarged view of the position III in the structure schematic view;

[0065] Figure 10 Local enlarged view of the position III in the structure schematic view; Figure 7 Local enlarged view of the position III in the structure schematic view;

[0066] Figure 11 Structure schematic view of the composite track type bottom sealing packer in the embodiment of the present application (locked state);

[0067] Figure 12 Structure schematic view of the righting positioner in the embodiment of the present application;

[0068] Figure 13 Front view of the righting assembly of the righting positioner in the embodiment of the present application;

[0069] Figure 14 Front view of the positioning assembly of the righting positioner in the embodiment of the present application.

[0070] The reference signs are as follows: 1 - bidirectional hydraulic slip, 11 - first upper joint, 12 - hydraulic drive assembly, 121 - compression sleeve, 122 - first connecting sleeve, 123 - support ring, 124 - second connecting sleeve, 125 - taper sleeve, 13 - first central pipe, 14 - bidirectional slip assembly, 141 - first slip seat, 142 - spring, 143 - first slip tooth, 144 - bow spring, 15 - first lower joint;

[0071] 2 - hydraulic inner-boosted packer with telescopic joint, 21 - second upper joint, 22 - first sealing rubber sleeve, 221 - spring steel wire, 222 - first annular groove, 23 - first piston, 24 - outer cylinder, 25 - second central pipe, 26 - magnetic seat, 27 - throttling nozzle, 28 - second piston, 29 - telescopic piston pipe, 210 - cylinder outer pipe, 2101 - pressure relief cutting slot, 211 - guide sleeve, 212 - second hydraulic channel, 213 - throttling sleeve, 241 - upper section of outer cylinder, 242 - middle section of outer cylinder, 243 - lower section of outer cylinder, 2121 - fourth flow channel, 2122 - second annular groove, 2123 - third flow channel;

[0072] 3 - rail type bottom seal packer, 31 - joint segment, 32 - central rod, 33 - main sealing sleeve, 35 - cone cap, 36 - cone, 37 - slip assembly, 38 - centralizer assembly, 310 - hard alloy layer, 311 - tubing box, 312 - guide sand outlet, 314 - first installation cavity, 315 - shear pin, 321 - blind hole, 322 - long guide rail groove, 323 - short guide rail groove, 324 - reversing guide rail groove, 325 - buffer groove, 326 - annular protrusion, 331 - circumferential groove, 332 - circular spring, 371 - second slip seat, 372 - second slip tooth, 373 - second slip tooth retraction spring, 381 - centralizer main body, 382 - support elastic body, 383 - friction body, 384 - ring sleeve, 385 - guide ring, 386 - guide pin, 3811 - installation groove, 3851 - through hole;

[0073] 4 - centralizer positioner, 41 - centralizer body, 42 - pressing plate, 43 - positioning body, 44 - leaf spring, 45 - compression spring, 46 - bolt, 411 - fourth upper joint, 412 - intermediate body, 413 - centralizer, 414 - guide head, 4121 - connecting groove, 4122 - lower limit groove, 4131 - centralizing protrusion, 431 - limiting groove, 432 - upper limit groove, 433 - positioning protrusion, 434 - installation edge, 435 - first guide segment, 436 - first guide segment. DETAILED DESCRIPTION

[0074] In the embodiment, the front end in the falling direction of the oil well is lower, and the rear end is upper.

[0075] REFERENCE Figure 1 The embodiment of the present application provides an old well drag fracturing slip adjustable combined tool, which comprises, from top to bottom along the axial direction, a bidirectional hydraulic slip 1, a hydraulic internal booster packer 2 with an expansion joint, a rail type bottom seal packer 3 and a centralizer positioner 4. The bidirectional hydraulic slip 1 is used for clamping the upper part of the casing, the rail type bottom seal packer 3 is used for clamping the lower part of the casing and sealing the fracturing construction section and performing perforation fracturing, and the centralizer positioner 4 is used for improving the positioning accuracy of the tool string and ensuring that the tool string is in the center of the casing when the tool string is lowered.

[0076] REFERENCE Figure 2The bidirectional hydraulic slip 1 comprises a first upper joint 11, a first lower joint 15, a first central pipe 13, a bidirectional slip assembly 14 arranged outside the first central pipe of the bidirectional hydraulic slip, and two hydraulic drive assemblies 12. The first central pipe 13 is sleeved with the bidirectional slip assembly 14 and the hydraulic drive assemblies 12 arranged symmetrically on the upper end and the lower end of the bidirectional slip assembly. The upper end of the hydraulic drive assembly 12 on the upper end of the bidirectional slip assembly 14 is connected with the first upper joint 11, and the lower end of the other hydraulic drive assembly 12 is connected with the first lower joint 15. The two hydraulic drive assemblies 12 can simultaneously drive the bidirectional slip assembly 14 to expand outward, so that reliable clamping of the slip can be realized, and damage of the slip caused by uneven force on both sides of the slip can be prevented.

