Crack sealing tools and crack sealing methods

Abstract

The present invention provides a fracture-hole plugging tool comprising a base pipe, a disconnect tool connected downstream of the base pipe, and a self-expanding plugging layer mounted on the base pipe. The self-expanding plugging layer is configured to expand under downhole conditions to seal downhole leakage points. The disconnect tool is configured to initially radially extend to support the self-expanding plugging layer and to radially retract after the self-expanding plugging layer has expanded. The present invention also provides a corresponding fracture-hole plugging method.

Description

Technical Field

[0001] The present invention relates to oil and gas well completion technology, and more particularly to a fracture and hole plugging tool and a fracture and hole plugging method using the fracture and hole plugging tool. Background Art

[0002] Lost circulation is a common problem in drilling operations. In particular, serious losses occur when drilling into faults, large fractures, and karst caves. These losses often manifest as fluid loss, preventing drilling progress, and can even lead to wellbore collapse, stuck pipe, overflows, or blowouts. This poses a significant threat to drilling operations. With the continued expansion of exploration and development of fractured-cavity oil and gas reservoirs both domestically and internationally, lost circulation in fractured-cavity carbonate and fault-karst areas is becoming increasingly severe, with frequent instances of mud loss.

[0003] In existing technologies, leak plugging of fractures and holes in oil and gas wells primarily involves high-concentration conventional plugging slurries, bridge plugging, cement slurry plugging, and chemical gel plugging. However, these methods have significant drawbacks and deficiencies for leaks from larger fractures and karst caves. In particular, these methods fail to effectively retain fluid within fractures and holes, are expensive, require lengthy installation times, and can easily lead to complications at the well bottom.

[0004] Therefore, it is necessary to provide an effective crack and hole plugging tool. Summary of the Invention

[0005] To address the aforementioned technical issues, the present invention aims to provide a fracture-hole plugging tool that can plug larger fractures and holes during oil and gas well completion while simultaneously providing wellbore support. The present invention also aims to provide a method for plugging fractures and holes using this tool.

[0006] According to a first aspect of the present invention, a fracture-hole plugging tool is provided, comprising a base pipe, a disconnect tool connected downstream of the base pipe, and a self-expanding plugging layer mounted on the base pipe. The self-expanding plugging layer is configured to expand under downhole conditions to seal downhole leakage points. The disconnect tool is configured to initially radially extend to support the self-expanding plugging layer in a first state, and radially retract after the self-expanding plugging layer has expanded in a second state.

[0007] In one embodiment, the disconnection tool includes a piston cylinder capable of axial movement within the disconnection tool, and a support mechanism connected to the piston cylinder. In a first state, the support mechanism radially extends to support the self-expanding plugging layer, and in a second state, the support mechanism radially retracts in response to the axial movement of the piston cylinder.

[0008] In one embodiment, the disconnect tool comprises an outer cylinder and an inner cylinder, with the piston cylinder disposed between the outer cylinder and the inner cylinder. In a first state, the piston cylinder is secured within the outer cylinder by shear pins, while in a second state, the shear pins are sheared, allowing the piston cylinder to move axially between the outer cylinder and the inner cylinder.

[0009] In one embodiment, the support mechanism includes a support rod, the radial inner end of the support rod is hinged on the outer wall of the inner cylinder, and the radial outer end of the support rod can pass through the first waist-shaped through hole on the outer cylinder to radially extend and retract.

[0010] In one embodiment, a second waist-shaped hole is formed on the support rod, and a sliding pin inserted into the second waist-shaped hole is provided at the downstream end of the piston cylinder.

[0011] In one embodiment, the disconnect tool comprises an upper connection sleeve for connecting to the base pipe and a lower joint having a ball seat formed therein, wherein the disconnect tool is capable of transitioning from a first state to a second state in response to a build-up of pressure caused by dropping a ball into the ball seat.

[0012] In one embodiment, the outer cylinder and the inner cylinder are fixedly connected to the upper connecting sleeve and the lower joint at the upstream end and the downstream end respectively.

[0013] In one embodiment, the self-expanding plugging layer is made of a shape memory composite material, preferably a shape memory rigid polyurethane foam.

