Forward and reverse circulation combined well cementation tool and well cementation method

Abstract

The invention discloses a positive and negative circulation combined well cementation tool and a well cementation method, belongs to the technical field of oil exploitation, and aims to solve the problem of poor adaptability of well cementation by purely using positive circulation or reverse circulation. The positive and negative circulation combined well cementation tool comprises a cross circulation short section (2) and a reverse circulation well cementation intercepting float shoe (3) which are arranged up and down; the reverse circulation well cementation intercepting float shoe (3) comprises an intercepting assembly (33) and a one-way valve (32), and the intercepting assembly (33) comprises a control module (332) and an intercepting module (333). According to the positive and negative circulation combined well cementation tool and the well cementation method, the advantages of positive circulation and negative circulation well cementation processes are fully utilized, pressure balance and cement paste conveying are achieved, the well cementation problem of an ultra-long sealing section and a complex stratum is solved, the well cementation quality and the construction efficiency are greatly improved, and the well cementation cost is reduced. The method is suitable for oil and gas well cementing operation under complex geological conditions.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, specifically to a cementing tool that combines forward and reverse circulation, or a cementing method that combines forward and reverse circulation. Background Technology

[0002] Forward circulation cementing is a traditional cementing process, primarily used to inject cement slurry into oil and gas wellbores to achieve formation sealing and isolation. Reverse circulation cementing is a specialized cementing process, distinct from traditional forward circulation cementing. In forward circulation cementing, cement slurry is injected from inside the casing and displaces drilling fluid into the annulus between the wellbore and casing, ultimately sealing the formation. Reverse circulation cementing, however, injects cement slurry directly into the annulus between the casing and wellbore. By pushing the drilling fluid back to the surface from inside the casing, the cement slurry directly fills the annulus, achieving efficient sealing.

[0003] As oil and gas exploration and development targets become increasingly complex and geological conditions become increasingly demanding, the engineering and technical difficulties also increase. For certain special formations, it is not possible to use forward or reverse circulation cementing processes alone, such as cementing of oil and gas wells with ultra-long cementing sections, formations with low pressure bearing capacity, and those facing easy leakage, large temperature differences, and high temperature and high pressure environments. Summary of the Invention

[0004] To address the poor adaptability of using only forward or reverse circulation cementing, this invention provides a cementing tool and method that combines forward and reverse circulation. This combined cementing tool and method fully utilizes the advantages of both forward and reverse circulation cementing processes, achieving pressure balance and cement slurry delivery, while also solving the challenges of cementing ultra-long cementing sections and complex formations. This greatly improves cementing quality and construction efficiency, and is suitable for cementing operations in oil and gas wells under complex geological conditions.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A cementing tool combining forward and reverse circulation includes an upper and lower cross-circulation sub and a reverse circulation cementing shut-off float. The reverse circulation cementing shut-off float includes an outer shell, which is an upright cylindrical structure. The outer shell contains a shell wall and an internal flow channel. The internal flow channel contains a shut-off assembly and a one-way valve arranged vertically. The shut-off assembly includes an upper shell, which is also an upright cylindrical structure. The upper shell contains an upper cylindrical wall and an upper inner flow channel. The upper cylindrical wall contains a control module and a shut-off module. The control module can control the shut-off module to close the upper inner flow channel.

[0007] A cementing method combining forward and reverse circulation, wherein the cementing method employs the aforementioned cementing tool combining forward and reverse circulation, and the cementing method combining forward and reverse circulation includes the following steps in sequence:

[0008] Step 1: Preparations before construction;

[0009] The reverse circulation cementing cutoff float receives the excitation target signal via a receiver on the ground and stores the excitation target signal in memory via a control unit;

[0010] Step 2: Lower the cementing tool with the combined forward and reverse circulation into the wellbore;

[0011] Step 3: Inject flushing fluid into the cementing tool with combined forward and reverse circulation;

[0012] Step 4: Sequentially inject signal cement slurry and cementing cement slurry into the combined forward and reverse circulation cementing tool. The signal cement slurry is a mixture of a trigger beacon and cement slurry, and the volume of the signal cement slurry is 0.5 m³. 3 -2m 3 The volume of the cement slurry is equal to the volume of the lowest wellbore annulus;

[0013] Step 5: Inject displacement fluid into the cementing tool with combined forward and reverse circulation;

[0014] Step 6: The signal cement slurry flows to the reverse circulation cementing cutoff float. The control unit compares the excitation signal emitted by the excitation beacon with the excitation target signal stored in the memory. The control module controls the cutoff module to close the upper inner flow channel.

[0015] The beneficial effects of the present invention are: the cementing tool and cementing method combining forward and reverse circulation fully utilize the advantages of forward and reverse circulation cementing processes, achieving pressure balance and cement slurry delivery, and solving the problems of cementing in ultra-long cementing sections and complex formations, greatly improving cementing quality and construction efficiency, and is suitable for cementing operations in oil and gas wells under complex geological conditions. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1 This is a schematic diagram of the cementing tool with combined forward and reverse circulation as described in this invention in the wellbore.

[0018] Figure 2 This is a schematic diagram of a cross-loop short section.

[0019] Figure 3 This is a schematic diagram of the flow-blocking component of the reverse circulation cementing flow-blocking float being in the closed state.

[0020] Figure 4This is a schematic diagram of the flow-blocking component of the reverse circulation cementing flow-blocking float in the open state.

[0021] Figure 5 This is a schematic diagram of the flow interception component.