[0077] The hydraulic drive assembly 12 comprises a compression sleeve 121, a first connecting sleeve 122, a support ring 123, a taper sleeve 125, and a second connecting sleeve 124. Taking the hydraulic drive assembly 12 on the upper end of the bidirectional slip assembly 14 as an example, the first connecting sleeve 122 is connected with the first upper joint 11 at the upper end. The first connecting sleeve 122 and the second connecting sleeve 124 are connected in series along the axial direction. The lower part of the first connecting sleeve 122 and the upper part of the taper sleeve 125 are sleeved in the second connecting sleeve 124. There is a gap between the lower end of the first connecting sleeve 122 and the upper end of the taper sleeve 125. The lower end of the taper sleeve 125 is provided with an outer taper surface. Both ends of the bidirectional slip assembly 14 are provided with an inner taper surface matched with the outer taper surface. The taper sleeve 125 can slide along the axial direction between the second connecting sleeve 124 and the first central pipe 13.

[0078] The first connecting sleeve 122 is provided with a ring cavity and a second flow channel extending along the axial direction and towards the bidirectional slip assembly 14 in the ring cavity and penetrating through the lower end of the first connecting sleeve 122. The support ring 123 is sealingly connected in the first connecting sleeve 122. The support ring 123 is compressed in the first connecting sleeve 122 by the compression sleeve 121. The compression sleeve 121 is threadedly connected in the first connecting sleeve 122. The side wall of the support ring 123 is provided with a first flow channel. The first flow channel connects the inner cavity of the support ring 123 and the ring cavity of the first connecting sleeve 122. The first flow channel, the ring cavity, and the second flow channel form a first hydraulic channel. The first hydraulic channel communicates with the gap between the first connecting sleeve 122 and the taper sleeve 125. The first hydraulic channel is used to drive the taper sleeve 125 to compress the bidirectional slip assembly 14 to realize sealing under the action of high-pressure liquid. Specifically, the first flow channel is a slit provided on the side wall of the support ring 123. The slit extends along the axial direction of the support ring 123 and penetrates through the side wall of the support ring 123 along the radial direction.

[0079] The bidirectional slip assembly 14 comprises a first slip seat 141 and a plurality of first slip teeth 143, the first slip seat 141 is located between the two second connecting sleeves 124, the first slip seat 141 is provided with a first mounting groove, and the first slip teeth 143 are located in the first mounting groove; the outer side of the first slip seat 141 is provided with an inner conical surface at both ends, and the two inner conical surfaces are in abutment with the outer conical surfaces of the two taper sleeves 125.

[0080] The elastic member is arranged between the first slip teeth 143 and the first slip seat 141, and the elastic member can provide a contraction force for the first slip teeth 143. Specifically, the elastic member is a bow spring 144, the first slip teeth 143 are provided with a second mounting groove, the two ends of the bow spring 144 are in abutment with the inner walls of the first slip seat 141, the middle part of the bow spring 144 is in abutment with the groove bottom of the second mounting groove, and the elastic action of the bow spring 144 can make the first slip teeth 143 disengage from the casing.

[0081] The reset member is arranged between the first slip seat 141 and the taper sleeves 125 at both ends, and the reset member can provide a force for the taper sleeves 125 to move away from the first slip seat 141. Specifically, the reset member is a spring 142, the first slip seat 141 is provided with a spring seat, the taper sleeve 125 is provided with an axially extending spring accommodating groove, one end of the spring 142 is in abutment with the spring seat, and the other end of the spring 142 extends into the spring accommodating groove. The bow spring 144 and the spring 142 cooperate to make the first slip teeth 143 disengage from the casing and realize the reset of the first slip teeth 143.

[0082] Referring to Figures 3 to 6 , the hydraulic internal pressure boosting packer with telescopic joints comprises a hydraulic sealing assembly, a throttling assembly and a telescopic assembly.

