A sleeve milling device

Abstract

The application belongs to the technical field of oilfield downhole operation, and particularly relates to a casing milling device. The casing milling device provided by the application comprises a first casing, a second casing, a cylinder, a casing milling pipe, a casing milling shoe, a sealing unit, a sealing-off unit and a liquid inlet unit. The casing milling device has a switchable first state and a second state. When the casing milling pipe is in the first state, the lower part of the casing milling pipe is located in the cylinder, the sealing-off unit seals the gap between the lower part of the casing milling pipe and the inner wall of the cylinder, and the sealing unit, the sealing-off unit, the casing milling pipe and the inner wall of the cylinder form a liquid inlet cavity. When the casing milling device is in the second state, the lower part of the casing milling pipe is located in a cement cavity, the sealing-off unit seals the gap between the lower part of the casing milling pipe and the inner wall of the first casing, and the sealing unit, the sealing-off unit, the casing milling pipe, the inner wall of the cylinder and the inner wall of the first casing form the liquid inlet cavity. One end of a flow channel is in communication with the liquid inlet cavity, and the other end is in communication with a jet hole.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oilfield downhole operation, and particularly relates to a casing milling device. BACKGROUND

[0002] Casing milling operation is one of the processes frequently applied in oilfield downhole operation, which is a process method for removing sand, cement, calcium carbonate crystals and the like between drilling tools and casings, casings and casings, the main tools of which are casing milling shoes and casing milling pipes. The construction process of casing milling operation is to connect the casing milling shoe to the casing milling pipe through threads or welding, then connect the casing milling pipe to the drilling tool, and provide rotating power by the rotary table or power swivel for construction.

[0003] The casing replacement technology is a casing damage well repair process, which is used for casing deformation, breakage, rupture and loss, uses the casing milling process to damage the annular cement ring, then takes out the damaged casing, and then lowers a new casing to complete the casing damage well repair. The repaired index is the same as that of a new well, can meet the requirements of all subsequent measures, and is the most complete casing damage well repair method. Before taking out the casing, the cement ring in the annulus between the two casings is first removed by casing milling operation, and then the next step is performed. However, the conventional casing milling process has low efficiency and long casing milling time, and long-time casing milling operation may cause damage to the casing. SUMMARY

[0004] To solve the technical problems of low efficiency and long casing milling time of the current casing milling process, and long-time casing milling operation may cause damage to the casing, the application provides a casing milling device.

[0005] The application provides a casing milling device, which comprises:

[0006] A barrel is arranged at the wellhead of the oil well, the barrel is connected with the first casing, and the inside of the barrel is communicated with the cement cavity; wherein the first casing is arranged in the oil well, the second casing is arranged in the first casing at intervals, and the cement ring is formed by the gap between the first casing and the second casing;

[0007] A casing milling pipe is movably arranged in the barrel and can be extended into the cement cavity from the barrel;

[0008] A casing milling shoe is arranged at the lower part of the casing milling pipe in communication, and the end face of the casing milling shoe is provided with a plurality of injection holes;

[0009] A sealing unit is arranged for sealing the gap between the upper part of the casing milling pipe and the inner wall of the barrel;

[0010] A sealing unit is used to seal the gap between the lower part of the milling tube and the inner wall of the cylinder or the inner wall of the first sleeve. The sealing unit, the sealing unit, the milling tube and the inner wall of the cylinder form a liquid inlet cavity, or the sealing unit, the sealing unit, the milling tube, the inner wall of the cylinder and the inner wall of the first sleeve form the liquid inlet cavity. The sealing unit has a flow channel, and the cross-section of the flow channel gradually narrows from top to bottom.

[0011] The liquid inlet unit is disposed between the sealing unit and the sealing unit and is connected to the liquid inlet chamber to introduce circulating liquid into the flow channel and then spray it out through the injection hole to form a high-speed water flow to break the cement ring in the cement chamber.

[0012] In some embodiments, the milling shoe includes a milling shoe body and a plurality of alloy blocks, the plurality of alloy blocks being circumferentially spaced along the end face of the milling shoe body, and the injection hole being disposed on the end face of the milling shoe body and located between two adjacent alloy blocks.

[0013] In some embodiments, the milling shoe body has a liquid channel inside, one end of which is connected to the flow channel and the other end is connected to the injection hole, and the lower part of the liquid channel is inclined towards the edge of the milling shoe body for convenience.

