A packer-type staged cementing tool

Abstract

The present invention discloses a packer-type staged cement injector, which relates to the technical field of oil extraction. It includes a closed casing member, a floating foot, a centralizing and straightening assembly, a separating assembly, an external casing packer, and an operating rubber plug mechanism. The closed casing member includes a plurality of casings. A floating foot is provided at the lower end of the closed casing member. A centralizing and straightening assembly is provided outside the casings. A separating assembly is provided between the casings. An external casing packer is provided outside the casings. An operating rubber plug mechanism is provided inside the casings. In the present invention, the mounting rings at both ends of the centralizing and straightening assembly are fixed to the outside of the casings. The telescopic plate in the centralizing and straightening assembly and the telescopic movement inside the square casing are used to offset the displacement between the two mounting rings caused by elastic deformation, ensuring that the centralizing and straightening assembly is located outside the casings, increasing the stability and position fixation of the centralizer on the casings. After detecting the inside of the oil well, presetting the installation of the centralizer on the casings can play a greater role.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and particularly to a packer-type staged cement injector. Background Art

[0002] With the increasing frequency of oil exploration and production activities, drilling technology has been continuously developed. Before drilling into the oil layer, effective cementing measures are required. The continuous increase in drilling depth and the frequent occurrence of complex geological conditions have put forward higher requirements for cementing technology. The purpose is to ensure that the annular space between the casing and the wellbore is effectively sealed, thereby isolating different formation fluids (such as oil, gas, water), and providing stable structural support for subsequent production activities. By forming a circular cement seal ring in the wellbore in an injection manner, the corrosion effect of oil, gas, etc. (such as hydrogen sulfide) in the soil layer on the casing is reduced.

[0003] However, when the current staged cement injector is lowered by sleeving an elastic or rigid centralizer outside the sealed casing, the centrality of the casing is maintained by the centralizer. During the cementing operation of oil wells at greater depths, an elastic centralizer is often required to centralize the closed sleeve. The existing elastic centralizer uses a leaf spring centralizer. When it penetrates into the interior of the oil well, due to the deformation of the leaf spring, the rings at both ends of the centralizer will expand and contract outside the casing. Due to the movement between the casing and the rings at both ends of the centralizer, the position of the centralizer will shift, easily changing the position of the centralizer outside the sleeve, affecting the centrality of the casing and the grouting operation of the cement slurry during the cementing operation.

[0004] In the existing technology, there is a lack of equipment and technology that can well solve the above problems. Summary of the Invention

[0005] The present invention provides a packer-type staged cement injector to solve the defect that the elastic centralizer of the cement injector is prone to move and misalign during the lowering in the deep well section in the prior art.

[0006] The present invention provides a packer-type staged cement injector, comprising: a closed casing member, which is composed of several casings uniformly distributed along the axial direction, there are gaps between the casings, the casings are connected by connecting sleeves arranged therebetween, the outer side wall of the connecting sleeve is provided with several uniformly distributed diversion holes, and uniformly distributed limit retaining rings are arranged outside each casing; a floating shoe, which is arranged at the bottom end outside the closed casing member, a check valve mechanism is arranged inside the floating shoe, and a float collar is arranged on the lower side outside the closed casing member; a centralizing and straightening assembly, which is arranged on each casing, and the centralizing and straightening assembly is located between two limit retaining rings of the same casing; a separating assembly, which is arranged at the gap between the casings; an outer casing packer, which is arranged outside the casing; an operating rubber plug mechanism, which is arranged inside the casing.

[0007] Optionally, the check valve mechanism includes a ball seat arranged inside the floating shoe, a circular hole communicating up and down is provided at the center of the ball seat, several flow-through bottom holes distributed around the central circular hole are provided at the upper edge of the ball seat, a valve ball used in cooperation with the circular hole at the center is arranged at the upper end of the ball seat, the upper end inside the floating shoe is a necking for cooperating with the valve ball, the inside of the floating shoe and the inside of the casing are connected through, and the valve ball can move up and down between the ball seat and the necking.

[0008] Optionally, the centralizing and straightening assembly includes an installation ring, the installation ring is arranged between two limit retaining rings on the same casing, several uniformly distributed square casings are hinged on one side of the installation ring close to each other, telescopic plates are inserted inside the square casings, the other ends of the telescopic plates inserted inside the square casings are hinged to each other, and rollers are arranged at the hinged parts between the telescopic plates through bearings; two inserting rods are fixedly connected to one side of the square casings far from each other, two uniformly distributed connecting holes are provided at one end of the telescopic plates inserted inside the square casings, the inserting rods are inserted inside the connecting holes, and extrusion springs used in cooperation with the telescopic plates are sleeved outside the inserting rods.

