Small-diameter fishable preset blocking device for three-pipe separate injection well and preset blocking method

Abstract

The invention belongs to the technical field of oil production engineering in the oil industry, and discloses a small-diameter salvageable preset blocking device for a three-pipe separate injection well and a preset blocking method.The center rod of the device penetrates into the lower end of a center hole of a rubber sleeve base, a boss is arranged at the lower end of the center rod, and the center rod is hung at an inner circular bead at the upper end of the rubber sleeve base through the boss; the sealing component is sleeved from the lower end of the rubber sleeve seat; the guide head is in screwed connection with the rubber sleeve seat; the fishing head and the center rod are connected through a screw thread by the connecting sleeve; the locking claw penetrates from the lower end of the upper cylinder and stops when an outer boss section at the lower end of the locking claw enters an expanding section at the lower end of the upper cylinder and encounters resistance; the upper barrel body and the locking claw which are installed together are sleeved from the upper end of the fishing head, the upper end of the locking claw is connected with the diameter expanding section of the fishing head through the shear pin, the connecting sleeve corresponds to the lower end of the locking claw, and the lower barrel body is sleeved from the lower end of the connected blanking plug and is in threaded connection with the upper barrel body. The operation problem of controlling the pressure in the oil pipe in the tripping-in process of small-diameter oil pipe operation under pressure is solved, and the well control requirement is met.

Description

Technical Field

[0001] The invention belongs to the technical field of oil production engineering in the petroleum industry, and relates to a small-diameter fishable pre-setting plugging device and a pre-setting plugging method for a three-pipe injection well. Background Art

[0002] The oil field stratified water injection mainly solves the contradiction between layers and the problem of uneven water absorption in each layer, achieves uniform displacement of injection and production, and improves the final recovery rate. The three-pipe injection technology is a new stratified water injection technology developed by petroleum engineering technicians in recent years. Its process principle is to use the casing and 2 7 / 8″ oil pipe annulus injection into the first section (upper section), at 2 7 / 8″ tubing and 1.9″ tubing annulus are injected into the second section (middle section), and 1.9″ tubing is injected into the third section (lower section). The specific operation is to run 2 7 / 8″ tubing, the lower part of the tubing corresponds to the barrier of the water injection layer section and is connected with two sets of packers for isolating the water injection layer section; a water distributor is arranged between the packers for water injection in the middle layer section; the water distributor has an inner sealing section for cooperating with the sealing plug of the central injection string to achieve sealing; the central injection string adopts 1.9″ tubing, and the lower part is connected with the sealing plug.

[0003] A three-pipe injection wellhead device is installed at the wellhead to control the water injection volume of each section. This process can adjust the injection volume at the wellhead, which is convenient and fast. However, due to the high-pressure water injection of the injection well all year round, the wellhead pressure is high, and the pressure operation technology is often used to pull the pipe string. Pressure operation can ensure the stability of water injection pressure, the balance of injection and production system, and the stability of oil well production. However, compared with the conventional water injection process, the three-pipe injection process requires 2 7 / 8″ oil pipe into 1.9″ oil pipe. The technology of 1.9″ oil pipe under pressure operation is not mature, especially the pressure control technology in the oil pipe has no effective solution, which hinders the further promotion and application of this technology. Summary of the invention

[0004] In order to solve the above problems, the technical solution adopted by the present invention is to provide a small-diameter fishable pre-set plugging device and a pre-set plugging method for a three-pipe injection well, which realizes the blowout prevention in the tubing during the 1.9″ tubing under pressure operation, meets the well control requirements, and realizes safe and environmentally friendly operations.

[0005] The technical solution of the present invention is:

[0006] A small-diameter salvageable pre-set plugging device for a three-tube injection well comprises a pre-set working cylinder and a pre-set plugging device. The pre-set plugging device comprises a salvaging head, a locking claw, a connecting sleeve, a center rod, a rubber cylinder seat, a sealing assembly and a guide head from top to bottom.