[0022] Figure 6 yes Figure 5 Enlarged diagram of part A in the middle.

[0023] Figure 7 This is a schematic diagram of the control module.

[0024] Figure 8 This is a diagram showing the flow control component in the off state.

[0025] Figure 9 This is the connection diagram of the control module.

[0026] Figure 10 This is the control logic diagram of the interception component.

[0027] Figure 11 This is a schematic diagram of cementing after using a cementing tool that combines single-stage forward and reverse circulation.

[0028] Figure 12 This is a schematic diagram of a cementing tool using a two-stage forward and reverse circulation system after cementing.

[0029] Explanation of reference numerals in the attached figures:

[0030] 1. Casing; 2. Cross-circulation sub; 3. Reverse circulation cementing cutoff float; 4. Wellbore annulus; 5. Internal cavity of casing; 6. Wellbore;

[0031] 21. Upper connector section; 22. Lower connector section; 23. Inner section; 24. Sealing structure; 25. First channel; 26. Second channel;

[0032] 31. Housing; 32. Check valve; 33. Flow control assembly;

[0033] 311. Shell wall; 312. Internal flow channels;

[0034] 321. Lower housing; 322. Valve core; 323. Valve stem; 324. Support plate; 325. First spring;

[0035] 3211. Lower cylinder wall; 3212. Lower inner flow channel;

[0036] 331. Upper casing; 332. Control module; 333. Current interception module;

[0037] 3311. Upper cylinder wall; 3312. Upper inner flow channel; 3313. Annular inner cavity; 3314. Outer peripheral wall; 3315. Inner peripheral wall;

[0038] 3321. Signal detector; 3322. Control unit; 3323. Execution unit; 3324. Receiver; 3325. Memory; 3326. Power supply; 3327. Electromagnetic actuator; 3328. Magnetic stop pin;

[0039] 3331, baffle slot; 3332, second spring; 3333, baffle; 3334, third spring; 3335, baffle slide; 3336, stop pin slide;

[0040] 101. First wellbore annulus section; 102. First casing internal cavity section; 103. Second wellbore annulus section; 104. Second casing internal cavity section; 105. Third wellbore annulus section; 106. Third casing internal cavity section; 107. Non-cement slurry area; 108. Cement slurry area. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] For ease of understanding and description, the following description of the present invention uses absolute positional relationships. Unless otherwise specified, the directional term "above" indicates... Figure 1 The direction above, the directional word "down" indicates Figure 1 The lower side of the middle, the directional word "left" indicates Figure 1 The left side of the direction, the directional word "right" indicates Figure 1 The right-hand direction in the text, the directional word "front" indicates perpendicular to. Figure 1 The direction of the paper and pointing inwards from the paper; the directional word "back" indicates perpendicular to the paper. Figure 1 The orientation of the paper is directed towards the outer edge of the paper. This invention is described from the perspective of a reader or user, but the aforementioned directional terms should not be construed as limiting the scope of protection of this invention. Regarding the dimensions and angles of the components, those skilled in the art can determine them specifically according to actual needs.

[0043] like Figure 1 As shown in the embodiment of the present invention, a cementing tool combining forward and reverse circulation includes a cross-circulation sub 2 and a reverse circulation cementing cut-off float 3 arranged vertically. The cross-circulation sub 2 is incorporated into the cementing tool, and the reverse circulation cementing cut-off float 3 is used at the bottom of the tool. After cementing is completed, the annulus below the cross-circulation sub 2 is sealed with cement slurry, while the annulus above the cross-circulation sub 2 and the casing contain non-cement slurry fluids such as water and drilling fluid.

[0044] like Figure 2As shown, the cross-circulation sub 2 prevents the wellbore annulus 4 above the cross-circulation sub 2 from communicating with the wellbore annulus 4 below the cross-circulation sub 2. The cross-circulation sub 2 contains a first channel 25 and a second channel 26. The first channel 25 allows the casing cavity 5 above the cross-circulation sub 2 to communicate with the wellbore annulus 4 below the cross-circulation sub 2. The second channel 26 allows the casing cavity 5 below the cross-circulation sub 2 to communicate with the wellbore annulus 4 above the cross-circulation sub 2.

[0045] The cross-circulation sub 2 includes an inner section 23 with inner and outer sleeves and a sealing structure 24. The upper end of the inner section 23 is provided with an upper connector section 21, which can be an internal thread section. The lower end of the inner section 23 is provided with a lower connector section 22, which can be an external thread section. The inner section 23 and the sealing structure 24 are sealed together. The sealing structure 24 can be sealed together with the inner surface of the well wall 6.

[0046] like Figure 2 As shown, the inner segment 23 is an upright cylindrical structure. The upper end of the first channel 25 is located on the upper surface of the inner segment 23, the lower end of the first channel 25 is located on the side circumferential surface of the inner segment 23, and the lower end of the first channel 25 is lower than the sealing structure 24. The upper end of the second channel 26 is located on the side circumferential surface of the inner segment 23, the upper end of the second channel 26 is higher than the sealing structure 24, and the upper end of the second channel 26 is located on the lower surface of the inner segment 23.

[0047] The packer structure 24 can be selected from different existing packer mechanisms depending on the operating conditions. For example, the packer structure 24 can be an oil- or water-swellable packer, a hydraulic packer, etc. The packer structure 24 is used to seal the wellbore annulus, preventing the wellbore annulus above and below the sub from communicating.