[0009] Optionally, anti-disengagement blocks are fixedly connected to the rod ends of the inserting rods far from the square casings, and limit retaining rings used in cooperation with the anti-disengagement blocks are embedded at one end of the connecting holes far from the rollers.

[0010] Optionally, the separating component includes a number of movable collars disposed at the gaps between the sleeves. The movable collars can move up and down within the gaps between the sleeves. Positioning retaining rings are provided inside each of the movable collars, and the inner diameter of the positioning retaining ring gradually decreases from top to bottom. A number of uniformly distributed limiting holes are formed at the upper end of the outer part of the movable collar. At the lower end inside the gaps between the sleeves, a number of uniformly distributed guide rods are fixedly connected. The guide rods and the limiting holes are adapted to each other. Control springs for cooperating with the movable collars are sleeved outside each of the guide rods, and the control springs are all located on the lower side of the outer part of the movable collar.

[0011] Optionally, the sleeve external seal includes a number of uniformly distributed pressure expansion rings provided on the sleeve. Inside one side of each pressure expansion ring, a first water passage, a second water passage, and a third water passage are respectively formed from bottom to top. The inside of the first water passage is connected to the inside of the sleeve in a through manner. One end of the second water passage close to the sleeve is connected to the middle part of the first water passage in a through manner. The middle part of the second water passage is connected to the middle part of the third water passage in a through manner. The middle part of the third water passage is connected to the bottom end inside the pressure expansion ring in a through manner. A first return valve is provided inside the first water passage. A second return valve is provided inside the second water passage. A closable valve that can move horizontally is provided inside the third water passage. A return pipe cavity is formed on one side of the inner wall of the pressure expansion ring close to the water passage. The upper end inside the pressure expansion ring and one side of the third water passage close to the sleeve are connected in a through manner through the return pipe cavity.

[0012] Optionally, the first return valve can control the opening and closing of the connection between the first water passage and the second water passage. The second return valve can control the opening and closing of the connection between the second water passage and the third water passage. The closable valve can control the opening and closing of the connection between the third water passage and the pressure expansion ring and the connection between the third water passage and the second water passage.

[0013] Optionally, the operating rubber plug mechanism includes a number of open rubber plugs and closed rubber plugs. The tail end of the closed rubber plug is made of a rigid material, and the radius of the tail end of the closed rubber plug gradually becomes smaller from top to bottom.

[0014] Optionally, the radius of the base at the tail end of the open rubber plug is smaller than the inner diameter of all the positioning retaining rings, and the tail end of the closed rubber plug is adapted to the positioning retaining ring.

[0015] Optionally, a sealing bushing for cooperating with the gap between the sleeves is provided on the inner wall of the connecting sleeve. When the movable collar moves to the bottommost position at the gap between the sleeves, the diversion hole is not blocked by the movable collar.

[0016] A packer-type staged cement injector provided by the present invention is fixed to the outside of the casing through mounting rings at both ends of a centralizing and straightening assembly. The telescopic plate in the centralizing and straightening assembly and the telescopic movement inside the square casing are used to offset the displacement between the two mounting rings caused by elastic deformation, ensuring that the centralizing and straightening assembly is located outside the casing, increasing the stability of the centralizer on the casing and the fixity of its position. After detecting the inside of the oil well, presetting the installation of the centralizer on the casing can play a greater role. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0019] Figure 2 is a three-dimensional partial structural schematic diagram of the present invention;

[0020] Figure 3 is the present invention Figure 2 the enlarged view at A in;

[0021] Figure 4 is the enlarged three-dimensional schematic of the connecting sleeve of the present invention Figure 1 ;

[0022] Figure 5 is the enlarged three-dimensional schematic of the connecting sleeve of the present invention Figure 2 ;

[0023] Figure 6 is the schematic of the state during the staged cement slurry injection stage of the present invention Figure 1 ;

[0024] Figure 7 is the schematic of the state during the staged cement slurry injection stage of the present invention Figure 2 ;

[0025] Figure 8 is the schematic of the state during the staged cement slurry injection stage of the present invention Figure 3 ;

[0026] Figure 9 is the schematic of the state during the staged cement slurry injection stage of the present invention Figure 4 ;

[0027] Figure 10 is the schematic of the state during the staged cement slurry injection stage of the present invention Figure 5 ;

[0028] Figure 11 It is a schematic diagram of the state of the staged cement slurry injection in the present invention Figure 6 ;

[0029] Figure 12 It is a schematic diagram of the state of the staged cement slurry injection in the present invention Figure 7 ;

[0030] Figure 13 It is a schematic diagram of the state of the staged cement slurry injection in the present invention Figure 8 ;

[0031] Figure 14 It is a schematic diagram of the non-flow state of the casing external packer in the present invention;

[0032] Figure 15 It is a schematic diagram of the flowing state of the casing external packer in the present invention;

[0033] Figure 16 It is a schematic diagram of the state after the casing external packer has flowed in the present invention;

[0034] Figure 17 It is a three-dimensional structural schematic diagram of the centralizing and straightening component in the present invention;

[0035] Figure 18 It is a schematic diagram of the internal structure of the centralizing and straightening component in the present invention;

[0036] Figure 19 It is a three-dimensional structural schematic diagram of the separating component in the present invention.