[0014] In some embodiments, the sealing unit includes a rubber sleeve and an upper pressure cap. The rubber sleeve is disposed in the gap between the upper part of the milling tube and the inner wall of the cylinder. The upper pressure cap is disposed on the top of the main body and sleeved in the main body. The milling tube passes through the upper pressure cap, and the upper pressure cap is pressed against the rubber sleeve.

[0015] In some embodiments, the rubber tube includes a rubber tube body and a rubber tube seat, the rubber tube seat is supported on the rubber tube body and disposed near the inner wall of the tube, and the rubber tube body is disposed between the milling sleeve and the rubber tube seat.

[0016] In some embodiments, the sealing unit further includes a sealing ring disposed between the rubber sleeve and the inner wall of the sleeve.

[0017] In some embodiments, the device further includes a bearing disposed between the milling sleeve and the inner wall of the cylinder.

[0018] In some embodiments, the sealing unit is connected to the milling sleeve, with one side of the sealing unit forming the flow channel between it and the lower part of the milling sleeve, and the other side abutting against the inner wall of the cylinder or the inner wall of the surface oil pipe.

[0019] In some embodiments, the packoff unit is a cup packoff, and a cup of the packoff unit abuts against the inner wall of the barrel or the inner wall of the surface tubing.

[0020] In some embodiments, the barrel comprises, from top to bottom, a housing, a connecting sleeve and a casing collar, the sealing unit is arranged in the housing, and the casing collar is connected with the first casing.

[0021] According to the casing milling device provided by one or more embodiments of the present application, since the sealing unit seals the gap between the upper part of the casing milling pipe and the inner wall of the barrel, i.e., the liquid inlet cavity is not in communication with the atmosphere, when the circulating liquid is introduced into the liquid inlet cavity by the liquid inlet unit, the circulating liquid will enter the flow channel. Since the cross section of the flow channel narrows from top to bottom, the pressure of the liquid inlet cavity will increase during the circulating liquid flowing through the flow channel. Under the action of the pressure, the circulating liquid will be sprayed out at high speed through the spray hole, forming a high-speed water flow. Therefore, the high-speed water flow and the casing milling shoe jointly act to break the cement sheath, which can improve the breaking efficiency of the cement sheath, change the problem of low efficiency of the traditional casing milling which only relies on the grinding of the casing milling shoe, and to some extent, avoid the situation of damage to the casing caused by long-time casing milling operation. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A structural schematic view when the casing milling device is in a first state is shown.

[0023] Figure 2 A partial enlarged view in Figure 1 is shown.

[0024] Figure 3 A structural schematic view when the casing milling device is in a second state is shown.

[0025] Figure 4 A structural schematic view of the end surface of the casing milling shoe in Figure 1 is shown.

[0026] BRIEF DESCRIPTION OF DRAWINGS

[0027] 100 - casing milling device, 110 - first casing, 120 - second casing, 130 - barrel, 131 - liquid inlet cavity, 132 - housing, 133 - connecting sleeve, 134 - casing collar, 135 - stepped structure, 140 - casing milling pipe, 150 - casing milling shoe, 151 - casing milling shoe body, 152 - alloy block, 153 - spray hole, 154 - liquid passage, 160 - sealing unit, 161 - rubber sleeve, 1611 - rubber sleeve body, 1612 - rubber sleeve seat, 1613 - rubber sleeve gland, 162 - upper gland, 163 - sealing ring, 170 - packoff unit, 171 - flow channel, 180 - liquid inlet unit, 190 - bearing, 191 - first bearing, 192 - second bearing. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to which the present application pertains to more clearly understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0029] In conjunction with Figures 1-3 The sleeve milling device 100 provided by the embodiments of the present application can form a high-speed water flow and a sleeve milling shoe 150 to jointly break the cement ring during sleeve milling operation, so as to improve the breaking efficiency of the cement ring, reduce the sleeve milling time, and to a certain extent, avoid long-time sleeve milling operation to damage the casing.