[0048] like Figures 3 to 4 As shown, the reverse circulation cementing cutoff float 3 includes an outer shell 31, which is an upright cylindrical structure. The outer shell 31 contains a shell wall 311 and an internal flow channel 312. The internal flow channel 312 contains a cutoff assembly 33 and a one-way valve 32 arranged vertically. The cutoff assembly 33 contains an upper shell 331, which is also an upright cylindrical structure. The upper shell 331 contains an upper cylindrical wall 3311 and an upper inner flow channel 3312. The upper cylindrical wall 3311 contains a control module 332 and a cutoff module 333. The control module 332 can control the cutoff module 333 to close the upper inner flow channel 3312.

[0049] In the one-way valve 32, the one-way valve 32 includes a lower housing 321, which is also an upright cylindrical structure. The lower housing 321 and the outer housing 31 are matched and sealed together. The lower housing 321 includes a lower cylindrical wall 3211 and a lower inner flow channel 3212. The inlet end of the lower inner flow channel 3212 faces downward and the outlet end of the lower inner flow channel 3212 faces upward. The lower inner flow channel 3212 contains a valve stem 323 and a valve core 322 connected vertically. The valve stem 323 is connected to the lower housing 321 through a support orifice plate 324. The valve core 322 is connected to the support orifice plate 324 through a first spring 325. The first spring 325 can provide a restoring force to the valve core 322. The one-way valve 32 is normally closed.

[0050] The axes of the outer casing 31, the one-way valve 32, and the flow-stopping assembly 33 coincide. The upper end of the outer casing 31 is the outlet end of the reverse circulation cementing flow-stopping float 3, and the lower end of the outer casing 31 is the inlet end of the reverse circulation cementing flow-stopping float 3. The upper end of the outer casing 31 has an internal thread, and the lower end has an external thread. The inlet end of the lower inner flow channel 3212 is connected to the inlet end of the reverse circulation cementing flow-stopping float 3, and the outlet end of the upper inner flow channel 3312 is connected to the outlet end of the reverse circulation cementing flow-stopping float 3. The lower cylinder wall 3211 contains an annular valve seat. The one-way valve 32 functions the same as a regular check valve; fluid can only enter through the inlet and exit through the outlet of the one-way valve 32, but cannot enter through the outlet or exit through the inlet.

[0051] like Figures 3 to 8 As shown, under normal circumstances, the one-way valve 32 is in the normally closed state, with the valve core 322 sealed to the valve seat and the first spring 325 compressed. Fluid can enter the lower inner flow channel 3212 from the inlet end, pushing the valve core 322 and valve stem 323 upwards. The valve core 322 disengages from the valve seat, and the fluid flows through the through holes in the valve core 322 and the support orifice plate 324 before exiting from the outlet end of the lower inner flow channel 3212. At this time, the one-way valve 32 is in the open state. After the fluid pressure disappears, the first spring 325 provides a restoring force to the valve core 322, restoring the sealed connection between the valve core 322 and the valve seat, and the one-way valve 32 returns to the closed state.

[0052] In the flow-stopping assembly 33, the upper shell 331 and the outer shell 31 are matched and sealed together. An annular inner cavity 3313 is provided inside the upper cylinder wall 3311. The annular inner cavity 3313 is used to install the control module 332 and the flow-stopping module 333. Both the control module 332 and the flow-stopping module 333 are located inside the annular inner cavity 3313. The upper inner flow channel 3312 extends through the upper shell 331 along the axial direction of the upper shell 331. The inlet end of the upper inner flow channel 3312 faces downward and the outlet end of the upper inner flow channel 3312 faces upward. The inlet end of the upper inner flow channel 3312 is connected to the outlet end of the lower inner flow channel 3212. The upper shell 331 is made of erosion-resistant metal, and its physical properties are not lower than those of the casing.

[0053] like Figure 9 As shown, the control module 332 receives and stores the excitation signal locally before entering the well, and controls the actuator to perform actions when the excitation signal is detected after entering the well. The control module 332 contains a signal detector 3321, a control unit 3322, and an execution unit 3323 connected in sequence. The control unit 3322 is connected to a memory 3325. The signal detector 3321 can detect electrical, acoustic, or magnetic signals within the upper inner flow channel 3312 in real time. The memory 3325 stores target signal information, and the signals stored in the memory 3325 can be read and written by the controller. The execution unit 3323 can begin executing actions after receiving an action execution command.

[0054] like Figure 10 As shown, the signal detector 3321 can be an existing electrical signal, acoustic signal, or magnetic signal detection sensor. The signal detector 3321 can detect electrical, acoustic, or magnetic signals in the upper inner flow channel 3312 in real time and send the real-time detection signal to the control unit 3322. The control unit 3322 compares the real-time detection signal with the target signal stored in the memory 3325 in real time. When the real-time detection signal matches the target signal, the control unit 3322 sends a control command to the execution unit 3323, which controls the flow interception module 333 to close the upper inner flow channel 3312.

[0055] like Figure 9 As shown, the control unit 3322 is also connected to a receiver 3324 and a power supply 3326. There can be one or more receivers 3324. The receivers 3324 are used to receive excitation signals when on the surface. The control unit 3322 can receive the target signal through the receivers 3324 and store it in the memory 3325. The power supply 3326 can be an existing dry cell battery or a rechargeable battery. The function of the power supply 3326 is to supply power to the control module 332, ensuring that the cementing tool with the forward and reverse circulation can operate autonomously, controllably, and reliably. The operating time of the power supply 3326 is no less than 1.5 times the total time from the start of casing installation to the end of cementing operations.