[0037] Reference numerals:

[0038] 1. Closed casing part; 2. Floating foot; 3. Centralizing and straightening component; 301. Mounting ring; 302. Square casing; 303. Telescopic plate; 304. Roller; 305. Insert rod; 306. Connecting hole; 307. Extrusion spring; 308. Anti-disengagement block; 309. Limit retaining ring; 4. Separating component; 401. Movable collar; 402. Positioning retaining ring; 403. Limiting hole; 404. Guide rod; 405. Control spring; 5. Casing external packer; 501. Pressurized expansion ring; 502. First water passage; 503. Second water passage; 504. Third water passage; 505. First return valve; 506. Second return valve; 507. Closing valve; 508. Return pipe cavity; 6. Operating rubber plug mechanism; 601. Opening rubber plug; 602. Closing rubber plug; 7. Casing; 8. Connecting sleeve; 9. Diversion hole; 10. Limit snap ring; 11. Check valve mechanism; 1101. Ball seat; 1102. Flow bottom hole; 1103. Valve ball; 12. Float collar; 13. Sealing bushing. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0040] As described above, when the current stage cementing device lowers the sealing casing by sleeving an elastic or rigid centralizer outside, the centralizer is used to maintain the centrality of the casing. During the cementing operation of oil wells at greater depths, it is often necessary to use an elastic centralizer to centralize the closed sleeve. The existing elastic centralizer uses a leaf spring type centralizer. When it penetrates into the interior of the oil well, due to the deformation of the leaf spring, the rings at both ends of the centralizer will expand and contract outside the casing. Due to the movement between the casing and the rings at both ends of the centralizer, the position of the centralizer will shift, easily changing the position of the centralizer outside the sleeve, affecting the centrality of the casing and the grouting operation of the cement slurry during the cementing operation.

[0041] In response to this, the present invention provides a packer type stage cementing device. This device can connect the centralizer and the outside of the casing in a form where both ends of the centralizer are fixed to the outside of the casing, and use the elasticity and expansion / contraction of the centralizer itself to offset the relative displacement at both ends of the centralizer caused by deformation.

[0042] The following will be combined with Figures 1 to 19 Specifically describe the present invention.

[0043] First Embodiment:

[0044] As Figures 1 to 3As shown in the figure, in this embodiment, the packer-type stage cementing device includes a closed casing member 1. The closed casing member 1 includes several casings 7 (taking three as an example in this application) evenly distributed along the axial direction, and there are gaps between every two adjacent upper and lower casings 7. A connecting sleeve 8 is provided between two adjacent upper and lower casings 7 to connect the two casings 7. A cylindrical sealing bushing 13 is fixedly connected to the inner wall of each connecting sleeve 8 for sealing. A number of evenly distributed diversion holes 9 are formed on the outer wall of the connecting sleeve 8, so that the inside of the connected closed casing member 1 can communicate with the oil well. After the closed casing member 1 is inserted into the inside of the oil well, an annulus is formed between the closed casing member 1 and the oil well, and the grouting work of the cement slurry is carried out inside the annulus. An activity collar 401 is arranged inside the gap between every two casings 7. The height of the activity collar 401 is less than the height of the gap between the casings 7, and the activity collar 401 can move up and down inside the gap between the casings 7. A number of evenly distributed limiting holes 403 are formed on the upper outer end of the activity collar 401 along the circular ring. A number of evenly distributed guide rods 404 are also fixedly connected to the lower end inside the gap between every two casings 7 along the circular ring distribution. Each guide rod 404 is inserted into the corresponding limiting hole 403 formed on the activity collar 401 to prevent the activity collar 401 from rotating. A control spring 405 is sleeved on each guide rod 404, and the control spring 405 is located on the lower outer side of the activity collar 401. Without the action of a certain external force, the control spring 405 jacks up the activity collar 401 upward, and can block the diversion holes 9 formed on the connecting sleeve 8 to complete the closure of the internal space of the casing 7.

[0045] And a positioning retaining ring 402 is arranged inside each activity collar 401. The positioning retaining ring 402 is as Figure 19 shown. There is an inward protrusion at the upper position, and starting from the protrusion position, it is connected to the inner bottom end of the activity collar 401 in the form of an inclined surface downward. A complete separation assembly 4 is composed of the activity collar 401, the positioning retaining ring 402, the limiting holes 403, the guide rods 404 and the control spring 405. Two limiting snap rings 10 are arranged on the outer part of each casing 7, and the two limiting snap rings 10 are fixed on the outer wall of the corresponding casing 7. A centralizing and straightening assembly 3 is arranged between the two limiting snap rings 10 on the outer part of the same casing 7. The centralizing and straightening assembly 3 mainly consists of two vertically distributed mounting rings 301, square casings 302 evenly distributed along the two mounting rings 301, a telescopic plate 303 inserted into the square casings 302, and rollers 304 arranged at the hinge points after the upper and lower telescopic plates 303 extend out of the square casings 302.