[0030] The sleeve milling device 100 provided by the embodiments of the present application includes a first casing 110, a second casing 120, a barrel 130, a sleeve milling pipe 140, a sleeve milling shoe 150, a sealing unit 160, a sealing-off unit 170, and a liquid inlet unit 180. The first casing 110 is arranged in an oil well, the second casing 120 is arranged in the first casing 110 at intervals, and a cement cavity is formed between the first casing 110 and the second casing 120, and the cement cavity has a cement ring; the barrel 130 is arranged at the wellhead of the oil well, the barrel 130 is connected with the first casing 110, and the inside of the barrel 130 is in communication with the cement cavity; the sleeve milling pipe 140 is movably arranged in the barrel 130 and can be extended into the cement cavity from the barrel 130; the sleeve milling shoe 150 is arranged at the lower part of the sleeve milling pipe 140 in communication, and the end face of the sleeve milling shoe 150 is provided with a plurality of jet holes 153; the sealing unit 160 is used to seal the gap between the upper part of the sleeve milling pipe 140 and the inner wall of the barrel 130; the sealing-off unit 170 is used to seal the gap between the lower part of the sleeve milling pipe 140 and the inner wall of the barrel 130 or the inner wall of the first casing 110; the sealing unit 160, the sealing-off unit 170, the sleeve milling pipe 140, and the inner wall of the barrel 130 form a liquid inlet cavity 131, or the sealing unit 160, the sealing-off unit 170, the sleeve milling pipe 140, the inner wall of the barrel 130, and the inner wall of the first casing 110 form the liquid inlet cavity 131; the sealing-off unit 170 has a flow channel 171, and the cross section of the flow channel 171 narrows from top to bottom.

[0031] The sleeve milling device 100 has a switchable first state and second state, when the sleeve milling pipe 140 is in the first state, the lower part of the sleeve milling pipe 140 is located in the barrel 130, the sealing unit 160, the sealing unit 170, the sleeve milling pipe 140 and the inner wall of the barrel 130 form a liquid inlet cavity 131, when the sleeve milling device 100 is in the second state, the lower part of the sleeve milling pipe 140 is located in the cement cavity, the sealing unit 160, the sealing unit 170, the sleeve milling pipe 140, the inner wall of the barrel 130 and the inner wall of the first casing 110 form a liquid inlet cavity 131, one end of the flow channel 171 is communicated with the liquid inlet cavity 131, and the other end is communicated with the jet hole 153, the liquid inlet unit 180 is arranged between the sealing unit 160 and the sealing unit 170 and communicated with the liquid inlet cavity 131, so that the circulating liquid is introduced into the flow channel 171 and then sprayed out of the jet hole 153 to form a high-speed water flow to break the cement ring.

[0032] In the process of drilling, when the drill bit drills to a certain depth, a steel casing is put into the well, and then cement is injected into the annular space between the casing and the borehole, and after the cement solidifies, the well wall can be prevented from collapsing, and then a smaller drill bit is replaced to continue drilling down into the casing, when drilling to a certain depth and the well wall is unstable, the drill string is lifted, a smaller casing is put into the original casing and extended downward, and then cement is injected between the casing and the borehole, and so on. That is, almost all oil wells will have two or more casings, the number of casings can be determined according to the depth and geological conditions, the casings from large to small are surface casing, technical casing, oil layer casing, tail pipe and the like, the first casing 110 and the second casing 120 in the embodiment can be any two casings arranged adjacently, of course, the size of the second casing 120 is smaller than that of the first casing 110.

[0033] The barrel 130 is arranged on the ground and corresponds to the wellhead, one end of the sleeve milling pipe 140 is arranged outside the barrel 130 (not shown in the figure) and connected with the drilling tool, and the other end is arranged in the barrel 130 and can be extended downward into the cement cavity, that is, when the sleeve milling pipe 140 is located in the cement cavity, the sleeve milling pipe 140 is arranged between the first casing 110 and the second casing 120, of course, as the oil well is drilled deeper, the sleeve milling pipe 140 can be continuously extended downward to adapt to the depth of the oil well. The sleeve milling teeth are arranged on the end face of the sleeve milling shoe 150, the sleeve milling pipe 140 can be provided with rotary power by a power swivel or a rotary table to drive the sleeve milling shoe 150 to rotate, so that the sleeve milling teeth on the sleeve milling shoe 150 can break the cement ring by rotating.