[0014] In one embodiment, the crack and hole plugging tool further includes an upper joint, and the self-expanding plugging layer is axially located between the upper joint and the disconnecting tool.

[0015] According to another aspect of the present invention, a fracture plugging method is also provided, comprising the steps of: lowering the fracture plugging tool as described above into a leakage point in a wellbore, wherein a support rod of a support mechanism of the fracture plugging tool extends radially to support a self-expanding plugging layer of the fracture plugging tool; inducing the self-expanding plugging layer to expand and seal the leakage point in the wellbore; throwing a ball into the fracture plugging tool so that the ball sits on a ball seat in a lower joint of the fracture plugging tool; shearing a shear pin between an outer cylinder and a piston cylinder of the fracture plugging tool by holding down pressure, causing the piston cylinder to move axially downstream, thereby causing the support rod to retract radially; and lifting the fracture plugging tool out of the wellbore.

[0016] The fracture and hole plugging tool according to the present invention can achieve efficient plugging, and has a simple structure, safety and reliability. At the same time, after completing the plugging operation, the fracture and hole plugging tool according to the present invention can be very conveniently recovered from the wellbore through simple operations. When used in an open hole well, the self-expanding plugging layer of the fracture and hole plugging tool according to the present invention can not only achieve plugging after expansion, but also play a role in supporting the open hole well wall, maintaining the well wall stability and preventing the well wall from collapsing. In addition, the self-expanding plugging layer of the fracture and hole plugging tool according to the present invention can be tightly fitted at the leakage point by expansion, which can ensure that the original wellbore size is not affected, so that subsequent drilling or other operations can be completed after the leakage layer is plugged.

[0017] In addition, the construction process of the fracture hole plugging method according to the present invention is simple, does not require large-scale ground equipment, is conducive to promotion and application in various well types, and avoids the consumption of a large amount of expensive plugging materials and processing time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be described below with reference to the accompanying drawings. In the accompanying drawings:

[0019] Figure 1 The overall structure of the crack and hole plugging tool according to the present invention is schematically shown;

[0020] Figure 2 Schematic diagram showing Figure 1 The structure of the disconnecting device of the crack and hole plugging tool shown, wherein the disconnecting device is in a state before disconnection;

[0021] Figure 3 Schematic diagram showing Figure 1 The disconnecting device of the crack and hole plugging tool shown is in the state after disconnection;

[0022] Figures 4A to 4D The various steps of the crack hole plugging method according to the present invention are shown.

[0023] In this application, all drawings are schematic drawings, are only used to illustrate the principle of the present invention, and are not drawn according to actual scale. In all drawings, the same reference numerals are used to represent the same parts or structures. DETAILED DESCRIPTION

[0024] The present invention is described below with reference to the accompanying drawings. For ease of understanding, in this application, the direction close to the wellhead is defined as the upper end, upstream, or similar terms, while the direction away from the wellhead is defined as the lower end, downstream, or similar terms. Furthermore, the direction along the length of the fracture and hole plugging tool is referred to as the longitudinal direction, axial direction, or similar terms, while the direction perpendicular thereto is referred to as the transverse direction, radial direction, or similar terms.

[0025] Figure 1The overall structure of the crack and hole plugging tool 100 according to the present invention is shown. Figure 1 As shown, the fracture and hole plugging tool 100 according to the present invention includes a cylindrical base pipe 2. The base pipe 2 is constructed to be hollow and is used for allowing downhole fluid to flow therethrough. A top joint 1 is connected to the upper end of the base pipe 2 for connecting to other functional short sections (not shown) in the pipe string. A sealing ring 3 is provided in the connection area between the base pipe 2 and the top joint 1 to form a seal therebetween. A disconnect device 5 is connected to the lower end of the base pipe 2. The connection between the base pipe 2, the top joint 1, and the disconnect device 5 can be achieved by a conventional oil casing joint.