[0056] like Figures 5 to 8 As shown, the execution unit 3323 includes an electromagnetic actuator 3327 and a magnetic stop pin 3328. The electromagnetic actuator 3327 can employ existing technology, such as an electromagnet. The electromagnetic actuator 3327 can use its own generated electromagnetic force to attract the magnetic stop pin 3328 and move the magnetic stop pin 3328 toward the electromagnetic actuator 3327.

[0057] The control module 332 and the flow-blocking module 333 can be connected vertically or integrated. The flow-blocking module 333 is made of metal or erosion-resistant material and is used to cooperate with the actuator to close the fluid channel. The flow-blocking module 333 contains a baffle 3333 and a second spring 3332 connected in sequence. The baffle 3333 is perpendicular to the axis of the upper housing 331. The flow-blocking assembly 33 is normally open, meaning that under normal conditions, the flow-blocking assembly 33 is in the open state, and the upper inner flow channel 3312 is also in the open state. When the upper inner flow channel 3312 is in the open state, the baffle 3333 is completely located inside the upper cylinder wall 3311, the magnetic stop pin 3328 is inserted into the baffle 3333, the second spring 3332 is in the compressed state, and the magnetic stop pin 3328 can prevent the baffle 3333 from moving along the diameter direction of the upper housing 331.

[0058] One end of the second spring 3332 is connected to one end of the baffle 3333. When the flow-stopping component 33 needs to be closed, that is, when the upper inner flow channel 3312 is closed, the electromagnetic actuator 3327 can cause the magnetic stop pin 3328 to disengage from the baffle 3333, and the second spring 3332 can cause the baffle 3333 to enter the upper inner flow channel 3312 and close the upper inner flow channel 3312. At this time, the flow-stopping component 33 is in the closed state, that is, the upper inner flow channel 3312 is also in the closed state.

[0059] The upper cylinder wall 3311 includes an outer peripheral wall 3314 and an inner peripheral wall 3315. The outer peripheral wall 3314 is sleeved outside the inner peripheral wall 3315. The other end of the second spring 3332 is connected to the outer peripheral wall 3314. The upper cylinder wall 3311 contains a baffle slide 3335. The extension direction of the baffle slide 3335 is perpendicular to the axis of the upper cylinder wall 3311. The baffle 3333 is matched and inserted into the baffle slide 3335. The baffle 3333 can slide along the baffle slide 3335. The inner surface of the inner peripheral wall 3315 contains a baffle groove 3331. When the baffle 3333 closes the upper inner flow channel 3312, the other end of the baffle 3333 is matched and inserted into the baffle groove 3331.

[0060] like Figures 5 to 8 As shown, the upper cylinder wall 3311 (i.e., the annular inner cavity 3313) may also contain a stop pin slide 3336. The extension direction of the stop pin slide 3336 is parallel to the axis of the upper cylinder wall 3311. The magnetic stop pin 3328 is matched and inserted into the stop pin slide 3336. The magnetic stop pin 3328 can slide along the stop pin slide 3336. The electromagnetic actuator 3327, the magnetic stop pin 3328 and the baffle 3333 are arranged sequentially from top to bottom. In order to prevent the magnetic stop pin 3328 from disengaging from the baffle 3333 when it needs to disengage from the baffle 3333, a third spring 3334 is connected between the electromagnetic actuator 3327 and the magnetic stop pin 3328. The third spring 3334 is usually in a natural state.

[0061] In the above description, once the baffle 3333 closes the upper inner flow channel 3312, it cannot be opened again. To allow the baffle 3333 to freely open and close the upper inner flow channel 3312, the actuator 3323 can be an electric push rod connected to the baffle 3333, which can move the baffle 3333 left and right. Alternatively, the actuator 3323 can also contain a motor, gear, and rack connected in sequence, with the rack connected to the baffle 3333, thereby allowing the baffle 3333 to move left and right.

[0062] In the cementing tool combining forward and reverse circulation, the reverse circulation cementing cutoff float 3 is located at the lower end of the cementing tool combining forward and reverse circulation. The cementing tool combining forward and reverse circulation includes one or more cross circulation short sections 2, which are arranged in the vertical direction. Two adjacent cross circulation short sections 2 can be directly or indirectly connected by one or more casings 1. Two adjacent casings 1 can be connected by a reverse circulation float collar. The lowermost cross circulation short section 2 and the reverse circulation cementing cutoff float 3 can be directly or indirectly connected by one or more casings 1.

[0063] In the aforementioned cementing tools combining forward and reverse circulation, a cementing tool using one cross-circulation sub2 can be called a single-stage forward and reverse circulation cementing tool; a cementing tool using three cross-circulation sub2s can be called a two-stage forward and reverse circulation cementing tool; and a cementing tool using multiple cross-circulation sub2s can be called a multi-stage forward and reverse circulation cementing tool. The reverse circulation float collar controls fluid flow in only one direction, ensuring that fluid can only flow from the wellbore annulus to the casing, while preventing fluid from flowing from the casing to the wellbore annulus.

[0064] The design position of the cross circulation sub 2 in the cementing tool with combined forward and reverse circulation is as follows: the cross circulation sub 2 is generally designed at the junction of cement slurry and displacement fluid, and the design position of the cross circulation sub 2 is the top of the sealing layer. For example, if it is necessary to seal the wellbore annulus 500m from the bottom of the well, the cross circulation sub 2 is added to the casing string at the corresponding distance of 500m from the bottom of the well.