[0046] AsFigure 17 and Figure 18 As shown in Figure 17 and Figure 18 , the two mounting rings 301 above and below are arranged on one side close to each other of the two limit snap rings 10 outside the same sleeve 7. Both of the two mounting rings 301 are fixedly connected to the limit snap rings 10. A number of uniformly distributed square sleeves 302 are hinged on one side close to each other of the two mounting rings 301. At one end of each square sleeve 302 close to the hinge with the mounting ring 301, two inserting rods 305 are fixedly connected. A telescopic plate 303 is inserted into each square sleeve 302. The telescopic plates 303 arranged in the two square sleeves 302 face each other, and the other ends of the two opposite telescopic plates 303 inserted into the square sleeves 302 are hinged to each other. Through the rollers 304 arranged at the hinge of the two opposite telescopic plates 303, the friction between the centralizing and straightening assembly 3 and the inner wall of the oil well during the lowering of the cement injector is reduced.

[0047] When the cement injector is lowered, due to the uneven inner wall of the oil well, it will contact the rollers 304 of the centralizing and straightening assembly 3 and exert extrusion on the rollers 304. The rollers 304 extrude the two telescopic plates 303, causing the angle formed between the two telescopic plates 303 to become larger. After the angle becomes larger, the other ends of the telescopic plates 303 hinged to each other need to move away from each other to offset the distance change caused by the change in the angle. Two connecting holes 306 are opened at one end of each telescopic plate 303 inserted into the corresponding square sleeve 302. The connecting holes 306 are for the inserting rods 305 to be inserted. At one end of the square sleeve 302 close to the hinge end with the mounting ring 301, two extrusion springs 307 are arranged. Both of the two springs are correspondingly sleeved on the two inserting rods 305, and the two telescopic plates 303 are extruded towards the outside of the square sleeve 302, so that when the rollers 304 lose the extrusion of the inner wall of the oil well, the rollers 304 can move outwards again and fit towards the direction of the inner wall of the oil well.

[0048] When the two telescopic plates 303 are squeezed, they can move and retract into the interior of the square sleeve 302 to offset the misalignment movement of the centralizer caused by the two mounting rings 301 moving away from each other when the centralizer component 3 is squeezed and moving closer to each other during reset. At the same time, through the telescoping of the telescopic plate 303 inside the square sleeve 302 and the articulated rotation of the square sleeve 302 on the mounting ring 301, the problem of the roller 304 moving closer to or away from the sleeve 7 is offset. Depending on the articulated rotation of the square sleeve 302 on the mounting ring 301, the movement interference caused by the movement of the roller 304 to the telescopic plate 303 is offset. When the inner wall of the oil well does not squeeze the roller 304, the two compression springs 307 will squeeze out the telescopic plate 303. To prevent the telescopic plate 303 from being squeezed out of the interior of the square sleeve 302, an anti - detachment block 308 is fixedly connected to one end of each insertion rod 305 away from the connection with the square sleeve 302, and a limit retaining ring 309 is embedded inside each connection hole 306 near the inner end of the corresponding inserted square sleeve 302 to prevent the telescopic plate 303 from moving out of the interior of the square sleeve 302.

[0049] The elastic force of the spring is based on Hooke's law and is: , (Formula 1),

[0050] where, F is the restoring force exerted by the spring, with the unit of Newton ( N );

[0051] k is the spring progress coefficient or elastic coefficient, which reflects the ability of the spring to resist deformation and is related to the material, with the unit of Newton per meter ( N / m );

[0052] x is the displacement of the spring relative to the unloaded state, that is, the distance of elongation or shortening, with the unit of meter ( m ).

[0053] When lowering the cement injector, the telescopic plate 303 moves into the interior of the square sleeve 302 when the roller 304 is squeezed by the inner wall of the oil well. The amount of retraction of the telescopic plate 303 into the interior of the square sleeve 302 is the amount by which the compression spring 307 is compressed, which is x .

[0054] As Figures 6 to 13As shown in the figure, in this embodiment, when the rubber plug is lowered into the inside of the casing 7, the rubber plug abuts against the movable collar 401. Under the pressure of pressurization and pumping, the rubber plug is pumped into the inside of the movable collar 401. If the tail of the rubber plug does not get stuck inside the positioning retaining ring 402 inside the movable collar 401, the rubber plug will continue to move downward until it touches the bottom of the pipe. If the tail of the rubber plug gets stuck inside the positioning retaining ring 402, during the process of continuously applying downward pressure, the rubber plug will squeeze the movable collar 401 downward through the positioning retaining ring 402 until the movable collar 401 no longer blocks the diversion holes 9 opened on the outer wall of the connecting sleeve 8, so that the next stage of cement injection work can be carried out.