[0026] According to the present invention, a self-expanding plugging layer 4 is sleeved on the outer circumference of the base pipe 2. Figure 1 As shown, in the axial direction, the self-expanding plugging layer 4 is defined by the upper connector 1 located upstream thereof and the extended support mechanism 60 of the disconnecting device 5 located downstream thereof. During the lowering of the fracture and hole plugging tool 100, the self-expanding plugging layer 4 is supported by the support mechanism 60 of the disconnecting device 5 located downstream thereof (which will be described in detail below), thereby enabling smooth lowering into the fracture and hole to be plugged.

[0027] According to one embodiment of the present invention, the self-expanding plugging layer 4 is made of a temperature-sensitive shape memory composite material. In a specific example, the self-expanding plugging layer 4 can be compressed on the ground by a specially designed compression molding device and then sleeved on the base pipe 2, and supported on the base pipe 2 by a disconnecting device 5 (specifically, the support mechanism 60 of the disconnecting device 5). After being lowered to the target position, the self-expanding plugging layer 4 can be stimulated under downhole conditions (with specific temperature and pressure) and expand radially outward unidirectionally, thereby sticking to malignant leakage points such as caves and cracks. In this way, the self-expanding plugging layer 4 can compensate for the well wall and fill the annulus. During the expansion process, the sleeve joint between the self-expanding plugging layer 4 and the base pipe 2 gradually loses its function. However, the disconnecting device 5 located below the base pipe 2 can continue to support the self-expanding plugging layer 4 set on the outside of the base pipe 2, ensuring the smooth expansion of the self-expanding plugging layer 4.

[0028] Those skilled in the art will readily understand that by selecting a suitable length of the self-expanding plugging layer 4, the cracks and holes that need to be plugged can be fully covered, thereby achieving a reliable plugging effect.

[0029] According to the present invention, the shape memory composite material can be made of polymers having a soft and hard segment structure and a certain glass transition temperature, such as polyurethane, polyisoprene, and polyetherthioketone. In a preferred embodiment, polyurethane rigid foam is used to prepare the shape memory composite material.

[0030] Preferably, the shape-memory rigid polyurethane foam uses ε-caprolactone as a monomer and one or more of glycerol, trimethylolpropane, ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol as initiators to synthesize a polymer polyol. Water and dichloromethane are used as blowing agents. This preparation method is simple to operate, and the resulting rigid polyurethane foam exhibits shape memory, a high recoverable deformation rate, fast deformation and recovery rates, and excellent properties such as high hardness and low density.

[0031] In a specific embodiment, the shape memory rigid polyurethane foam is composed of the following raw materials in parts by weight: 25-60 parts of polymer polyol, 80-135 parts of modified isocyanate mixture, 5.5-7.5 parts of aliphatic or aromatic chain extender, 3.5-7.5 parts of composite foaming agent, 1.0-3.0 parts of foam stabilizer, 1.5-3.5 parts of pore structure regulator, 0.5-1.5 parts of composite catalyst, and 0.5-1.5 parts of filler.

[0032] In another specific embodiment, a shape-memory rigid polyurethane foam is composed of component A and component B in a certain proportion. Component A comprises the following components: a polymer polyol, an aliphatic or aromatic chain extender, a composite foaming agent, a foam stabilizer, a cell structure regulator, a composite catalyst, and a filler; and component B is a modified isocyanate mixture.

[0033] According to the present invention, the material hardness of the shape memory rigid polyurethane foam is 30-70 Shore D hardness, the compression strength is 3-4.5 MPa, the open porosity is 80-90%, and the density is 0.2-0.4 g / cm 3 , the shape sensitive temperature of the material is 50 ~ 120 ℃.

[0034] In a preferred embodiment, the initiator of the polymer polyol is one or more of glycerol, trimethylolpropane, ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol, and the polymerization monomer is ε-caprolactone with a hydroxyl value of 28-140 mgKOH / g.

[0035] In a preferred embodiment, the aliphatic or aromatic chain extender is selected from one or more of 3,3'-dichloro-4,4'-methylenediaminodiphenylmethane (MOCA), diaminodimethylthiotoluene (DMTDA), diaminodimethylthioethylbenzene (DETDA), ethylene glycol (EG), 1,4-butanediol (BDO), 1,6-hexanediol (HDO), and trimethylolpropane (TMP). Further preferably, the aliphatic or aromatic chain extender is selected from one or more of ethylene glycol and 1,4-butanediol in a proportionate combination.