[0065] During operation, it is necessary to design the volume of various cementing fluids in the oil and gas wellbore, especially the volume of cement slurry required for the annulus in the formation sealing section. Generally, non-cement slurry fluids such as pre-flush fluid and post-flush fluid enter the casing, while the cement slurry remains in the wellbore annulus to seal the formation. If the volume of the wellbore annulus 500m from the bottom of the well is V1, the designed cement slurry volume is V2 = V1 + C, where C is an additional amount, generally 2m³. 3 -3m 3 .

[0066] The following describes a cementing method combining forward and reverse circulation. This method utilizes the aforementioned cementing tool that combines forward and reverse circulation, and includes the following steps:

[0067] Step 1: Preparations before construction;

[0068] The reverse circulation cementing cutoff float 3 receives the excitation target signal on the ground via receiver 3324, and stores the excitation target signal in memory 3325 via control unit 3322;

[0069] Step 2: Lower the cementing tool with the combined forward and reverse circulation into the wellbore;

[0070] Step 3: Inject flushing fluid into the cementing tool with combined forward and reverse circulation;

[0071] Step 4: Sequentially inject signal cement slurry and cementing cement slurry into the combined forward and reverse circulation cementing tool. The signal cement slurry is a mixture of a trigger beacon and cementing cement slurry, and the volume of the signal cement slurry is 0.5 m³. 3 -2m 3 The volume of the cement slurry is equal to the volume of the lowest wellbore annulus 4;

[0072] Step 5: Inject displacement fluid into the cementing tool with combined forward and reverse circulation;

[0073] Step 6: The signal cement slurry flows to the reverse circulation cementing cutoff float 3. The control unit 3322 compares the excitation signal emitted by the excitation beacon with the excitation target signal stored in the memory 3325. The control module 332 controls the cutoff module 333 to close the upper inner flow channel 3312.

[0074] The following section uses a single-stage cementing tool with combined forward and reverse circulation as an example to describe the cementing method with combined forward and reverse circulation in detail. The cementing method with combined forward and reverse circulation includes the following steps in sequence:

[0075] A certain well has a depth of 2000m, a wellbore size of Φ222.2mm, and a casing size of Φ139.7mm. Based on the formation conditions, the well bottom is to be sealed up to 800m above the bottom.

[0076] Step 1: Preparations before construction;

[0077] A single-stage cementing tool combining forward and reverse circulation is designed. A reverse circulation cementing cut-off float 3 is located at the lower end of the tool, and a cross circulation sub 2 is located above the reverse circulation cementing cut-off float 3. The distance between the cross circulation sub 2 and the reverse circulation cementing cut-off float 3 is 800 mm. The cross circulation sub 2 and the reverse circulation cementing cut-off float 3 are connected by a casing 1, with the upper end of the cross circulation sub 2 externally connected to the casing 1. The outer diameters of the cross circulation sub 2, the reverse circulation cementing cut-off float 3, and the casing 1 are all Φ139.7 mm.

[0078] The required amount of working fluid is calculated as shown in Table 1 below.

[0079] Table 1. Working Fluid Usage Table

[0080]

[0081] The reverse circulation cementing cut-off float 3 receives the excitation target signal at the surface via receiver 3324 and stores the excitation target signal in memory 3325 via control unit 3322. The initial state of the one-way valve 32 is closed, and the initial state of the cut-off assembly 33 is open, i.e., the lower inner flow channel 3212 is closed and the upper inner flow channel 3312 is open. The cementing tool combining forward and reverse circulation receives the excitation target signal at the surface via receiver 3324 and stores it in memory 3325 via control unit 3322. The baffles 3333 are all located inside the upper cylinder wall 3311, the second spring 3332 is in a compressed state, the magnetic stop pin 3328 is inserted into the baffles 3333, and the magnetic stop pin 3328 can prevent the baffles 3333 from moving along the diameter direction of the outer shell 31. The third spring 3334 is normally in a free state.

[0082] Combined to form the single-stage positive and negative circulation cementing tool;

[0083] Step 2: Lower the single-stage forward and reverse circulation cementing tool into the wellbore and circulate the drilling fluid;

[0084] Step 3: Pressure test the construction pipeline at 25 MPa, stabilize the pressure for 5 minutes and observe for any pressure drop. If no pressure drop is found, release the pressure. Inject flushing fluid into the single-stage forward and reverse circulation cementing tool. The volume of the flushing fluid is 12.5 m³. 3 The injection flow rate of the flushing fluid is 1m. 3 / min;

[0085] Step 4: Sequentially inject signal cement slurry and cementing cement slurry into the single-stage forward and reverse circulation combined cementing tool. The signal cement slurry is a mixture of a certain amount of trigger beacon and cementing cement slurry (i.e., the cement slurry in Table 1 above), and the volume of the signal cement slurry is 0.5 m³. 3 -2m3 The injection flow rate of the signal cement slurry is 1m. 3 / min, the volume of the cementing slurry (i.e., the cement slurry in Table 1 above) is equal to the volume of the lowest wellbore annulus 4, and the volume of the cementing slurry is 19m³. 3 The injection flow rate of the cement slurry is 1m. 3 / min;

[0086] Step 5: Inject displacement fluid into the single-stage forward and reverse circulation cementing tool. The volume of the displacement fluid is 18.5 m³. 3 The injection flow rate of the displacement fluid is 1 m. 3 / min;