[0055] Therefore, an operating rubber plug mechanism 6 is provided inside the combined casing 7. The operating rubber plug mechanism 6 includes two types of rubber plugs, namely the open rubber plug 601 and the closed rubber plug 602. There are several of each type of rubber plug (in this application, taking the combination of three casings as an example, there are a total of four open rubber plugs 601 and two closed rubber plugs 602). As Figures 6 to 13 shown, after the three casings are combined, a floating shoe 2 is installed at the lower end outside the lowermost casing 7. Inside the floating shoe 2 is a check valve mechanism 11. Among them, the upper end inside the floating shoe 2 is a constriction that converges both upward and downward. A ball seat 1101 is provided inside the floating shoe 2. In the middle of the ball seat 1101 is a circular through-hole that communicates up and down. A number of evenly distributed flow-through bottom holes 1102 are opened around the center at the upper end outside the ball seat 1101. A valve ball 1103 is provided at the center of the upper end of the ball seat 1101. The valve ball 1103 can block the hole at the center of the upper end outside the ball seat 1101. When the valve ball 1103 moves upward, it can block the constriction at the upper end inside the floating shoe 2, so that the liquid or cement slurry inside the casing 7 can flow downward through the upper-end constriction of the floating shoe 2 and then through the inside of the flow-through bottom holes 1102 and flow into the annulus between the casing 7 and the inner wall of the oil well. However, when the pressure of the liquid or cement slurry in the annulus is relatively high and there is a tendency to flow back into the inside of the casing 7, after the valve ball 1103 moves upward to block the constriction, the backflow can be prevented to ensure the stability of cement slurry injection.

[0056] From Figures 6 to 13 it can be seen the operation process of cement slurry injection in each stage. First, before lowering the cement injector, measure the height distance from the bottom end of the floating shoe 2 to the diversion hole 9 outside the first connecting sleeve 8 counted from bottom to top, denoted as , and then measure the distance between the diversion holes 9 outside the two connecting sleeves 8. After placing the cement injector, measure the distance from the diversion hole 9 outside the second connecting sleeve 8 counted from bottom to top to the wellhead , after the grouting cement injector is lowered into the interior of the oil well, first inject drilling fluid into the interior of the casing. When injecting the drilling fluid, detect the height of the drilling fluid entering the annulus after flowing out of the interior of the casing 7 through a measuring instrument. When the height of the drilling fluid reaches and approaches the lowest diversion hole 9 (the error is less than 20 cm), record the volume of the injected drilling fluid, denoted as , the total volume inside the casing 7 is , then the volume of the cement slurry injected in the first stage is , continue to inject drilling fluid. Through the detection instrument, when the drilling fluid enters the interior of the annulus and is at a position less than 20 cm below the uppermost diversion hole 9, record the volume of the injected drilling fluid at this time as , then the volume of the cement slurry that needs to be injected in the second stage is , the volume of the finally filled drilling fluid is , then the third stage, which is the last stage of cement injection in this example, the volume of the cement slurry that needs to be injected is .

[0057] Before injecting the cement slurry, it is necessary to inject drilling fluid first. After flushing the mud cake inside the annulus, inject the spacer fluid. Use the spacer fluid to separate the drilling fluid and the cement slurry to avoid the cement slurry being affected by the drilling fluid. At the same time, the spacer fluid can clean the mud cake on the wellbore wall inside the annulus more thoroughly. Immediately after injecting the spacer fluid, inject of the cement slurry. After injecting the cement slurry, immediately pump an open plug 601 into the interior of the casing 7. After the open plug is placed inside the casing 7, it is necessary to pump into the casing not less than the volume of each individual casing 7 of the spacer fluid. Then lower a closed plug 602 and pump in of the cement slurry. After pumping in the cement slurry, place an open plug 601 again. Then repeat the method of pumping drilling fluid and closing the plug 602. The upper end of the open plug 601 is made of a soft material, and the radius is less than the inner diameter of the positioning retaining ring 402, so that the open plug 601 can move downward through the interior of the positioning retaining ring 402 and reach the bottom directly. The upper end of the closed plug 602 is made of a rigid material such as steel and other hard materials, and the inner diameter of the protrusion inside the positioning retaining ring 402 gradually decreases from top to bottom. In this way, the upper positioning retaining ring 402 will not block the descending closed plug 602, and the closed plug 602 is also placed in the order of the smaller radius at the tail end first, which can pass through the interior of the positioning retaining ring 402 with a larger inner diameter at the upper end. The protrusion inside the positioning retaining ring 402 is located higher, and is connected to the bottom end of the positioning retaining ring 402 in the form of an inclined plane. The outer edge of the plug can be squeezed and closely fit with the inner wall of the casing 7 or the positioning retaining ring 402, which is convenient for pressure application.