[0034] The sealing unit 160 is used to seal the gap between the upper part of the milling sleeve 140 and the inner wall of the cylinder 130, and the sealing unit 170 is used to seal the gap between the lower part of the milling sleeve 140 and the inner wall of the cylinder 130 or the inner wall of the first sleeve 110. It should be noted that the "upper part of the milling sleeve 140" here refers to the upper part of the milling sleeve 140 located in the cylinder 130, and the "lower part of the milling sleeve 140" refers to the part of the milling sleeve 140 close to the milling shoe 150.

[0035] When milling begins on a well where cement has risen to the surface, the milling tube 140 is in its first state, with its lower part located inside the cylinder 130. The packer unit 170 seals the gap between the lower part of the milling tube 140 and the inner wall of the cylinder 130. The sealing unit 160, packer unit 170, milling tube 140, and inner wall of the cylinder 130 form an inlet chamber 131. After the inlet unit 180 introduces circulating fluid into the inlet chamber 131, the circulating fluid enters the flow channel 171. Because the cross-section of the flow channel 171 gradually narrows from top to bottom, the pressure in the inlet chamber 131 increases as the circulating fluid flows through it. Under this pressure, the circulating fluid is ejected at high speed through the injection hole 153, forming a high-speed water flow that can break the cement sheath that has risen to the surface. As the cement sheath is broken, the lower part of the milling tube 140 gradually extends from the cylinder 130 into the water... In the mud chamber, the milling tube 140 is in the second state. The sealing unit 170 seals the gap between the lower part of the milling tube 140 and the inner wall of the first casing 110. The sealing unit 160, the sealing unit 170, the milling tube 140, the inner wall of the cylinder 130 and the inner wall of the first casing 110 form the inlet chamber 131. Of course, the inner wall of the first casing 110 is connected to the lower part of the inner wall of the cylinder 130. Similarly, after the inlet unit 180 introduces the circulating fluid into the inlet chamber 131, the circulating fluid will enter the flow channel 171. Since the cross-section of the flow channel 171 gradually narrows from top to bottom, the pressure of the inlet chamber 131 will increase during the flow of the circulating fluid through the flow channel 171. Under the action of pressure, the circulating fluid will be ejected at high speed through the injection hole 153 to form a high-speed water flow, which can break the cement sheath downhole. As the milling depth increases, the extension length of the milling tube 140 also becomes longer. Based on the existing method of using the milling shoe 150 to break the cement ring, a high-speed water flow is added to further break the cement ring. This allows the high-speed water flow and the milling shoe 150 to work together to break the cement ring, thereby improving the breaking efficiency of the cement ring and avoiding damage to the casing caused by prolonged milling operations.

[0036] In some embodiments, the inlet unit 180 is used to provide circulating fluid that needs to be returned to the ground after the cement ring is broken. The inlet unit 180 includes a bypass and a pumping device, which pumps the circulating fluid from the bypass into the inlet chamber 131.

[0037] It should be noted that the broken cement is returned out through the inside of the circulating fluid through the underreamer pipe 140.

[0038] It is worth mentioning that the sealing unit 160 is arranged to not only isolate the liquid inlet cavity 131 from the atmosphere, form a high-pressure liquid inlet cavity 131, so that the circulating fluid can be sprayed out at high speed through the jet hole under the action of pressure when passing through the flow channel 171 with a narrowing cross section, but also to a certain extent, avoid the circulating fluid from flowing out from the upper passage between the underreamer pipe 140 and the cylinder 130, and ensure that the circulating fluid and the broken cement are returned to the ground through the underreamer pipe 140.

[0039] In some embodiments, in combination with Figures 3-4 The underreamer shoe 150 includes an underreamer shoe 150 body and a plurality of alloy blocks 152, the plurality of alloy blocks 152 are arranged at intervals along the circumference of the end face of the underreamer shoe 150 body, and the jet hole 153 is arranged on the end face of the underreamer shoe 150 body and located between the two adjacent alloy blocks 152.

[0040] The alloy block 152 is a hard alloy block 152 to enhance the wear resistance of the underreamer shoe 150, and specifically, the alloy block 152 can be cobalt-containing tungsten carbide. The recess is formed between the two adjacent alloy blocks 152, and the jet hole 153 is arranged in the recess. Since the jet hole 153 is located between the two adjacent alloy blocks 152, the arrangement of the jet hole 153 does not interfere with the alloy block 152. The number of jet holes 153 can be set according to actual needs, that is, a jet hole 153 can be arranged in each recess, or a jet hole 153 can be arranged at an interval of one recess, and no limitation is made on this.