[0007] The center rod is inserted from the lower end of the center hole of the rubber cylinder seat, and there is a boss at the lower end of the center rod, which is hung on the inner shoulder of the upper end of the rubber cylinder seat through the boss; the sealing assembly is inserted from the lower end of the rubber cylinder seat, and the two sets of sealing parts are in opposite directions to achieve bidirectional pressure bearing; the guide head is connected to the rubber cylinder seat by thread; the connecting sleeve connects the salvage head and the center rod by thread; the locking claw is inserted from the lower end of the upper cylinder body, and when the outer boss section at the lower end of the locking claw enters the expanded diameter section at the lower end of the upper cylinder body and stops when encountering resistance; the upper cylinder body and the locking claw that are installed together are inserted from the upper end of the salvage head, and the upper end of the locking claw is connected to the expanded diameter section of the salvage head by shear nails. At this time, the connecting sleeve corresponds to the lower end of the locking claw, supporting the inner diameter of the locking claw to prevent the locking claw from being forced to retract inward; the lower cylinder body is inserted from the lower end of the connected plug and is connected to the upper cylinder body by thread.

[0008] Furthermore, the preset working cylinder includes an upper cylinder and a lower cylinder, which are connected by threads; the inner hole at the lower end of the upper cylinder has an expanded diameter section, and the outer diameter of the upper end is threaded, which is used to connect with the 1.9" oil pipe; the inner hole at the lower end of the lower cylinder has a reduced diameter section, and the outer diameter of the lower end is threaded, which is used to connect with the sealing plug.

[0009] Furthermore, the packer A and the packer B are of compression type.

[0010] Furthermore, the sealing assembly is composed of two groups of V-shaped end rings, a V-shaped spacer ring, a middle spacer ring and a V-shaped sealing ring.

[0011] Furthermore, the V-shaped sealing ring is made of rubber material.

[0012] Furthermore, the V-shaped end rings, V-shaped spacer rings and middle spacer rings are made of polytetrafluoroethylene material.

[0013] A small-diameter, fishable pre-plugging method for a three-pipe injection well comprises the following steps:

[0014] Step 1, wellbore preparation: complete the process of well cleaning, sand flushing, scraping, etc. when the wellbore is empty to ensure the integrity of the wellbore and the smooth running of the water injection string;

[0015] Step 2: Place 2 in the well to be constructed. 7 / 8″ oil pipe string; from bottom to top: constant pressure sliding sleeve, 2 7 / 8″ oil pipe, packer A, plug-in water distributor, packer B, 2 7 / 8″ oil pipe; constant pressure sleeve control 2 7 / 8″The internal pressure of the tubing when the tubing is lowered into the well forms a pressure-bearing and sealed system when the packer is set, providing the conditions for the packer to be set;

[0016] Step 3, setting packer A and packer B; connecting the surface pressure equipment and pipelines; starting the pump truck to pressurize and set the downhole packer; increasing the pressure of the pump truck to open the constant pressure sliding sleeve;

[0017] Step 4, in 2 7 / 8″ oil pipe is put into 1.9″ oil pipe; the 1.9″ oil pipe string is composed of sealing cannula, pre-set plug and 1.9″ oil pipe from bottom to top;

[0018] Step 5, in step 4, the rubber cylinder seat, the sealing assembly and the guide head and other components move upward under the downhole pressure to the lower end of the locking claw, and the locking claw is fixed in the upper cylinder due to the internal support of the connecting sleeve; the plug is preset to seal the pressure in the 1.9″ oil pipe;

[0019] Step 6: In step 4, after the 1.9″ oil pipe is lowered to the predetermined position, the sealing insert is passed through the plug-in water distributor to achieve 2 7 / 8" oil pipe and 1.9" oil pipe are sealed; open 2 7 / 8″ water distributor on the oil pipe;

[0020] Step 7, using a steel wire to salvage the preset plug; the lower end of the steel wire is connected to a weighted rod and a salvage device in sequence; the salvage device salvages the salvage head of the plug;

[0021] Step 8: In step 7, the steel wire is lifted up and the shear nail is cut off; the connecting sleeve moves up with the fishing head and the center rod to the inner shoulder of the upper end of the locking claw, giving the locking claw an upward force, and the locking claw loses its inner support, retracts, and moves upward;

[0022] Step 9, in step 7, the boss at the lower end of the center rod moves upward to the inner shoulder at the upper end of the rubber cylinder seat, driving the preset plug upward and lifting it out of the sealing section;

[0023] Step 10: Use wireline operation to lift the preset plug out of the wellbore; the operation is completed.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The problem of controlling the pressure in the oil pipe during the operation of running a small-diameter oil pipe under pressure is solved, and overflow or blowout during the operation is avoided, meeting the well control requirements. After the pipe string is put into the well, the plug is pulled out of the wellbore by wire operation to ensure the diameter of the water injection channel and realize effective water injection. The present invention can promote the on-site promotion and application of the three-pipe injection process technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] When considered in conjunction with the accompanying drawings, the present invention can be more completely understood and many of the accompanying advantages can be easily known by referring to the following detailed description, but the drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations of the present invention, wherein:

[0027] Figure 1 This is a schematic diagram of the tubing string structure for the three-tube split injection process;

[0028] Figure 2 It is a schematic diagram of the structure of the preset working cylinder;

[0029] Figure 3 It is a schematic diagram of the structure of the preset plug in a sealed state;

[0030] Figure 4 It is a schematic diagram of the structure of the preset plug in the salvage state;

[0031] Figure 5 It is a schematic diagram of the locking claw structure;

[0032] Figure 6 It is a schematic diagram of the sealing component structure.

[0033] In the figure, 1: casing, 2:2 7 / 8″ oil pipe, 3: 1.9″ oil pipe, 4: first water injection layer section, 5: second water injection layer section, 6: third water injection layer section, 7: packer A, 8: pre-set plug, 9: plug-in water distributor, 10: sealing plug, 11: packer B, 12: constant pressure sliding sleeve, 13: upper cylinder, 14: lower cylinder, 15: fishing head, 16: shear nail, 17: locking claw, 18: connecting sleeve, 19: center rod, 20: rubber cylinder seat, 21: sealing assembly, 21.1: V-type end ring, 21.2: V-type spacer ring, 21.3: middle spacer ring, 21.4: V-type sealing ring, 22: guide head. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described in detail below in conjunction with the drawings in the embodiments of the present invention. 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.

[0035] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred parts must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0036] Example 1

[0037] like Figure 2-6 As shown, a small-diameter, fishable pre-plugging device for a three-tube injection well is shown, and the tool comprises a pre-setting working cylinder and a pre-setting plugging device 8.

[0038] The preset working cylinder includes an upper cylinder 13 and a lower cylinder 14, which are connected by threads; the lower end inner hole of the upper cylinder 13 has an enlarged diameter section, and the upper end outer diameter is threaded, which is used to connect with the 1.9" oil pipe; the lower end inner hole of the lower cylinder 14 has a reduced diameter section, and the lower end outer diameter is threaded, which is used to connect with the sealing insert 10;

[0039] The plug includes a fishing head 15, a locking claw 17, a connecting sleeve 18, a center rod 19, a rubber cartridge seat 20, a sealing assembly 21 and a guide head 22 from top to bottom; the center rod 19 is inserted from the lower end of the center hole of the rubber cartridge seat 20, and the lower end of the center rod 19 has a boss, which can be hung on the inner shoulder of the upper end of the rubber cartridge seat 20; the sealing assembly 21 is inserted from the lower end of the rubber cartridge seat 20, and the sealing assembly 21 is composed of two groups of V-shaped end rings 21.1, V-shaped spacer rings 21.2, middle spacer rings 21.3 and V-shaped sealing rings 21.4, the V-shaped sealing rings 21.4 are made of rubber material, and the V-shaped end rings 21.1, V-shaped spacer rings 21.2 and middle spacer rings 21.3 are made of polytetrafluoroethylene material; the two groups of sealing parts are in opposite directions, To achieve bidirectional pressure bearing; the guide head 22 and the rubber cylinder seat 20 are connected by thread; the connecting sleeve 18 connects the fishing head 15 and the center rod 19 by thread connection; the locking claw 17 is inserted from the lower end of the upper cylinder 13, and stops when the outer boss section at the lower end of the locking claw 17 enters the enlarged diameter section at the lower end of the upper cylinder 13; the upper cylinder 13 and the locking claw 17 installed together are inserted from the upper end of the fishing head 15, and the upper end of the locking claw 17 is connected to the enlarged diameter section of the fishing head 15 by shear nails 16. At this time, the connecting sleeve 18 corresponds to the lower end of the locking claw 17, supporting the inner diameter of the locking claw 17 to prevent the locking claw 17 from being retracted by force; the lower cylinder 14 is inserted from the lower end of the connected plug and connected to the upper cylinder 13 by thread connection. At this time, it is in the state of downhole sealing.