[0083] The hydraulic sealing assembly is used for realizing the casing annulus sealing of the upper part of the oil well fracturing section, and comprises a second upper joint 21, a first sealing rubber sleeve 22, a first piston 23, a second central pipe 25, an outer cylinder 24 and a throttling sleeve 213; the upper end of the second upper joint 21 is machined with a tubing box, the lower end of the second upper joint 21 is connected with the second central pipe 25, and the outer part of the second central pipe 25 is sequentially sleeved with the first sealing rubber sleeve 22, the first piston 23 and the outer cylinder 24 from top to bottom; the first sealing rubber sleeve 22 is arranged between the second upper joint 21 and the outer cylinder 24, the upper end of the first piston 23 extends out of the outer cylinder 24 and abuts against the first sealing rubber sleeve 22, and the lower end of the first piston 23 extends into the outer cylinder 24 and the second central pipe 25;

[0084] The throttling sleeve 213 is arranged between the outer cylinder 24 and the cylinder outer pipe 210, the upper section of the throttling sleeve 213 extends into the outer cylinder 24 and the second central pipe 25, and the middle section of the throttling sleeve 213 abuts against the outer cylinder 24 and the cylinder outer pipe 210;

[0085] The throttle sleeve 213 has a fourth flow channel 2121; the fourth flow channel 2121 is arranged in the upper section of the throttle sleeve 213 extending into the outer cylinder 24 and the second central pipe 25, and extends axially along the throttle sleeve 213 and penetrates the throttle sleeve 213 axially; the gap between the upper end of the throttle sleeve and the lower end of the first piston communicates with the fourth flow channel.

[0086] The third flow channel 2123 is arranged in the lower section of the second central pipe 25, and penetrates the second central pipe 25 radially, extends axially along the second central pipe 25, and is uniformly distributed circumferentially; the second annular groove 2122 is arranged between the second central pipe 25 and the throttle sleeve 213, and communicates with the third flow channel 2123. It can be understood that a throttle sleeve can be embedded in the lower section of the second central pipe 25, and a plurality of third flow channels 2123 can be arranged on the throttle sleeve, penetrating the throttle sleeve radially, and a second annular groove 2122 is arranged between the throttle sleeve and the throttle sleeve 213; the throttle sleeve can facilitate replacement of the throttle sleeve without the need to replace and maintain the entire second central pipe 25 in the case of damage to the third flow channel 2123 caused by the action of high-pressure liquid during use.

[0087] The fourth flow channel 2121, the second annular groove 2122, and the plurality of third flow channels 2123 constitute a second hydraulic passage 212 in communication, and the high-pressure liquid in the second central pipe 25 applies a thrust force to the first piston 23 through the second hydraulic passage 212, drives the first sealing rubber sleeve 22 to compress and cause the first sealing rubber sleeve 22 to change elastically and protrude outward to achieve sealing with the casing.

[0088] The first sealing rubber sleeve 22 is provided with spring wires 221 at both ends, which can protect the deformation of the first sealing rubber sleeve 22 at both ends in the compressed state, and avoid the failure of the first sealing rubber sleeve 22 due to the rupture of both ends; the outer cylindrical surface and the inner wall surface of the first sealing rubber sleeve 22 are provided with a plurality of first annular grooves 222.

[0089] The throttle assembly includes a magnetic seat 26 and a throttle nozzle 27; the magnetic seat 26 is connected to the inner side of the lower section of the throttle sleeve 213, and the throttle nozzle 27 is arranged close to the inner side surface of the magnetic seat 26; the throttle nozzle 27 has a throttle hole, the area of the radial section of the throttle hole is smaller than the area of the radial section of the second central pipe 25, and a pressure difference is formed at the upper and lower ends of the throttle hole; in order to prevent the throttle nozzle 27 from being eroded and damaged, the throttle nozzle 27 is made of an erosion-resistant material.

[0090] The telescopic assembly comprises a cylinder outer tube 210, a telescopic piston tube 29, a second piston 28 and a guide sleeve 211, the upper end of the cylinder outer tube 210 is connected to the outside of the lower section of the throttle sleeve 213 and abuts against the middle section of the throttle sleeve 213, the inner side of the lower end is connected to the guide sleeve 211, the cylinder outer tube 210 is provided with the telescopic piston tube 29, the upper end of the telescopic piston tube 29 is fixedly connected to the second piston 28 through screw threads, and the second piston 28 is in sliding fit with the inner cavity of the cylinder outer tube 210.

[0091] The telescopic piston tube 29 is connected to the second piston 28 in sliding fit in the cylinder outer tube 210, the outer diameter of the second piston 28 is matched with the inner diameter of the cylinder outer tube 210, the telescopic piston tube 29 is in sealing fit with the guide sleeve 211 on the inner side of the cylinder outer tube 210, the second piston 28 can slide axially along the cylinder outer tube 210 when the telescopic piston tube 29 moves up and down, and the lower end of the telescopic piston tube 29 extends out of the cylinder outer tube 210 in the extended state during operation, and the lower end of the telescopic piston tube 29 is machined with a pipe pin.