[0058] In order to keep the casing stable after each stage of cementing operation, an external casing packer 5 is provided outside each casing 7. The external casing packer 5 is located below the centralizing and straightening assembly 3. The external casing packer 5 consists of three water flow channels, three valves and a reflux pipeline. Among them, the external casing packer 5 includes a pressurized expansion ring 501 sleeved outside the casing 7. The outside of the pressurized expansion ring 501 is made of deformable rubber material and is hollow inside. At the lower end of the inner side of the pressurized expansion ring 501, three water flow channels are opened from bottom to top, which are called the first water flow channel 502, the second water flow channel 503 and the third water flow channel 504 in sequence from bottom to top. As Figures 14 to 16 shown, one end of the first water flow channel 502 close to the casing 7 is connected to the inside of the casing 7 through a small hole channel, and the middle position of the first water flow channel 502 penetrates to one end of the second water flow channel 503 close to the casing 7. The middle part of the second water flow channel 503 penetrates to the middle section of the inside of the third water flow channel 504. The middle section of the inside of the third water flow channel 504 penetrates to the bottom end of the hollow inside of the pressurized expansion ring 501. And the through-channel between the third water flow channel 504 and the pressurized expansion ring 501 is on the same vertical line as the through-channel between the second water flow channel 503 and the third water flow channel 504.

[0059] At the starting position, a first return valve 505 is arranged inside the first water flow channel 502, and a second return valve 506 is arranged inside the second water flow channel 503. Both return valves are spring-type return valves, and the two return valves are respectively fixed at one end of the two water flow channels far from the casing 7. The two return valves are extruded towards the casing 7 by springs. The starting position of the first return valve 505 blocks the through-channel inside the casing 7 and the first water flow channel 502, and blocks the communication cavity between the first and second water flow channels. The starting position of the second return valve 506 blocks the through-channel between the second and third water flow channels, but does not block the communication position between the first and second water flow channels. In this way, when isolating liquid or other expanding liquid enters from the first water flow channel 502, the first return valve 505 is pushed and flows into the second water flow channel 503, and the second return valve 506 is also moved in the direction away from the casing 7.

[0060] Inside the third water flow channel 504, a laterally movable closing valve 507 is arranged. The closing valve 507 consists of two cylindrical plugs and a thin rod in the middle. The initial position of the closing valve 507 is as Figure 14 shown. The thin rod in the middle is at the communication position between the second and third water flow channels and does not block the flow of isolating liquid and other liquids from the second water flow channel 503 to the inside of the third water flow channel 504. The farthest distance that the closing valve 507 moves towards the casing 7 is as Figure 14As shown, it will not block the connection between the return pipe cavity 508 opened on the inner wall of the pressurized expansion ring 501 and the third water passage 504, and move farthest in the direction away from the casing 7, such as Figure 16 As shown, it will not leave the state of closing the connection between the third water passage 504 and the inside of the pressurized expansion ring 501. Figure 14 This is the initial state, that is, the state when no isolation liquid is injected under pressure, etc. Figure 15 This is the state during the process of injecting under pressure. Figure 16 After the injection under pressure is completed, since the isolation liquid flows into the inside of the pressurized expansion ring 501 through the inside of the three channels, etc., when the inside of the pressurized expansion ring 501 is filled, because the return pipe cavity 508 is very thin, the pressurized expansion ring 501 expands first. When the liquid inside expands to flow through the inside of the return pipe cavity 508 into the inside of the third water passage 504 due to pressure, it will also push the closing valve 507 to move in the direction away from the casing, completely closing the passage. The expanded pressurized expansion ring 501 squeezes the external cement slurry, and finally ensures the stability of the corresponding position of the casing 7. The elastic force calculation of the springs in the two rebound valves is as shown in (Formula 1).

[0061] Through the above design, the present invention performs a staged grouting operation for the oil well by means of segmented injection of cement slurry, rubber plugs, and isolation liquid, such as Figures 6 to 13 As shown, for each state in the process of injecting cement slurry, after the injection of drilling fluid for cleaning is completed, isolation liquid is injected into the inside of the casing 7. After the inside of the annulus is completely filled with isolation liquid, the isolation liquid inside the casing 7 is pumped out by pumping. Then, cement slurry not less than is injected into the inside of the casing 7. Then, an open rubber plug 601 is added behind the cement slurry. After the open rubber plug 601 is added, isolation liquid is added. The maximum expansion volume that can be filled with liquid inside the pressurized expansion ring 501 is , and the volume of the added isolation liquid is . Then, a closed rubber plug 602 is added and pressurization starts.