[0087] Step 6: The signal cement slurry flows to the reverse circulation cementing cut-off float 3. The cementing slurry enters from the lower end of the outer shell 31 and then exits from the upper end of the outer shell 31. The cementing slurry flows through the lower inner flow channel 3212 of the one-way valve 32 and the upper inner flow channel 3312 of the cut-off assembly 33. Signal detector 3321 transmits the real-time detection signal inside the casing (i.e., the upper inner flow channel 3312) to control unit 3322 for real-time comparison with the target signal stored in memory 3325. Control unit 3322 verifies that the excitation signal emitted by the excitation beacon matches the excitation target signal stored in memory 3325. Control unit 3322 then sends a control command to execution unit 3323, energizing electromagnetic actuator 3327. Magnetic stop pin 3328 moves upward and disengages from baffle 3333. Second spring 3332 causes baffle 3333 to enter the upper inner flow channel 3312, and baffle 3333 matches and inserts into baffle slot 3331, thereby closing the upper inner flow channel 3312. At this time, the flow-stopping component 33 is in the closed state, i.e., the upper inner flow channel 3312 is also closed. Then, check valve 32 also returns to the closed state. At this time, the cementing pump injection equipment construction pressure suddenly rises to 25MPa, and operation stops.

[0088] After cementing operations are completed, the fluid distribution within the oil and gas wellbore is as follows: Figure 11 As shown, the wellbore contains, from bottom to top, a first wellbore annulus section 101, a first casing internal cavity section 102, a second wellbore annulus section 103, and a second casing internal cavity section 104. Cement slurry is only located in the first wellbore annulus section 101, that is, only the first wellbore annulus section 101 is a cement slurry region 108, and the rest are non-cement slurry regions 107.

[0089] The following section uses a cementing tool combining forward and reverse circulation as an example of a two-stage forward and reverse circulation cementing tool to describe the cementing method combining forward and reverse circulation in detail. The cementing method combining forward and reverse circulation includes the following steps in sequence:

[0090] A certain well has a depth of 4000m, a wellbore size of Φ222.2mm, and a casing size of Φ139.7mm. Based on the formation conditions, two formation sections are selected for sealing: 0m-800m and 1200m-1800m at the bottom of the well.

[0091] Step 1: Preparations before construction;

[0092] The design incorporates a dual-stage forward and reverse circulation cementing tool, employing a reverse circulation cementing cut-off float 3 and three cross circulation subs 2. The reverse circulation cementing cut-off float 3 is located at the lower end of the dual-stage forward and reverse circulation cementing tool, while the three cross circulation subs 2 are positioned above the reverse circulation cementing cut-off float 3. The three cross circulation subs 2 are arranged at intervals along the vertical direction. The distance between the lowermost cross circulation sub 2 and the reverse circulation cementing cut-off float 3 is 800m, the distance between the lowermost cross circulation sub 2 and the middle cross circulation sub 2 is 400m, and the distance between the uppermost cross circulation sub 2 and the middle cross circulation sub 2 is 600m. The cross circulation subs 2 are connected to each other via a casing 1, and the cross circulation sub 2 is connected to the reverse circulation cementing cut-off float 3 via a casing 1. The upper end of the uppermost cross circulation sub 2 is externally connected to the casing 1. The outer diameter of the cross circulation sub 2, the outer diameter of the reverse circulation cementing cutoff float 3, and the outer diameter of the casing 1 are all Φ139.7mm.

[0093] The required amount of working fluid is calculated as shown in Table 2 below.

[0094] Table 2. Working Fluid Usage Table

[0095]

[0096] The reverse circulation cementing cut-off float 3 receives the excitation target signal at the surface via receiver 3324 and stores the excitation target signal in memory 3325 via control unit 3322. The initial state of the one-way valve 32 is closed, and the initial state of the cut-off assembly 33 is open, i.e., the lower inner flow channel 3212 is closed and the upper inner flow channel 3312 is open. The cementing tool combining forward and reverse circulation receives the excitation target signal at the surface via receiver 3324 and stores it in memory 3325 via control unit 3322. The baffles 3333 are all located inside the upper cylinder wall 3311, the second spring 3332 is in a compressed state, the magnetic stop pin 3328 is inserted into the baffles 3333, and the magnetic stop pin 3328 can prevent the baffles 3333 from moving along the diameter direction of the outer shell 31. The third spring 3334 is normally in a free state.

[0097] This allows for the combination of a two-stage positive and negative circulation cementing tool.

[0098] Step 2: Lower the cementing tool with the dual-stage forward and reverse circulation combination into the wellbore and circulate the drilling fluid;

[0099] Step 3: Pressure test the construction pipeline at 25 MPa, stabilize the pressure for 5 minutes and observe for any pressure drop. If no pressure drop is found, release the pressure. Inject flushing fluid into the single-stage forward and reverse circulation cementing tool. The volume of the flushing fluid is 12.5 m³. 3 The injection flow rate of the flushing fluid is 1m. 3 / min;

[0100] Step 4: Sequentially inject signal cement slurry and cementing cement slurry into the dual-stage forward and reverse circulation cementing tool. The signal cement slurry is a mixture of a certain amount of trigger beacon and cementing cement slurry (i.e., the cement slurry in Table 1 above), and the volume of the signal cement slurry is 0.5 m³. 3 -2m 3 The injection flow rate of the signal cement slurry is 1m. 3 / min, the volume of the cementing slurry (i.e., the cement slurry in Table 1 above) is equal to the volume of the lowest wellbore annulus 4, and the volume of the cementing slurry is 19m³. 3 The injection flow rate of the cement slurry is 1m. 3 / min, the density of both signal cement slurry and cementing cement slurry is 1.40 g / cm³. 3 ;