[0092] The outer cylinder 24 comprises an outer cylinder upper section 241, an outer cylinder middle section 242 and an outer cylinder lower section 243, and the inner diameter of the outer cylinder upper section 241 is greater than that of the outer cylinder middle section 242; the first piston 23 is located in the outer cylinder upper section 241, and the upper end of the first piston 23 abuts against the sealing rubber tube 222 after extending out of the upper end of the outer cylinder upper section 241; the outer cylinder middle section 242 has a gap with the first piston 23, and the gap is communicated with the hydraulic channel; the inner side of the outer cylinder lower section 243 is connected to the throttle sleeve 213.

[0093] The lower end of the cylinder outer tube 210 is connected to the telescopic piston tube 29 in sealing fit through the guide sleeve 211, a plurality of pressure relief slits 2101 extending in the axial direction and penetrating in the radial direction are arranged on the side wall of the cylinder outer tube 210, the pressure relief slits 2101 are arranged at the position close to the guide sleeve 211 of the cylinder outer tube 210 and are uniformly distributed along the circumferential direction of the cylinder outer tube 210.

[0094] Referring to Figures 7-11 , the track type bottom sealing packer 3 comprises, from top to bottom, a joint section 31 with a pressure guide sand spraying assembly, a main sealing rubber sleeve 33, a center rod 32, a conical body, a slip assembly 37 and a centralizing guide body assembly 38.

[0095] The upper part of the connector section 31 with the pressure-guided sandblasting assembly is connected to the oil pipe via an oil pipe nut 311, and the lower part is connected to the center rod 32. Several pressure-guided sandblasting assemblies are located in the middle section. Each pressure-guided sandblasting assembly has multiple circumferentially distributed guide sand outlets 312. A high-wear-resistant alloy material is sprayed and welded around the guide sand outlets 312 to form a hard alloy layer 310, thereby improving the lifespan of the sandblasting nozzles and meeting the requirements of multi-layer, high-volume fracturing. In this embodiment, there are four guide sand outlets 312. In other embodiments, the number of guide sand outlets 312 can be three or five. The number of guide sand outlets 312 can be set according to actual working conditions.

[0096] The main sealing sleeve 33 is a single composite sleeve. The outer circumference and inner hole of the main sealing sleeve 33 each have three circumferentially arranged circumferential grooves 331, which are conducive to the compression deformation of the main sealing sleeve 33. Circular springs 332 are bonded to both ends of the outer ring of the main sealing sleeve 33. Their function is to protect the deformation of both ends of the main sealing sleeve 33 after compression and to prevent the main sealing sleeve 33 from breaking and failing at both ends.

[0097] The slip assembly 37 includes a second slip seat 371, a plurality of second slip teeth 372, and a plurality of second slip tooth retraction springs 373. The upper end of the second slip tooth 372 extends out of the upper end of the second slip seat 371, and the lower end of the slip tooth 372 is elastically connected to the second slip seat 371.

[0098] The centering guide assembly 38 includes a centering body 381, a friction element 383, a supporting elastic body 382, ​​a ring 384, a guide ring 385 disposed within the ring 384, and a guide pin 386. The guide ring 385 has a through hole 3851, through which the guide pin 386 extends into a specific guide groove of the center rod 32. The outer cylindrical surface of the centering body 381 has multiple mounting grooves 3811 for mounting the friction element 383. The supporting elastic body 382 provides a force to the friction element 383 in a direction away from the bottom of the mounting grooves 3811. The upper end of the centering body 381 extends into the second slip seat 371 and is connected to the lower end of the second slip tooth 372 by screws and a slip tooth retraction spring 373. Specifically, refer to... Figure 9 The supporting elastic body 382 is a bow spring 144, the middle part of the bow spring 144 abuts against the friction body 383, and the two ends of the bow spring 144 abut against the bottom of the mounting groove 3811.

[0099] The upper part of the center rod 32 is threaded to the joint section 31 with the pressure-guided sandblasting assembly, and the lower part is connected to the centering positioner 4. The lower part of the outer surface of the center rod 32 has a specific guide groove, namely multiple long track grooves 322 or multiple short track grooves 323, which satisfies the axial movement and guiding function of the centering guide assembly 38. The upper part of the center rod 32 is sprayed with hard alloy and has a buffer pit to avoid the fracturing fluid in the oil pipe from affecting its erosion.