[0062] The spring elastic force of the two rebound valves is , and the pressure at the lowest separating component 4 is , (Formula 2) where ρ is the density of the liquid;

[0063] P is the pressure; h is the vertical distance or depth from the free liquid surface to this point; g is the acceleration of gravity (about 9.8 ).

[0064] The effective area of one end of the first rebound valve 505 close to the casing 7 is A, at the total pressure where the corresponding separation component 4 is located is , where is the total pressure at this position, is the pressure when filling the isolation fluid, is the pressure applied externally from the upper end of the cement injector when squeezing the isolation fluid into the inside of the pressurized expansion ring 501. The pressure of the spring in the return valve should satisfy less than , and greater than conditions to ensure that the return valve will not open during injection and can only open during pressurization. The isolation fluid passes through the inside of the first, second, and third water passage cavities. After the inside of the pressurized expansion ring 501 expands, it then passes through the inside of the return pipe cavity 508 to squeeze the closing valve 507 away from the casing 7, closing the inside of the pressurized expansion ring 501.

[0065] Second Embodiment:

[0066] And this staged cement injector can also perform a one-time cementing operation in a relatively uniform oil well or an oil well with a relatively short depth. First, place this cement injector into the oil well. First, pump drilling fluid into the inside of the casing 7. After the drilling fluid flushes and treats the mud cake in the annulus, then inject the isolation fluid and cement slurry into the inside of the casing 7. Use the isolation fluid to completely separate the cement slurry and the drilling fluid. As the pumping progresses, the cement slurry squeezes both the isolation fluid and the drilling fluid out of the annulus completely. At the wellhead position, use a circulation pump for extraction operations and inject a certain volume of cement slurry through the corresponding design elevation. For example, if the volume of the annulus is V , then inject more than V of cement slurry (to prevent excessive cement slurry from flowing out of the wellhead). Then immediately place an open rubber plug 601 and use pumping to add drilling fluid or isolation fluid into the inside of the casing 7 for pressurization until the rubber plug touches the bottom. All the cement mortar inside the casing 7 is squeezed out. After further pressurization, the subsequently injected isolation fluid enters the inside of the pressurized expansion ring 501 through the inside of the three cavities, squeezing the cement slurry inside the annulus to fix the casing.

[0067] Therefore, when this embodiment is specifically implemented, the one-way valve mechanism 11 inside the floating foot 2 at the bottom serves as a closed control valve to prevent the cement inside the annulus from flowing back. The floating foot 2 and the float collar 12 are used to guide the cement injector during lowering. During lowering, the roller 304 of the centralizing and straightening assembly 3 contacts the wellbore wall for straightening to ensure the concentricity, i.e., the centrality, between the cement injector and the axis inside the oil well. Similarly, the telescopic plate 303 is telescoped inside the square casing 302, and the square casing 302 rotates around the hinge of the mounting ring 301 to convert the movement amount of the straightener caused by the extrusion of the wellbore wall, which makes the roller 304 move closer to the casing 7, into the retraction of the two telescopic plates 303 into the square casing 302, ensuring that the two mounting rings 301 do not move, increasing the stability and position fixation of the straightener on the casing 7. After detecting the inside of the oil well, presetting and installing the straightener on the casing 7 can play a greater role.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A packer-type staged cementing tool, characterized in that, including: a closed casing member (1) composed of several sleeves (7) uniformly distributed along the axis, with gaps between the sleeves (7), the sleeves (7) being connected by a connecting sleeve (8) provided therebetween, the outer side wall of the connecting sleeve (8) being provided with several uniformly distributed diversion holes (9), and uniformly distributed limit snap rings (10) being provided outside each of the sleeves (7); a floating foot (2) provided at the outer bottom end of the closed casing member (1), a check valve mechanism (11) being provided inside the floating foot (2), and a floating collar (12) being provided on the lower side outside the closed casing member (1); a centralizing and straightening assembly (3) provided on each sleeve (7), the centralizing and straightening assembly (3) being located between two limit snap rings (10) of the same sleeve (7); the centralizing and straightening assembly (3) includes a mounting ring (301) provided between two limit snap rings (10) on the same sleeve (7), several uniformly distributed square sleeves (302) being hinged to one side of the mounting ring (301) close to each other, telescopic plates (303) being inserted into the square sleeves (302), the other ends of the telescopic plates (303) inserted into the square sleeves (302) being hinged to each other, and rollers (304) being provided at the hinge joints between the telescopic plates (303) through bearings; two insertion rods (305) are fixedly connected to one side of the square sleeve (302) away from each other, two uniformly distributed connection holes (306) are provided at one end of the telescopic plate (303) inserted into the square sleeve (302), the insertion rods (305) are inserted into the connection holes (306), and compression springs (307) for cooperating with the telescopic plates (303) are sleeved outside the insertion rods (305); a separation assembly (4) provided at the gap between the sleeves (7); an outer casing packer (5) provided outside the sleeve (7); an operating rubber plug mechanism (6) provided inside the sleeve (7).