[0101] Step 5: Inject displacement fluid into the dual-stage forward and reverse circulation cementing tool. The volume of the displacement fluid is equal to the sum of the volumes of the second annulus section 103, the second casing internal cavity section 104, the third annulus section 105, and the third casing internal cavity section 106, counting from bottom to top within the wellbore. For example, the volume of the displacement fluid is 6 m³. 3 The injection flow rate of the displacement fluid is 1 m. 3 / min;

[0102] Then, cement slurry is injected into the cementing tool with the combined two-stage forward and reverse circulation. The volume of the cement slurry is equal to the volume of the third annulus section 105 in the wellbore counting from the bottom up. For example, the volume of the cement slurry is 14 m³. 3 The cement grout injection velocity is 1m. 3 / min;

[0103] Then, displacement fluid is injected into the cementing tool with a combined two-stage forward and reverse circulation, and the volume of the displacement fluid is 34m³. 3 The injection flow rate of the displacement fluid is 1 m. 3 / min;

[0104] Step 6: The signal cement slurry flows to the reverse circulation cementing cut-off float 3. The cementing slurry enters from the lower end of the outer shell 31 and then exits from the upper end of the outer shell 31. The cementing slurry flows through the lower inner flow channel 3212 of the one-way valve 32 and the upper inner flow channel 3312 of the cut-off assembly 33. Signal detector 3321 transmits the real-time detection signal inside the casing (i.e., the upper inner flow channel 3312) to control unit 3322 for real-time comparison with the target signal stored in memory 3325. Control unit 3322 verifies that the excitation signal emitted by the excitation beacon matches the excitation target signal stored in memory 3325. Control unit 3322 then sends a control command to execution unit 3323, energizing electromagnetic actuator 3327. Magnetic stop pin 3328 moves upward and disengages from baffle 3333. Second spring 3332 causes baffle 3333 to enter the upper inner flow channel 3312, and baffle 3333 matches and inserts into baffle slot 3331, thereby closing the upper inner flow channel 3312. At this time, the flow-stopping component 33 is in the closed state, i.e., the upper inner flow channel 3312 is also closed. Then, check valve 32 also returns to the closed state. At this time, the cementing pump injection equipment construction pressure suddenly rises to 35MPa, and operation stops.

[0105] After cementing operations are completed, the fluid distribution within the oil and gas wellbore is as follows: Figure 12 As shown, the wellbore contains, from bottom to top, a first wellbore annulus 101, a first casing internal cavity 102, a second wellbore annulus 103, a second casing internal cavity 104, a third wellbore annulus 105, and a third casing internal cavity 106. Cement slurry is only located in the first wellbore annulus 101 and the third wellbore annulus 105, that is, only the first wellbore annulus 101 and the third wellbore annulus 105 are cement slurry regions 108, and the rest are non-cement slurry regions 107.

[0106] The combined forward and reverse circulation cementing method fully utilizes the advantages of both forward and reverse circulation cementing processes. It achieves pressure balance and cement slurry delivery, and solves the problems of cementing in ultra-long cementing sections and complex formations. It greatly improves cementing quality and construction efficiency, and is suitable for cementing operations in oil and gas wells under complex geological conditions.

[0107] The aforementioned cementing method combining forward and reverse circulation can reduce the amount of cement slurry used and the pollution to the formation by selecting unstable formation sections for cementing instead of the entire oil and gas wellbore, thus better reflecting environmental friendliness and cost control. Furthermore, the cross-circulation sub 2 and the reverse circulation cementing cut-off float 3 used do not affect the drilling fluid circulation after casing is installed.

[0108] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of protection of the present invention, should still fall within the scope of the present invention. Furthermore, the technical features, technical features and technical solutions, and technical solutions in the present invention can be freely combined and used.

Claims

1. A cementing tool combining forward and reverse circulation, characterized in that, The cementing tool combining forward and reverse circulation includes a cross-circulation short section (2) and a reverse circulation cementing cutoff float (3) arranged vertically. The reverse circulation cementing cutoff float (3) includes an outer shell (31), which is an upright cylindrical structure. The outer shell (31) contains a shell wall (311) and an internal flow channel (312). The internal flow channel (312) contains a cutoff assembly (33) arranged vertically and a one-way valve (32). The cutoff assembly (33) contains an upper shell (331), which is also an upright cylindrical structure. The upper shell (331) contains an upper cylindrical wall (3311) and an upper inner flow channel (3312). The upper cylindrical wall (3311) contains a control module (332) and a cutoff module (333). The control module (332) can control the cutoff module (333) to close the upper inner flow channel (3312).

2. The cementing tool with combined forward and reverse circulation according to claim 1, characterized in that, The cross-circulation sub (2) enables the wellbore annulus (4) above the cross-circulation sub (2) to be disconnected from the wellbore annulus (4) below the cross-circulation sub (2). The cross-circulation sub (2) contains a first channel (25) and a second channel (26). The first channel (25) enables the casing cavity (5) above the cross-circulation sub (2) to be connected to the wellbore annulus (4) below the cross-circulation sub (2). The second channel (26) enables the casing cavity (5) below the cross-circulation sub (2) to be connected to the wellbore annulus (4) above the cross-circulation sub (2).