[0100] The upper end surface of the central rod 32 is provided with a buffer groove 325, and the central rod 32 is provided with a downward opening blind hole 321. The outer cylindrical surface of the central rod 32 is provided with a plurality of long track grooves 322 and a plurality of short track grooves 323 which are arranged in an axial direction and are spaced apart. The lower ends of the long track grooves 322 and the short track grooves 323 are connected to each other through a reversing guide rail groove 324, and the upper end of the long track groove 322 is higher than the upper end of the short track groove 323. The guide pin 386 can slide along the long track groove 322 or the short track groove 323.

[0101] The conical body includes a conical cap 35 and a conical body 36. The conical body 36 is connected to the central rod 32, and the direction towards the slip assembly 37 is the smaller end of the radial cross-sectional area of the conical body, which satisfies the outward expansion support function of the second slip tooth 372 in the slip assembly 37. The inner wall of the conical cap 35, the inner wall of the conical body 36 and the outer wall of the central rod 32 jointly form a first mounting cavity 314. The central rod 32 is provided with an annular protrusion 326, and the conical cap 35 is connected with the annular protrusion 326 through a shear pin 315. After the shear pin 315 is sheared, the annular protrusion 326 can slide in the first mounting cavity 314.

[0102] Referring to Figures 12 to 14 , the centralizer 4 includes a centralizer body 41, a pressing plate 42, a plurality of positioning bodies 43 and a plurality of elastic members. The centralizer body 41 is composed of a guide head 414, a centralizing body 413, an intermediate body 412 and a fourth upper joint 411 from bottom to top as a whole. The pressing plate 42 is fixed on the centralizer body 41 by bolts 46; the positioning body 43 is embedded in the pressing plate 42 and can float in the radial direction.

[0103] The elastic member is installed inside the positioning body 43 to support the positioning body 43, so as to ensure that the positioning body 43 is always in the maximum allowable size. When the combined tool string moves in the casing, due to the gap at the casing connection, when the positioning body 43 passes through the gap, the sharp part outside the positioning body 43 will extend into the casing gap, causing the change of the pipe string lifting force (friction force), so that the tool depth into the well can be determined by the surface depth measuring device.

[0104] Referring to Figure 13 and Figure 14 , the guide head 414 is a hemisphere. The centralizing body 413 is provided with at least three centralizing protrusions 4131 which are uniformly distributed in the circumferential direction, and the surface of the centralizing protrusion 4131 is a circular arc surface. The intermediate body 412 is a cylindrical body, and the cylindrical surface of the cylindrical body is provided with at least three connection grooves 4121 which are uniformly distributed in the circumferential direction.

[0105] Referring to Figures 13 to 14In the embodiment, the number of the connecting grooves 4121, the positioning bodies 43 and the elastic members is three, and the number of the righting protrusions 4131 is six. The three positioning bodies 43 are connected in the corresponding connecting grooves 4121 respectively, and each of the positioning bodies 43 is provided with a positioning protrusion 433. The surface of the positioning protrusion 433 is a plane or a circular arc surface, and the length of the positioning protrusion 433 is less than the width of the gap between the adjacent casings. The positioning protrusion 433 is made of hard alloy material. The two sides of the positioning protrusion 433 are provided with a first guide segment 435 and a first guide segment 436, and the first guide segment 435 is close to the righting body 413. It can be understood that the number of the connecting grooves 4121, the positioning bodies 43 and the elastic members can be four or set according to actual needs.

[0106] The elastic member is arranged between the groove bottom of the connecting groove 4121 and the positioning body 43. The elastic member can provide a force along the radial direction of the cylinder away from the cylinder for the positioning body 43, so as to support the positioning body 43 and make the positioning body 43 float along the radial direction. Specifically, the elastic member is a leaf spring 44, and the positioning body 43 is provided with a limiting groove 431. The length of the limiting groove 431 is matched with the length of the compressed leaf spring 44. In the embodiment, two compression springs 45 are further arranged in the connecting groove 4121. The positioning body 43 is provided with an upper limiting recess 432. The bottom surface of the first positioning groove is provided with a lower limiting recess 4122 corresponding to the position of the upper limiting recess 432. The first end of the compression spring 45 is located in the upper limiting recess 432, and the second end of the compression spring 45 is located in the lower limiting recess 4122.

[0107] The positioning body 43 is provided with two installation edges 434. The two installation edges 434 are located on the two sides of the length direction of the positioning body 43 respectively, and the surface of the installation edge 434 is lower than the surface of the positioning body 43. The two ends of the connecting groove 4121 are provided with a pressing plate 42. The pressing plate 42 includes two limiting parts and two connecting parts. The connecting part is located outside the limiting part, and the connecting part is connected to the righting body 41 through a bolt 46. The limiting part corresponds to the two installation edges 434 of the positioning body 43, and limits the positioning body 43. When the surface of the pressing plate 42 is flush with the surface of the positioning body 43 at the preset position, the pressing plate 42 can prevent the positioning body 43 from continuing to move away from the righting body 41 after reaching the preset position.