[0041] It is worth mentioning that the plurality of jet holes 153 can be arranged at equal intervals along the end face of the underreamer shoe 150 body, so that the annular cement ring can be uniformly sprayed, and the hydraulic mud breaking efficiency and the cleaning degree of the underreaming surface can be improved.

[0042] In some embodiments, the underreamer shoe 150 body is provided with a liquid passage 154, one end of the liquid passage 154 is in communication with the flow channel 171, the other end is in communication with the jet hole 153, and the lower part of the liquid passage 154 is conveniently inclined to the edge of the underreamer shoe 150 body.

[0043] Since the liquid passage 154 is arranged obliquely, the water flow sprayed out of the jet hole 153 is also obliquely sprayed out. The oblique design of the liquid passage 154 can cooperate with the alloy arrangement of the underreamer shoe 150 to improve the smoothness of the rotary milling of the underreamer shoe 150, and is more conducive to carrying the cement debris and cooling the underreamer shoe 150.

[0044] In some embodiments, the sealing unit 160 comprises a rubber sleeve 161 and an upper cover 162, the rubber sleeve 161 is arranged in the gap between the upper part of the sleeve mill pipe 140 and the inner wall of the barrel 130, and the upper cover 162 is arranged on the top of the main body and is sleeved in the main body, the sleeve mill pipe 140 is arranged in the upper cover 162, and the upper cover 162 is arranged in extrusion with the rubber sleeve 161.

[0045] The rubber sleeve 161 is made of flexible material, and is arranged in the gap between the upper part of the sleeve mill pipe 140 and the inner wall of the barrel 130. At the same time, the upper cover 162 extrudes the rubber sleeve 161, so that the rubber sleeve 161 is deformed and is arranged in interference in the gap, so as to achieve better sealing effect.

[0046] The lower end of the upper cover 162 is provided with a thread to be screwed with the barrel 130. After the upper cover 162 is fastened to the barrel 130 by screwing, the upper cover 162 will extrude the rubber sleeve 161.

[0047] Specifically, the rubber sleeve 161 comprises a rubber sleeve main body 1611 and a rubber sleeve seat 1612, the rubber sleeve seat 1612 is arranged on the rubber sleeve main body 1611, and the rubber sleeve seat 1612 is arranged close to the inner wall of the barrel 130. The rubber sleeve main body 1611 is arranged between the sleeve mill pipe 140 and the rubber sleeve seat 1612.

[0048] The rubber sleeve seat 1612 supports the rubber sleeve main body 1611 and prevents the rubber sleeve main body 1611 from being damaged under certain pressure. The contact surface between the rubber sleeve seat 1612 and the rubber sleeve main body 1611 can be inclined, so that the rubber sleeve seat 1612 and the rubber sleeve main body 1611 are more closely attached, so as to ensure better sealing effect.

[0049] In some embodiments, the sealing unit 160 further comprises a sealing ring 163, which is arranged between the rubber sleeve 161 and the inner wall of the barrel 130.

[0050] The sealing ring 163 is arranged between the rubber sleeve 161 and the inner wall of the barrel 130, so as to further improve the sealing effect between the sleeve mill pipe 140 and the inner wall of the barrel 130. Specifically, the sealing ring 163 is arranged between the rubber sleeve seat 1612 and the inner wall of the barrel 130.

[0051] In some embodiments, the device further comprises a bearing 190 arranged between the sleeve mill pipe 140 and the inner wall of the barrel 130.

[0052] As described above, the sleeve mill pipe 140 will rotate under the action of the power faucet or the rotary table to drive the sleeve mill shoe 150 to rotate. Therefore, in order to reduce the friction of the sleeve mill pipe 140 during rotation and to a certain extent avoid damage to the sleeve mill pipe 140, the bearing 190 is arranged between the sleeve mill pipe 140 and the inner wall of the barrel 130.

[0053] Specifically, the bearing 190 can be a thrust ball bearing 190. Two bearings 190 can be provided, namely a first bearing 191 and a second bearing 192. The first bearing 191 is arranged between the upper gland 162 and the rubber sleeve 161, i.e. the upper gland 162 exerts pressure on the rubber sleeve 161 through the bearing 190. The second bearing 192 is arranged below the rubber sleeve 161, i.e. the rubber sleeve 161 is arranged between the first bearing 191 and the second bearing 192. The inner wall of the barrel 130 is provided with a stepped structure 135, and the second bearing 192 is clamped on the stepped structure 135. When the upper gland 162 is screwed onto the barrel 130, pressure is applied to the first bearing 191, and the rubber sleeve 161 is pressed under the support of the second bearing 192, so as to be arranged in the gap with an interference, thereby achieving a better sealing effect.