[0040] Example 2

[0041] like Figure 1-5 As shown, based on Example 1, the following steps are included:

[0042] Step 1, wellbore preparation: complete the process of well cleaning, sand flushing, scraping, etc. when the wellbore is empty to ensure the integrity of the wellbore and the smooth running of the water injection string;

[0043] Step 2: Place 2 in the well to be constructed. 7 / 8″ oil pipe string; from bottom to top: constant pressure sliding sleeve 12, 2 7 / 8″ oil pipe 2, packer 7, plug-in water distributor 10, packer 11, 2 7 / 8″ oil pipe 2; packers 7 and 11 are compression type; constant pressure sliding sleeve 12 controls 2 7 When the / 8″ tubing string is lowered into the well, the internal pressure of the tubing forms a pressure-bearing sealing system, providing the sealing conditions for the packer 11;

[0044] Step 3, setting the packer A7 and the packer B11; connecting the surface pressure equipment and pipelines; starting the pump truck to pressurize and set the downhole packers 7 and 11; increasing the pressure of the pump truck to open the constant pressure sleeve 12;

[0045] Step 4, in 2 7 A 1.9" oil pipe 3 is lowered into the 8" oil pipe 2; the 1.9" oil pipe string is composed of a sealing insert 10, a pre-set plug 8, and a 1.9" oil pipe 3 from bottom to top;

[0046] Step 5, in step 4, the rubber cylinder seat 20, the sealing assembly 21 and the guide head 22 and other components move upward under the downhole pressure to the lower end of the locking claw 17, and the locking claw 17 is fixed in the upper cylinder 13 due to the internal support of the connecting sleeve 18; the preset plug 8 seals the pressure in the 1.9" oil pipe 3;

[0047] Step 6: In step 4, after the 1.9″ oil pipe 3 is lowered to the predetermined position, the sealing insert 10 passes through the plug-in water distributor 9 to achieve 2 7 / 8" oil pipe 2 and 1.9" oil pipe 3 are sealed; open 2 7 / 8″ inserted water distributor 9 on oil pipe 2;

[0048] Step 7, using a steel wire to salvage the preset plug 8; the lower end of the steel wire is connected to a weighting rod and a salvage device in sequence; the salvage device salvages the salvage head 15 of the plug;

[0049] Step 8, in step 7, the steel wire is lifted up, and the shear nail is cut off 16; the connecting sleeve 18 moves up along with the assembly of the fishing head 15 and the center rod 19 to the inner shoulder of the upper end of the locking claw 17, giving the locking claw 17 an upward force, and the locking claw 17 loses its inner support, retracts, and moves upward;

[0050] Step 9, in step 7, the boss at the lower end of the center rod 19 moves upward to the inner shoulder at the upper end of the rubber cylinder seat 20, driving the preset plug 8 upward and lifting it out of the sealing section;

[0051] Step 10, the wireline operation preset plug 8 is lifted out of the wellbore; the operation is completed.

[0052] The basic principles and main features of the present invention and the advantages of the present invention are shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description. Therefore, it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention, and any figure marks in the claims should not be regarded as limiting the claims involved.

[0053] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A small-diameter, fishable pre-plugging device for a three-pipe injection well, comprising a pre-plugging working cylinder and a pre-plugging device (8), characterized in that: The preset plug (8) comprises, from top to bottom, a fishing head (15), a locking claw (17), a connecting sleeve (18), a center rod (19), a rubber cylinder seat (20), a sealing assembly (21) and a guide head (22).

2. The small-diameter, fishable pre-plugging device for three-pipe injection wells according to claim 1 is characterized in that: The center rod (19) is inserted from the lower end of the center hole of the rubber cartridge seat (20), and the lower end of the center rod (19) has a boss, which is hung on the inner shoulder of the upper end of the rubber cartridge seat (20) through the boss; the sealing assembly (21) is inserted from the lower end of the rubber cartridge seat (20), and the two sets of sealing components are in opposite directions to achieve bidirectional pressure bearing; the guide head (22) is connected to the rubber cartridge seat (20) by thread; the connecting sleeve (18) connects the fishing head (15) and the center rod (19) by thread; the locking claw (17) is inserted from the lower end of the upper cylinder (13), and when the locking claw ( The outer boss section at the lower end of the upper cylinder (17) enters the enlarged diameter section at the lower end of the upper cylinder (13) and stops when encountering resistance; the upper cylinder (13) and the locking claw (17) installed together are inserted from the upper end of the fishing head (15), and the upper end of the locking claw (17) is connected to the enlarged diameter section of the fishing head (15) by a shear nail (16). At this time, the connecting sleeve (18) corresponds to the lower end of the locking claw (17), supports the inner diameter of the locking claw (17), and prevents the locking claw (17) from being retracted by force; the lower cylinder (14) is inserted from the lower end of the connected plug and is threadedly connected to the upper cylinder (13).