[0108] The working principle of the old well drag fracturing clamping and distance adjustable combined tool in the embodiment is as follows:

[0109] The tool string enters the well, and the righting guide body assembly 38 of the track-type bottom packer 3 contains a friction body 383. When the combined tool string enters the well, the telescopic piston pipe 29 is compressed and retracted into the cylinder outer pipe 210, which reduces the length of the entire tool string and facilitates the entry into the well. According to the righting positioner 4, the combined tool string is determined to be placed at the designated position, and the length of the perforation section is determined in combination with the formation data, so as to accurately ensure that the lower sealing and clamping point of the combined tool string is located at the lower part of the perforation section, and the upper sealing point of the telescopic piston pipe 29 after extension is located at the upper part of the perforation section, so as to ensure that the upper and lower sealing points completely cover the perforation section.

[0110] The righting body 41 in the righting positioner 4 is used for righting of the combined tool string. After the positioning body 43 contacts the gap at the casing connection, the pipe string friction changes. According to the number of friction changes, the placement depth of the combined tool string can be calculated. When it is determined that the combined tool string is placed at the designated position, the combined tool string is first lifted. Due to the action of the friction body 383, the guide pin 386 slides along the short track groove 323 to the reversing guide rail groove 324, and then the combined tool string is lowered. The guide pin 386 is switched to the long track groove 322 through the reversing guide rail groove 324 and slides. Since the track length of the long track groove 322 is greater than that of the short track groove 323, the annular protrusion 326 will exert a downward pushing force on the cone 36. The cone 36 pushes the second slip seat 371 to make the second slip tooth 372 clamped with the casing, thereby completing the clamping of the lower part of the perforation section. The main sealing rubber sleeve 33 is deformed under the extrusion action to achieve the sealing of the lower part of the perforation section.

[0111] Then, the pipe string is lifted to ensure that the telescopic piston pipe extends to the required length. The surface fracturing equipment supplies fracturing fluid into the pipe string. When the fracturing fluid passes through the throttling hole of the hydraulic internal pressure booster packer 2 with telescopic joints, a throttling pressure difference is formed. The fracturing fluid at the upper part of the throttling hole enters the piston cavity along the second hydraulic channel 212, pushes the piston to move upward, and compresses the first sealing rubber sleeve 22 to seal the annulus between the outer cylinder 24 and the casing. At this point, a double-sealing single-clamping fracturing sealing section is formed. The tension of the telescopic piston pipe 29 when it is extended is less than the friction force formed by the friction body 383 of the bottom packer. Otherwise, lifting the telescopic piston pipe 29 will cause the bottom packer to be unsealed. The lower periphery of the telescopic piston pipe 29 cylinder outer pipe has a pressure relief slit 2101, which allows the liquid to flow out between the telescopic piston pipe 29 and the cylinder outer pipe 210 when the second piston 28 is extended.

[0112] Finally, the high-pressure liquid in the casing enters the hydraulic drive assembly 12, pushes the two cone sleeves 125 to move axially towards each other, and radially spreads the first slip tooth 143 to be clamped on the inner wall of the casing. At this point, a double-sealing double-clamping perforation section sealing of the entire combined tool string is formed.