2. The packer-type staged cement injector according to claim 1, wherein: the check valve mechanism (11) includes a ball seat (1101) provided inside the floating foot (2), a circular hole communicating up and down is provided at the center of the ball seat (1101), several flow bottom holes (1102) distributed around the central circular hole are provided at the upper edge of the ball seat (1101), a valve ball (1103) for cooperating with the circular hole at the center is provided at the upper end of the ball seat (1101), the upper end inside the floating foot (2) is a necking for cooperating with the valve ball (1103), the inside of the floating foot (2) is connected to the inside of the sleeve (7) in a through manner, and the valve ball (1103) can move up and down between the ball seat (1101) and the necking.

3. The packer-type staged cementing tool according to claim 1, wherein: Anti - detachment blocks (308) are fixedly connected to the rod ends of the insertion rods (305) far away from the square sleeves (302), and limit retaining rings (309) for cooperating with the anti - detachment blocks (308) are embedded at one ends of the connection holes (306) far away from the rollers (304).

4. The packer-type staged cementing tool according to claim 1, wherein: The separation assembly (4) includes a number of movable collars (401) arranged at the gaps between the sleeves (7). The movable collars (401) can move up and down within the gaps between the sleeves (7). Positioning retaining rings (402) are arranged inside the movable collars (401), and the inner diameters of the positioning retaining rings (402) gradually decrease from top to bottom; A number of uniformly distributed limit holes (403) are opened at the upper ends of the outer sides of the movable collars (401). A number of uniformly distributed guide rods (404) are fixedly connected to the lower ends inside the gaps between the sleeves (7). The guide rods (404) are adapted to the inside of the limit holes (403). Control springs (405) for cooperating with the movable collars (401) are sleeved on the outer sides of the guide rods (404), and the control springs (405) are all located on the lower sides of the outer sides of the movable collars (401).

5. The packer-type staged cementing tool according to claim 1, wherein: The sleeve external packer (5) includes a number of uniformly distributed pressure - expanding rings (501) arranged on the sleeves (7). First water - passing channels (502), second water - passing channels (503), and third water - passing channels (504) are respectively opened from bottom to top on one side inside the pressure - expanding rings (501). The inside of the first water - passing channel (502) is connected to the inside of the sleeve (7) in a through - connection manner. One end of the second water - passing channel (503) close to the sleeve (7) is connected to the middle of the first water - passing channel (502) in a through - connection manner. The middle of the second water - passing channel (503) is connected to the middle of the third water - passing channel (504) in a through - connection manner. The middle of the third water - passing channel (504) is connected to the bottom end inside the pressure - expanding ring (501) in a through - connection manner; A first return valve (505) is arranged inside the first water - passing channel (502). A second return valve (506) is arranged inside the second water - passing channel (503). A closable valve (507) that can move horizontally is arranged inside the third water - passing channel (504). A return pipe cavity (508) is opened on one side of the inner wall of the pressure - expanding ring (501) close to the water - passing channels. The upper end inside the pressure - expanding ring (501) and one side of the third water - passing channel (504) close to the sleeve (7) are connected in a through - connection manner through the return pipe cavity (508).

6. The packer-type staged cementing tool according to claim 5, wherein: The first return valve (505) can control the opening and closing of the connection between the first water - passing channel (502) and the second water - passing channel (503). The second return valve (506) can control the opening and closing of the connection between the second water - passing channel (503) and the third water - passing channel (504). The closable valve (507) can control the opening and closing of the connection between the third water - passing channel (504) and the pressure - expanding ring (501) and the connection between the third water - passing channel (504) and the second water - passing channel (503).

7. The packer-type stage cementing tool according to claim 1, characterized in that: The operating rubber stopper mechanism (6) includes a plurality of opening rubber stoppers (601) and closing rubber stoppers (602). The tail end of the closing rubber stopper (602) is made of rigid material, and the radius of the tail end of the closing rubber stopper (602) gradually decreases from top to bottom.

8. The packer-type stage cementing tool according to claim 4 or 7, characterized in that: The base radius of the tail end of the opening rubber stopper (601) is smaller than the inner diameter of all the positioning retaining rings (402), and the tail end of the closing rubber stopper (602) is adapted to the positioning retaining ring (402).

9. The packer type staged cementing tool according to claim 4, wherein A sealing bushing (13) for using the gap between the mating sleeves (7) is arranged on the inner wall of the connecting sleeve (8). When the movable collar (401) moves to the bottommost position at the gap between the sleeves (7), the diversion hole (9) is not blocked by the movable collar (401).

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