[0036] In a preferred embodiment, the composite foaming agent is deionized water and a low-boiling-point compound, wherein the deionized water is a chemical foaming agent and the low-boiling-point compound is a physical foaming agent, and the low-boiling-point compound includes cyclopentane, dichloromethane, and HCFC-141b. Further preferably, the composite foaming agent is a combination of deionized water and dichloromethane in a certain proportion.

[0037] In a preferred embodiment, the foam stabilizer is one or more of the silicone surfactants DC193, DC197 and DC5604.

[0038] In a preferred embodiment, the pore structure regulator is one or both of the organosilicon agents Niax L-6188 and AK-9901.

[0039] In a preferred embodiment, the composite catalyst is a mixed catalyst composed of a tertiary amine catalyst and an organometallic catalyst. Wherein, the tertiary amine catalyst is selected from one or more of triethylenediamine (TEDA), dimethylcyclohexylamine (DMCHA), pentamethyldiethylenetriamine (PMDETA), and tetramethylethylenediamine (TMED); and the organometallic catalyst is selected from one or more of dibutyltin dilaurate (DBTL), dibutyltin diacetate (DBTAC), stannous octoate, di(dodecylsulfide)dibutyltin, potassium acetate, and potassium oleate. Further preferably, the composite catalyst is a mixed catalyst composed of a tertiary amine catalyst triethylenediamine and an organometallic catalyst dibutyltin dilaurate.

[0040] In a preferred embodiment, the filler is one or more of tetrafluoroethylene, polyethylene wax powder and silicon dioxide.

[0041] In a preferred embodiment, the modified isocyanate mixture is a polyisocyanate modified with a polymer polyol, wherein the polyisocyanate is selected from one or more of diphenylmethane diisocyanate (MDI), liquefied modified diphenylmethane diisocyanate, toluene diisocyanate (TDI), and polyphenylmethane polyisocyanate (PAPI). Further preferably, the modified isocyanate mixture is diphenylmethane diisocyanate modified with a polymer polyol.

[0042] The following combination Figure 2 and 3 Next, the disconnecting device 5 of the crack and hole plugging tool 100 according to the present invention is introduced.

[0043] like Figure 2As shown, the disconnecting device 5 includes a hollow outer tube 52, and an upper connecting sleeve 51 and a lower joint 58 respectively connected to the upper end of the outer tube 52. The disconnecting device 5 is connected to the base pipe 2 ( Figure 1 ) to form a fixed connection, and is connected to other functional short sections (not shown) on the pipe string through a lower joint 58. A ball seat 56 is formed in the inner cavity of the lower joint 58, and a first waist-shaped hole 57 is formed in the outer cylinder 52 and extends axially through the outer wall thereof. Their functions will be described below.

[0044] An inner cylinder 55 is provided inside the outer cylinder 52, and its upper and lower ends are fixedly connected to the upper connecting sleeve 51 and the lower joint 58 respectively, so as to remain fixed relative to the outer cylinder 52. A piston cylinder 54 is provided between the outer cylinder 52 and the inner cylinder 55, and is configured to be able to slide in the outer cylinder 52 along the axial direction. Specifically, the radial outer surface of the piston cylinder 54 fits with the radial inner surface of the outer cylinder 52, so that the outer cylinder 52 can provide a radial outer guide for the sliding of the piston cylinder 54. At the same time, the radial inner surface of the piston cylinder 54 fits with the radial outer surface of the inner cylinder 55, so that the inner cylinder 55 can provide a radial inner guide for the sliding of the piston cylinder 54 and provide a supporting effect at the same time. However, in Figure 2 In the initial state shown, the piston cylinder 54 and the outer cylinder 52 are fixedly connected together by the shear pin 53.

[0045] According to the present invention, a support mechanism 60 is provided at the downstream end of the piston cylinder 54. The support mechanism 60 includes a support rod 62. The radially inner end of the support rod 60 is hinged to the outer wall of the inner cylinder 55 via a pivot pin 66. Furthermore, a second waist-shaped hole 68 is formed in the support rod 62, into which a sliding pin 64 connected to the downstream end of the piston cylinder 54 is inserted.