Claims

1. A combination tool with adjustable clamping distance for dragging fracturing in old wells, characterized in that: The tool string comprises, from top to bottom, a bidirectional hydraulic slip (1), a hydraulic inner pressure boosting packer (2) with an extension joint, a track type bottom packer (3) and a centralizing positioner (4); The bidirectional hydraulic slip (1) is used for being connected with the upper part of the perforation section; The hydraulic inner pressure boosting packer (2) with the extension joint comprises a hydraulic packer assembly and an extension assembly connected to the hydraulic packer assembly; The hydraulic packer assembly comprises a second central pipe (25) and an outer cylinder (24), and is used for sealing the upper part of the fracturing section of the oil well; The extension assembly comprises a cylinder outer pipe (210) and an extension piston pipe (29) arranged in the cylinder outer pipe (210); The cylinder outer pipe (210) of the extension assembly is fixed to the lower end of the outer cylinder (24); The top end of the extension piston pipe (29) is fixed with a second piston (28), and the second piston (28) is in sliding fit with the side wall of the inner cavity of the cylinder outer pipe (210); The inner side of the lower end of the cylinder outer pipe (210) is provided with a guide sleeve (211), the extension piston pipe (29) is in sliding fit with the inner side wall of the guide sleeve (211), and the second piston (28) can abut against the guide sleeve (211) when the extension piston pipe (29) slides to the maximum distance; The lower end of the cylinder outer pipe (210) is provided with a plurality of pressure relief slits (2101) extending in the axial direction, and the pressure relief slits (2101) are located at the position of the cylinder outer pipe (210) close to the guide sleeve (211), and the pressure relief slits (2101) pass through the cylinder outer pipe (210) in the radial direction; The second central pipe (25) is communicated with the extension piston pipe (29); The lower end of the extension piston pipe (29) has a thread for connecting with a joint section (31) of the track type bottom packer (3); The bidirectional hydraulic slip (1) has a first central pipe (13), the upper end of the second central pipe (25) of the hydraulic packer assembly is connected with the first central pipe (13); The centralizing positioner (4) is used for positioning the tool string when the tool string is lowered and ensuring that the tool string is in the center of the casing; The hydraulic packer assembly further comprises a second upper joint (21) arranged outside the second central pipe (25), a first sealing rubber sleeve (22) and a first piston (23); The first sealing rubber sleeve (22) is arranged between the second upper joint (21) and the outer cylinder (24), the upper end of the first piston (23) protrudes out of the outer cylinder (24) and abuts against the first sealing rubber sleeve (22), and the lower end of the first piston (23) protrudes into the outer cylinder (24) and is between the second central pipe (25); The hydraulic inner pressure boosting packer (2) with the extension joint further comprises a throttling assembly arranged between the hydraulic packer assembly and the extension assembly. The throttle assembly comprises a throttle sleeve (213), a magnetic seat (26) arranged inside the lower part of the throttle sleeve (213) and magnetically attracted to the second piston (28), and a throttle nozzle (27) arranged inside the magnetic seat (26); the throttle nozzle (27) has a throttle hole with a radial section diameter smaller than that of the second central pipe (25), and the throttle hole communicates the second central pipe (25) and the telescopic piston pipe (29); The throttle sleeve (213) is arranged between the outer cylinder (24) and the cylinder outer pipe (210); the upper section of the throttle sleeve (213) extends between the outer cylinder (24) and the second central pipe (25), the lower section extends between the cylinder outer pipe (210) and the magnetic seat (26), and the middle section protrudes outward and abuts against the outer cylinder (24) and the cylinder outer pipe (210); The throttle sleeve (213) has a fourth flow channel (2121); the fourth flow channel (2121) is arranged in the upper section of the throttle sleeve (213) and extends axially along the throttle sleeve (213) and penetrates the throttle sleeve (213) upwardly; the upper end of the upper section of the throttle sleeve (213) has a gap with the lower end of the first piston (23), and the gap communicates with the fourth flow channel (2121); A throttle sleeve is embedded in the lower part of the second central pipe (25), a plurality of third flow channels (2123) are arranged on the side wall of the throttle sleeve and penetrate the throttle sleeve in the radial direction; a second annular groove (2122) is arranged between the throttle sleeve and the middle section of the throttle sleeve (213), and the second annular groove (2122) communicates with the third flow channels (2123) and the fourth flow channel (2121).

2. The adjustable combination sliding and frac packer of claim 1, wherein: The width of the pressure relief slit (2101) is smaller than the particle diameter of the sand or ceramic particles used for fracturing in the oil well.

3. The adjustable combination tool for old well drag fracturing according to any one of claims 1-2, characterized in that: The bidirectional hydraulic slip (1) comprises a first upper joint (11), a first central pipe (13), a plurality of bidirectional slip assemblies (14) arranged outside the first central pipe (13), hydraulic drive assemblies (12) symmetrically arranged at the upper end and the lower end of the bidirectional slip assemblies (14), and a first lower joint (15); The plurality of bidirectional slip assemblies (14) are uniformly distributed along the central axis of the first central pipe (13); the inner side of the bidirectional slip assembly (14) is provided with an inner conical surface; The hydraulic drive assembly (12) comprises a compression sleeve (121), a first connecting sleeve (122), a support ring (123), a second connecting sleeve (124), and a conical sleeve (125); One end of the compression sleeve (121) and the first connecting sleeve (122) of one of the hydraulic drive assemblies (12) is connected to the first upper joint (11); one end of the compression sleeve (121) and the first connecting sleeve (122) of the other hydraulic drive assembly (12) is connected to the first lower joint (15); the other end of the first connecting sleeve (122) and the conical sleeve (125) have a gap therebetween; The other end of the conical sleeve (125) is provided with an outer conical surface matched with the inner conical surface of the bidirectional slip assembly (14); the first connecting sleeve (122) and the second connecting sleeve (124) are axially connected in series; The middle part of the first connecting sleeve (122) is sealingly connected with a support ring (123), and a first flow channel extending in the axial direction of the support ring (123) and penetrating through the side wall of the support ring (123) in the radial direction is arranged on the side wall of the support ring (123); The inner side of the first connecting sleeve (122) has a ring cavity and a second flow channel penetrating through the first connecting sleeve (122) in the axial direction and towards the double-acting slip assembly (14), and the first flow channel, the ring cavity and the second flow channel form a first hydraulic channel, which is used to drive the cone sleeve (125) to compress the double-acting slip assembly (14) to realize sealing under the action of high-pressure liquid.