3. The small-diameter, fishable pre-plugging device for three-pipe injection wells according to claim 1 is characterized in that: The preset working cylinder comprises an upper cylinder (13) and a lower cylinder (14), which are connected by threads; the inner hole at the lower end of the upper cylinder (13) has an enlarged diameter section, and the outer diameter of the upper end is a thread, which is used to connect with the 1.9" oil pipe (3); the inner hole at the lower end of the lower cylinder (14) has a reduced diameter section, and the outer diameter of the lower end is a thread, which is used to connect with the sealing insert (10).

4. The small-diameter, fishable pre-plugging device for three-pipe injection wells according to claim 1 is characterized in that: The sealing assembly (21) is composed of two groups of V-shaped end rings (21.1), a V-shaped spacer ring (21.2), a middle spacer ring (21.3) and a V-shaped sealing ring (21.4).

5. The small-diameter, fishable pre-plugging device for three-pipe injection wells according to claim 4 is characterized in that: The V-shaped sealing ring (21.4) is made of rubber material.

6. The small-diameter, fishable pre-plugging device for three-pipe injection wells according to claim 4 is characterized in that: The V-shaped end ring (21.1), the V-shaped spacer ring (21.2) and the middle spacer ring (21.3) are made of polytetrafluoroethylene material.

7. The plugging method of the small-diameter bailed-out pre-placed plugging device for three-pipe injection wells according to claim 1 is characterized in that: The following steps are involved: Step 1, wellbore preparation: complete the process of well cleaning, sand flushing, scraping, etc. when the wellbore is empty to ensure the integrity of the wellbore and the smooth running of the water injection string; Step 2: Lower the 2 7 / 8″ oil pipe (2); from bottom to top: constant pressure sleeve (12), 2 7 / 8″ oil pipe (2), packer A (7), plug-in water distributor (9), packer B (11), 2 7 / 8″ oil pipe (2); constant pressure sleeve (12) control 2 7 / 8″ oil pipe (2) when it is lowered into the well, forms a pressure-bearing closed system when the packer is set, and forms a pressure-bearing sealing system to provide the packer setting conditions; Step 3, setting the packer A (7) and the packer B (11); connecting the surface pressure equipment and pipelines; starting the pump truck to pressurize and set the downhole packer; increasing the pressure of the pump truck to open the constant pressure sliding sleeve; Step 4, in 2 7 A 1.9" oil pipe (3) is lowered into the 8" oil pipe (2); the 1.9" oil pipe (3) comprises a sealing insert (10), a pre-set plug (8), and a 1.9" oil pipe (3) from bottom to top; Step 5, in step 4, the rubber cylinder seat (20), the sealing assembly (21) and the guide head (22) and other components move upward under the action of downhole pressure and abut against the lower end of the locking claw (17), and the locking claw (17) is fixed in the upper cylinder (13) due to the internal support of the connecting sleeve; the plug (8) is preset to seal the internal pressure of the 1.9" oil pipe (3); Step 6, in step 4, after the 1.9″ oil pipe (3) is lowered to the predetermined position, the sealing insert (10) passes through the plug-in water distributor (9) to achieve 2 7 / 8" oil pipe (2) and 1.9" oil pipe (3) are sealed; at the same time, open 2 7 / 8″ water distributor on the oil pipe (2); Step 7, using a steel wire to salvage the pre-set plug (8); the lower end of the steel wire is connected to a weighting rod and a salvage device in sequence; the salvage device salvages the salvage head of the plug; Step 8, in step 7, the steel wire is lifted up and the shear nail is cut off; the connecting sleeve (18) moves up along with the fishing head (15) and the center rod (19) to the inner shoulder of the upper end of the locking claw (17), giving the locking claw (17) an upward force, and the locking claw (17) loses its inner support, retracts, and moves upward; Step 9, in step 7, the boss at the lower end of the center rod (19) moves upward to the inner shoulder at the upper end of the rubber cylinder seat (20), driving the preset plug (8) upward and lifting it out of the sealing section; Step 10, wire work is used to lift the pre-set plug (8) out of the wellbore; the operation is completed.

8. The plugging method of the small-diameter bailed-out pre-placed plugging device for three-pipe injection wells according to claim 7 is characterized in that: The packer A (11) and the packer B (11) are of compression type.

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