3. The cementing tool with combined forward and reverse circulation according to claim 2, characterized in that, The cross-circulation sub (2) contains an inner section (23) and a sealing structure (24) with inner and outer sleeves. The upper end of the inner section (23) is provided with an upper connector section (21), and the lower end of the inner section (23) is provided with a lower connector section (22). The sealing structure (24) can be sealed to the well wall (6). The inner section (23) is an upright cylindrical structure. The upper end of the first channel (25) is located on the upper surface of the inner section (23), and the lower end of the first channel (25) is located on the side circumferential surface of the inner section (23). The lower end of the first channel (25) is lower than the sealing structure (24). The upper end of the second channel (26) is located on the side circumferential surface of the inner section (23), and the upper end of the second channel (26) is higher than the sealing structure (24). The lower end of the second channel (26) is located on the lower surface of the inner section (23).

4. The cementing tool with combined forward and reverse circulation according to claim 1, characterized in that, An annular inner cavity (3313) is provided inside the upper cylinder wall (3311). The control module (332) and the flow-blocking module (333) are both located inside the annular inner cavity (3313). The upper inner flow channel (3312) runs through the upper shell (331) along the axial direction of the upper shell (331). The control module (332) contains a signal detector (3321), a control unit (3322), and an execution unit (3323) connected in sequence. The control unit (3322) is connected to a memory (3325). The signal detector (3321) can send real-time detection signals to the control unit (3322). The control unit (3322) compares the real-time detection signals with the target signals stored in the memory (3325) in real time. When the real-time detection signals are consistent with the target signals, the control unit (3322) controls the flow-blocking module (333) to close the upper inner flow channel (3312) through the execution unit (3323).

5. The cementing tool with combined forward and reverse circulation according to claim 4, characterized in that, The control unit (3322) is also connected to a receiver (3324) and a power supply (3326). The control unit (3322) can receive the target signal through the receiver (3324) and store it in the memory (3325). The execution unit (3323) contains an electromagnetic actuator (3327) and a magnetic stop (3328). The electromagnetic actuator (3327) can move the magnetic stop (3328) toward the electromagnetic actuator (3327).

6. The cementing tool with combined forward and reverse circulation according to claim 5, characterized in that, The flow interception module (333) contains a baffle (3333) and a second spring (3332) connected in sequence. The baffle (3333) is perpendicular to the axis of the upper shell (331). When the upper inner flow channel (3312) is in the open state, the baffle (3333) is completely located inside the upper cylinder wall (3311), the second spring (3332) is in the compressed state, and the magnetic stop pin (3328) is inserted into the baffle (3333). The magnetic stop pin (3328) can prevent the baffle (3333) from moving along the diameter direction of the upper shell (331).

7. The cementing tool with combined forward and reverse circulation according to claim 6, characterized in that, One end of the second spring (3332) is connected to one end of the baffle (3333). The electromagnetic actuator (3327) can cause the magnetic stop pin (3328) to disengage from the baffle (3333). The second spring (3332) can cause the baffle (3333) to enter the upper inner flow channel (3312) and close the upper inner flow channel (3312).

8. The cementing tool with combined forward and reverse circulation according to claim 7, characterized in that, The upper cylinder wall (3311) includes an outer peripheral wall (3314) and an inner peripheral wall (3315). The other end of the second spring (3332) is connected to the outer peripheral wall (3314). The upper cylinder wall (3311) contains a baffle slide (3335). The extension direction of the baffle slide (3335) is perpendicular to the axis of the upper shell (331). The baffle (3333) is matched and connected with the baffle slide (3335). The baffle (3333) can slide along the baffle slide (3335). The inner surface of the inner peripheral wall (3315) contains a baffle groove (3331). When the baffle (3333) closes the upper inner flow channel (3312), the other end of the baffle (3333) is matched and inserted into the baffle groove (3331).

9. The cementing tool with combined forward and reverse circulation according to claim 1, characterized in that, The reverse circulation cementing cutoff float (3) is located at the lower end of the cementing tool that combines forward and reverse circulation. The cementing tool that combines forward and reverse circulation includes multiple cross circulation short sections (2), which are arranged in the vertical direction. Two adjacent cross circulation short sections (2) are connected by a casing (1), and the cross circulation short sections (2) and the reverse circulation cementing cutoff float (3) are connected by a casing (1).

10. A cementing method combining forward and reverse circulation, characterized in that, The cementing method combining forward and reverse circulation employs the cementing tool combining forward and reverse circulation as described in claim 1, and the cementing method combining forward and reverse circulation includes the following steps in sequence: Step 1: Preparations before construction; The reverse circulation cementing cutoff float (3) receives the excitation target signal on the ground through the receiver (3324), and stores the excitation target signal in the memory (3325) through the control unit (3322); Step 2: Insert the cementing tool with the combined forward and reverse circulation into the wellbore; Step 3: Inject flushing fluid into the cementing tool with combined forward and reverse circulation; Step 4: Sequentially inject signal cement slurry and cementing cement slurry into the combined forward and reverse circulation cementing tool. The signal cement slurry is a mixture of a trigger beacon and cement slurry, and the volume of the signal cement slurry is 0.5 m³. 3 -2m 3 The volume of the cement slurry is equal to the volume of the bottommost wellbore annulus (4); Step 5: Inject displacement fluid into the cementing tool with combined forward and reverse circulation; Step 6: The signal cement slurry flows to the reverse circulation cementing cutoff float (3). The control unit (3322) compares the excitation signal emitted by the excitation beacon with the excitation target signal stored in the memory (3325). The control module (332) controls the cutoff module (333) to close the upper inner flow channel (3312).

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