4. The adjustable combination tool of claim 3, wherein: The track type bottom sealing packer (3) comprises a joint section (31) and a central rod (32) connected below the joint section (31) which are sequentially connected from top to bottom; and further comprises a main sealing rubber sleeve (33), a conical body, a slip assembly (37) and a centralizer assembly (38) which are sequentially sleeved outside the central rod (32) from top to bottom. The joint section (31) comprises an upper connecting section for connecting with the oil pipe, a lower connecting section connected with the central rod (32) and a pressure-guiding sand blasting assembly arranged between the upper connecting section and the lower connecting section. The pressure-guiding sand blasting assembly comprises a plurality of guide sand outlets (312) uniformly distributed in the circumferential direction. The centralizer assembly (38) comprises a centralizer main body (381), the centralizer main body (381) is provided with a mounting groove (3811), a friction body (383) for frictionally cooperating with the casing is arranged in the mounting groove (3811), and the lower end of the centralizer assembly (38) is provided with an inwardly protruding guide pin (386); The outer surface of the lower section of the central rod (32) is provided with guide grooves in the axial direction; the guide grooves comprise a plurality of long guide grooves (322) and a plurality of short guide grooves (323) extending in the axial direction, and a reversing guide groove (324) connecting the lower ends of the long guide grooves (322) and the lower ends of the short guide grooves (323); the long guide grooves (322) and the short guide grooves (323) are arranged at intervals in the circumferential direction. The guide pin (386) cooperates with the guide groove.

5. The adjustable combination sliding and frac packer of claim 4, wherein: The slip assembly (37) comprises a plurality of slip assemblies, each slip assembly comprising a second slip seat (371), a plurality of second slip teeth (372) and a second slip tooth retracting spring (373), the upper end of the second slip tooth (372) extending out of the upper end of the second slip seat (371), and the lower end of the second slip tooth (372) being connected in the second slip seat (371) through the second slip tooth retracting spring (373); The second slip seat (371) is connected with the centralizer main body (381).

6. The adjustable combination sliding and frac packer of claim 5, wherein: The conical body comprises a conical cap (35) surrounding the central rod (32) and a conical body (36) connected below the conical cap (35); the conical cap (35), the conical body (36) and the central rod (32) form a first mounting cavity (314); The central rod (32) is provided with an annular protrusion (326) arranged in the first mounting cavity (314); The guide pin (386) cooperates with the top end of the short guide rail groove (323), and the annular protrusion (326) is in clearance with the lower inner surface of the first mounting cavity (314); Alternatively, the guide pin (386) cooperates with the top end of the long guide rail groove (322), and the annular protrusion (326) pushes down to insert the cone (36) between the slip teeth and the center rod (32).

7. The adjustable combination sliding and frac packer of claim 6, wherein: The centralizer (4) comprises a guide centralizer assembly and a plurality of positioning assemblies fixedly connected; The guide centralizer assembly comprises a centralizer body (41), a connecting groove (4121) arranged on the centralizer body (41), and a plurality of lower limit grooves (4122) arranged in the connecting groove (4121); The positioning assembly comprises a positioning body (43), a limiting groove arranged on the positioning body (43), and an upper limiting groove (432) arranged correspondingly to the lower limiting groove (4122); A compression spring (45) is arranged in the cavity composed of the lower limiting groove (4122) and the upper limiting groove (432), and an elastic member is arranged between the limiting groove and the connecting groove (4121) to support the positioning body (43) and make the positioning body (43) float in the radial direction.

8. The adjustable combination sliding and frac packer of claim 7, wherein: The positioning body (43) comprises a positioning protrusion (433), and a first guide section (435) and a second guide section (436) arranged on both sides of the positioning protrusion (433), and the end face of the positioning protrusion (433) is a circular arc face.

Images