[0054] Of course, the bearing 190 can also be provided in multiple, which is not limited.

[0055] In addition, a rubber sleeve gland 1613 can be arranged between the bearing 190 and the rubber sleeve 161, which mainly serves to protect the rubber sleeve 161 from damage caused by the rotation of the bearing 190 and the tightening of the upper gland 162.

[0056] In some embodiments, the sealing unit 170 is connected to the reamer shoe 150, and a flow channel 171 is formed between one side of the sealing unit 170 and the lower part of the reamer pipe 140. The other side of the sealing unit 170 abuts against the inner wall of the barrel 130 or the inner wall of the surface tubing.

[0057] Specifically, the sealing unit 170 can be a cup seal packer. The cup of the sealing unit 170 abuts against the inner wall of the barrel 130 or the inner wall of the surface tubing. The cup seal packer and the reamer shoe 150 can be connected together by a steel ball. During the rotation of the reamer shoe 150, the cup seal packer remains in a stationary state. When the circulating fluid enters the flow channel 171, the flow channel 171 narrows, the pressure in the liquid inlet chamber 131 increases, and under the action of the pressure, the cup of the cup seal packer tightly abuts against the inner wall of the sleeve, so as to achieve sealing.

[0058] In some embodiments, the barrel 130 includes an outer shell 132, a connecting sleeve 133 and a sleeve coupling 134 connected in sequence from top to bottom. The sealing unit 160 is arranged in the outer shell 132. The connecting sleeve 133 is used to connect the outer shell 132 and the sleeve coupling 134. The sleeve coupling 134 is connected to the first sleeve 110.

[0059] In some embodiments, sand can be added to the circulating fluid. When the sand content is 5%, the flow rate at the jet hole can reach 80-100 m / S, the breaking distance is greater than 20 mm, and the auxiliary breaking effect is obvious.

[0060] Next, the use method of the reamer device 100 will be described:

[0061] The cylinder 130 is assembled with the reaming pipe 140 and the reamer shoe 150 on the ground, the bottom of the cylinder 130 is welded with the first casing pipe 110 outside the cement sheath of the construction well, and pressure test is carried out at 15 MPa; after the reamer shoe 150 reaches the cement surface, reaming construction is prepared, circulating fluid is pumped from the bypass pump by the cement truck, the rubber bowl packer is tightly attached to the inner wall of the first casing pipe 110 under the action of pressure to form a closed space, at this time, circulating fluid enters the flow channel 171 from the closed space, because the cross section of the flow channel 171 changes from wide to narrow, when the circulating fluid flows through the narrower part, the pressure of the liquid inlet cavity 131 increases, under the action of pressure, the circulating fluid entering the liquid channel 154 is sprayed at high speed from the jet hole 153 on the end surface of the reamer shoe 150, the rotating power swivel is operated to start reaming the cement sheath, so that the high-speed water flow realizes double-acting crushing of the cement sheath together with the reamer shoe 150. The rotating speed can be adjusted according to the actual situation on site, and the circulating pump displacement is gradually adjusted to increase the pressure of the jet hole 153, and the highest pressure is controlled within 15 MPa. After one reaming pipe 140 is reamed, another reaming pipe 140 is connected to continue reaming, and the above operation is repeated until the reaming depth is reached.

[0062] The reaming device 100 provided by the embodiment of the application seals the gap between the upper part of the reaming pipe 140 and the inner wall of the cylinder 130 through the sealing unit 160, that is, the liquid inlet cavity 131 is not in communication with the atmosphere, when the circulating fluid is introduced into the liquid inlet cavity 131 by the liquid inlet unit 180, the circulating fluid will enter the flow channel 171, because the cross section of the flow channel 171 narrows from top to bottom, the pressure of the liquid inlet cavity 131 will increase in the process of circulating fluid flowing through the flow channel 171, under the action of pressure, the circulating fluid will be sprayed at high speed through the jet hole 153 to form a high-speed water flow, so that the cement sheath can be broken, that is, the high-speed water flow and the reamer shoe 150 jointly act to crush the cement sheath, and the crushing efficiency of the cement sheath can be improved, and to some extent, damage to the casing caused by long-time reaming operation is avoided.