[0046] When the disconnecting device 5 is in the Figure 2 In the initial state shown, the piston cylinder 54 and the outer cylinder 52 are fixedly connected together by the shear pin 53, and the radially outer ends of the support rods 62 of the support mechanism 60 extend radially through the first waist-shaped holes 57 in the outer wall of the outer cylinder 52. Thus, the support rods 62 are arranged generally radially, providing stable and reliable support for the self-expanding plugging layer 4.

[0047] After the self-expanding plugging layer 4 has completed its self-expanding and is attached to the crack or hole where the plugging is required, the crack or hole plugging tool 100 can be retrieved. Figure 3 As shown, a ball is thrown into the seam hole plugging tool 100 so that a small ball (not shown) falls onto the ball seat 56 of the lower joint 58. In this case, pressure can be held in the pipe string.

[0048] When the pressure exceeds the shear stress of the shear pin 53, the shear pin 53 is sheared. At this time, the piston cylinder 54 will slide downward between the outer cylinder 52 and the inner cylinder 55 under the action of pressure. As the piston cylinder 54 moves downward, the sliding pin 64 connected to the downstream end of the piston cylinder 54 also moves in the first waist-shaped hole 68, thereby pushing the support rod 62 of the support mechanism 60 to pivot inward around the rotating pin 66. Therefore, the radial outer end of the support rod 62 gradually shrinks inward until it no longer extends outside the outer cylinder 52. In this case, the fracture plugging tool 100 can be lifted out of the wellbore by a lifting operation. It should be noted that at this time, the self-expanding plugging layer 4 will be separated from the fracture plugging tool 100, and it will still remain in the fracture hole that needs to be plugged, thereby producing a long-term plugging effect.

[0049] As will be readily understood, in a preferred embodiment, the support mechanism 60 includes a plurality of support rods 62, which are connected to the downstream end of the piston cylinder 54 at intervals along the circumferential direction. Furthermore, a plurality of first waist-shaped holes 57 are formed in the outer cylinder 52, extending through the outer wall of the outer cylinder 52 at intervals along the circumferential direction. Each support rod 62 extends through a corresponding first waist-shaped hole 57. Thus, the support mechanism 60 provides uniform and stable circumferential support for the self-expanding plugging layer 4.

[0050] The present invention also provides a method for plugging leaks in cracks and holes. Figures 4A to 4D To introduce.

[0051] First, if Figure 4A As shown, after a loss point 130 is generated in the formation 120 , the wellbore 110 is reamed using a conventional reaming tool 150 .

[0052] Then, if Figure 4B As shown, the fracture-hole plugging tool 100 according to the present invention is run into the leakage point 130 in the wellbore 110. Preferably, the length of the self-expanding plugging layer 4 of the fracture-hole plugging tool 100 should cover the entire leakage point 130.

[0053] Then, if Figure 4C As shown, the high temperature and high pressure conditions downhole trigger the self-expanding plugging layer 4 made of shape memory composite material in the fracture-cavity plugging tool 100 to start expanding, thereby plugging the cave leakage point 130.

[0054] After the expansion is completed, the ball is thrown into the pipe string to hold the pressure in the crack and hole plugging tool 100, thereby retracting the support rod. At this time, the crack and hole plugging tool 100 can be lifted out of the wellbore by lifting operation. In this case, if Figure 4D As shown, the self-expanding plugging layer 4 remains at the leakage point 130 in the wellbore 110, thereby providing a long-term plugging effect.

[0055] The crack-hole plugging tool according to the present invention can achieve efficient plugging, has a simple structure, and is safe and reliable. At the same time, after completing the plugging operation, the crack-hole plugging tool according to the present invention can be easily recovered from the wellbore through simple operation.

[0056] When the fracture-hole plugging tool according to the present invention is used in an open hole well, the tool's self-expanding plugging layer not only seals leaks but also supports the wellbore wall, maintaining its stability and preventing collapse. Furthermore, the tool's self-expanding plugging layer expands to fit snugly at the leak point, ensuring the original wellbore dimensions remain intact, allowing subsequent drilling or other operations to continue after the leaking layer is sealed.

[0057] In addition, the construction process of the fracture hole plugging method according to the present invention is simple, does not require large-scale ground equipment, is conducive to promotion and application in various well types, and avoids the consumption of a large amount of expensive plugging materials and processing time.

[0058] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A crack and hole sealing tool (100), characterized in that: It comprises a base pipe (2), a disconnecting tool (5) connected to the downstream of the base pipe (2), and a self-expanding plugging layer (4) installed on the base pipe (2). The self-expanding plugging layer (4) is configured to be able to self-expand under downhole conditions so as to plug downhole leakage points; The disconnecting tool (5) is configured to have a first state in which it is initially radially extended to support the self-expanding plugging layer (4), and a second state in which it is radially retracted after the self-expanding plugging layer (4) self-expands; The disconnecting tool (5) comprises a piston cylinder (54) capable of axial movement within the disconnecting tool (5), and a support mechanism (60) connected to the piston cylinder (54). Wherein, in the first state, the support mechanism (60) extends radially to support the self-expanding plugging layer (4). In the second state, the support mechanism (60) is capable of radially retracting in response to axial movement of the piston cylinder (54); The disconnecting tool (5) comprises an outer cylinder (52) and an inner cylinder (55), and the piston cylinder (54) is arranged between the outer cylinder (52) and the inner cylinder (55). Wherein, in the first state, the piston cylinder (54) is fixed inside the outer cylinder (52) by a shear pin (53). In the second state, the shear pin (53) is sheared, so that the piston cylinder (54) can move axially between the outer cylinder (52) and the inner cylinder (55); The support mechanism (60) comprises a support rod (62), the radial inner end of the support rod (62) being hinged to the outer wall of the inner cylinder (55), and the radial outer end of the support rod (62) being able to pass through the first waist-shaped through hole (57) on the outer cylinder (52) and to radially extend and retract; A second waist-shaped hole (68) is formed on the support rod (60), and a sliding pin (64) is provided at the downstream end of the piston cylinder (54) and is inserted into the second waist-shaped hole (68); The disconnecting tool (5) comprises an upper connecting sleeve (51) for connecting to the base pipe (2), and a lower joint (58) in which a ball seat (56) is formed. The disconnecting tool (5) is capable of changing from a first state to a second state in response to a pressure buildup caused by pitching a ball onto the ball seat (56); The crack and hole plugging tool (100) further comprises an upper joint (1), and the self-expanding plugging layer (4) is axially located between the upper joint (1) and the disconnecting tool (5).

2. The crack and hole sealing tool according to claim 1, characterized in that: The outer cylinder (52) and the inner cylinder (55) are fixedly connected to the upper connecting sleeve (51) and the lower joint (58) at the upstream end and the downstream end, respectively.

3. The crack and hole sealing tool according to claim 2, characterized in that: The self-expanding leak-proof layer (4) is a shape-memory rigid polyurethane foam.

4. The crack and hole sealing tool according to claim 2, characterized in that: The crack and hole plugging tool (100) further comprises an upper joint (1), and the self-expanding plugging layer (4) is axially located between the upper joint (1) and the disconnecting tool (5).

5. A method for plugging a crack hole, comprising the following steps: The fracture-hole plugging tool (100) according to any one of claims 1 to 4 is lowered into the underground leakage point, wherein: The support rod (62) of the support mechanism (60) of the crack and hole plugging tool (100) extends radially to support the self-expanding plugging layer (4) of the crack and hole plugging tool (100); Prompting the self-expanding plugging layer (4) to expand and plug the underground leakage point; Throwing a ball toward the crack-hole plugging tool (100) so that the ball sits on the ball seat (56) in the lower joint (58) of the crack-hole plugging tool (100); By holding down pressure to shear off the shear pin (53) between the outer cylinder (52) and the piston cylinder (54) of the crack hole plugging tool (100), the piston cylinder (54) is caused to move axially downstream, thereby causing the support rod (62) to be radially retracted; The fracture and hole plugging tool (100) is lifted out of the wellbore.

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