[0063] In the present application, unless specifically defined and limited otherwise, "on" or "under" of a first feature to a second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, "on", "above" and "upper" of a first feature to a second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. "Below", "under" and "lower" of a first feature to a second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0064] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0065] In the present application, unless otherwise expressly specified and limited, the terms "connection", "fixation" and the like should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0066] In addition, in the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise expressly specified and limited.

[0067] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A back reaming device characterized by, The device comprises: a barrel arranged at the wellhead of an oil well, the barrel being connected with a first casing pipe, and the inside of the barrel being communicated with a cement cavity; wherein the first casing pipe is arranged in the oil well, a second casing pipe is arranged in the first casing pipe at intervals, and the cement cavity is formed by the gap between the first casing pipe and the second casing pipe; a casing pipe which is movably arranged in the barrel and can be extended into the cement cavity from the barrel; a casing shoe which is arranged at the lower part of the casing pipe and has a plurality of jet holes arranged on the end face of the casing shoe; a sealing unit for sealing the gap between the upper part of the casing pipe and the inner wall of the barrel, the sealing unit comprising a rubber tube and an upper gland, the rubber tube being arranged in the gap between the upper part of the casing pipe and the inner wall of the barrel, and the upper gland being arranged at the top of the barrel and sleeved in the barrel, the casing pipe being arranged in the upper gland, and the upper gland being pressed against the rubber tube; a pack-off unit for sealing the gap between the lower part of the casing pipe and the inner wall of the barrel or the inner wall of the first casing pipe, the sealing unit and the pack-off unit, the casing pipe and the inner wall of the barrel forming a liquid inlet cavity, or the sealing unit, the pack-off unit, the casing pipe, the inner wall of the barrel and the inner wall of the first casing pipe forming the liquid inlet cavity, the pack-off unit having a flow channel, and the cross section of the flow channel being gradually narrowed from top to bottom; a liquid inlet unit arranged between the sealing unit and the pack-off unit and communicated with the liquid inlet cavity, so as to pass the circulating liquid into the flow channel and then out of the jet holes to form high-speed water flow for breaking the cement ring in the cement cavity.

2. The sleeve-milling device of claim 1, wherein, The casing shoe comprises a casing shoe body and a plurality of alloy blocks, the alloy blocks being arranged at intervals along the circumferential direction of the end face of the casing shoe body, and the jet holes being arranged on the end face of the casing shoe body and located between two adjacent alloy blocks.

3. The sleeve-milling device of claim 1, wherein, The casing shoe body is internally provided with a liquid passage, one end of the liquid passage being communicated with the flow channel, the other end being communicated with the jet holes, and the lower part of the liquid passage being inclined towards the edge of the casing shoe body.

4. The sleeve-milling device of claim 1, wherein, The rubber tube comprises a rubber tube body and a rubber tube seat, the rubber tube seat being supported on the rubber tube body, and the rubber tube seat being arranged close to the inner wall of the barrel, and the rubber tube body being arranged between the casing pipe and the rubber tube seat.

5. The sleeve-milling device of claim 1, wherein, The sealing unit further comprises a sealing ring, the sealing ring being arranged between the rubber tube and the inner wall of the barrel.

6. The sleeve-milling device of any one of claims 1-3, wherein, The device further comprises a bearing arranged between the casing pipe and the inner wall of the barrel.

7. The sleeve-milling device of any one of claims 1-3, wherein, The pack-off unit is connected with the casing shoe, one side of the pack-off unit being communicated with the lower part of the casing pipe to form the flow channel, and the other side of the pack-off unit being abutted against the inner wall of the barrel or the inner wall of the surface oil pipe.

8. The sleeve-milling device of claim 7, wherein, The pack-off unit is a leather cup packer, and the leather cup of the pack-off unit is abutted against the inner wall of the barrel or the inner wall of the surface oil pipe.

9. The sleeve-milling device of claim 1, wherein, The barrel comprises an outer shell, a connecting sleeve and a casing pipe nipple which are connected in sequence from top to bottom, the sealing unit is arranged in the outer shell, and the casing pipe nipple is connected with the first casing pipe.

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