Well cementation method and well cementation system suitable for surface casing interpolation method
By installing a cementing system with floating hoops and floating shoes on the bottom of the surface casing, the problems of mixing, uneven injection and difficult to control the length of the cement in the interpolation method are solved, and high-quality cementing and easy operation are achieved. Effect.
Patent Information
- Application Number
- CN202411527432.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-30
- Publication Date
- 2025-02-07
AI Technical Summary
The existing interpolation cementing technology has problems such as mixing in casing, uneven injection of cement slurry, failure to replace cement slurry in drill rod strings, and difficult to control the length of cement plugs.
A cementing system is adopted to install floating hoops and floating shoes on the bottom of the surface casing. The fluid is sealed into the socket of the floating hoop through a drill string to avoid slurry and control the length of the cement plug through a check valve.
It effectively avoids the slurry mixing problem in the casing, ensures uniform injection of cement slurry and high-quality cementing, simplifies operation and reduces production and equipment costs.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of cementing in petroleum drilling engineering, and in particular to a cementing method and a cementing system suitable for a surface casing insertion method. Background Art
[0002] In oil drilling projects, cementing is the process of running casing into the open hole after each well is drilled to the medium completion depth, and injecting cement into the annulus between the casing and the formation wellbore to seal the well section between the casing and the formation open hole, so as to achieve the purpose of sealing the loose strata on the upper part that are prone to leakage and collapse, and provide wellbore protection conditions for continued drilling or oil and gas development in the lower deep strata.
[0003] During the surface casing cementing construction, due to the large size of the surface casing, it is easy to cause slurry mixing in the pipe during cementing, which will pollute the drilling fluid and cement slurry properties. Therefore, an insertion method of cementing, also known as "internal pipe cementing", is derived. This method is to install a socket at the bottom of the casing when the surface casing is lowered, and then use the drill pipe as the inner pipe, and insert the plug at the bottom of the inner pipe into the socket. During cementing, all fluids are injected through the inner pipe, and then flow through the socket at the bottom of the casing into the annulus.
[0004] At present, there is no systematic description of "interpolation cementing". At the same time, the existing interpolation technology still has the following technical problems: 1) The problem of slurry mixing in the casing cannot be avoided well, and the cement slurry mixes with the original drilling fluid, causing drilling fluid pollution; 2) The cement slurry is injected into the formation unevenly, resulting in poor cementing quality; 3) After the cement slurry is poured to fill the annulus, the cement slurry in the drill pipe string is not replaced in time, blocking the drill pipe water hole; 4) It is difficult to control the length of the cement plug. Summary of the invention
[0005] The purpose of the present invention is to solve the above technical problems and provide a cementing system suitable for surface casing insertion method which has simple system, is easy to operate, and has low production cost and equipment cost.
[0006] The present invention also provides a cementing method suitable for surface casing insertion method using the system, which can control the length of cement plug, avoid slurry mixing and has good cementing quality.
[0007] The present invention is applicable to a cementing system of a surface casing insertion method, comprising an underground part and an above-ground part, wherein the underground part comprises a conduit inserted into a well wall formation and a surface casing string inserted into the well, wherein a float collar and a float shoe are provided at the lower section of the surface casing string, wherein a socket is provided at the center of the float collar, wherein the float shoe is provided with a one-way valve, wherein the upper end of the conduit is connected to a circulation interface, wherein a drill pipe string is provided in the surface casing string, wherein a plug at the lower end of the drill pipe string is correspondingly and sealably plugged into the socket of the float collar;
[0008] The above-ground part comprises a cement supply system and a drilling fluid circulation system, the outlets of the cement supply system and the drilling fluid circulation system are connected to the upper end interface of the drill pipe string, and the inlet of the drilling fluid circulation system is connected to the circulation interface.
[0009] The surface casing string of the underground part is lowered into a depth that is less than 2-3 m of the formation depth.
[0010] The guide tube is lowered into the formation at a depth of 90-110 m, and the upper end of the guide tube is flush with the wellbore.
[0011] A one-way valve is arranged at the socket at the center of the floating collar.
[0012] The drilling fluid circulation system includes a solid control device, a storage tank and a power device connected in sequence. The circulation interface is connected to the inlet of the solid control device via a return pipe, and the outlet of the power device is connected to the upper end interface of the drill pipe string via a water supply pipe and a grouting pipeline of the drilling platform.
[0013] The drilling fluid circulation system also includes an emergency pool, and the return water pipe is also connected to the emergency pool.
[0014] A cementing method suitable for surface casing insertion method comprises the following steps:
[0015] 1) Install a circulation interface at the upper end of the conduit in the well wall formation;
[0016] 2) lowering the surface casing string into the well bottom, at which point the float shoe is located at the bottom of the lower surface casing string and the float collar is located above the float shoe;
[0017] 3) lowering the drill pipe string so that the plug at the lower end of the drill pipe string is correspondingly and sealedly plugged into the socket of the floating collar;
[0018] 4) The drilling fluid is pumped in through the upper end interface of the drill pipe string. Under the action of pressure, it flows out through the internal space of the drill pipe string through the socket of the float collar and pushes open the one-way valve of the float shoe to enter the formation, and then flows through the annulus between the surface casing string and the well wall, and finally flows out from the circulation interface;
[0019] 5) When the drilling fluid starts to flow out of the circulation interface stably, replace the drilling fluid with cement slurry and pump it in through the upper end interface of the drill pipe string until the circulation interface starts to return cement slurry stably;
[0020] 6) Pump the drilling fluid again through the upper end interface of the drill pipe string to replace the cement slurry in the drill pipe string. The amount pumped in is the internal volume of the drill pipe string. Finally, dismantle the pipeline, pull out the pipe string, dismantle the circulation interface and wait for solidification.
[0021] In the step 4), the drilling fluid from the drilling fluid circulation system is pumped in through the upper end interface of the drill pipe string, and the drilling fluid flowing out of the circulation interface is returned to the drilling fluid circulation system.
[0022] In the step 4), the drilling fluid circulation system includes a solid control device, a storage tank and a power device connected in sequence; the drilling fluid flowing out of the circulation interface is removed by the solid control device, flows to the storage tank for collection, and then is pressurized by the power device and pumped into the upper end interface of the drill pipe string.
[0023] In the step 4), the drilling fluid circulation system also includes an emergency tank. When the mixed slurry or cement slurry flows out of the circulation interface, it is switched to be recovered to the emergency tank.
[0024] In view of the problems existing in the background technology, the inventor has made the following improvements:
[0025] 1) When the surface casing is lowered, a floating collar with a socket is installed at the bottom of the casing, and then the drill pipe is used as the inner pipe, and the plug at the bottom of the inner pipe is inserted into the socket. During cementing, all fluids are injected through the inner pipe of the drill pipe, and then flow into the annulus through the socket of the floating collar at the bottom of the surface casing string. The key point is that the plug is inserted into the socket of the floating collar to form a good sealing injection process, which effectively avoids the occurrence of slurry mixing problems; a floating shoe is arranged below the floating collar. On the one hand, a one-way valve is used to avoid backflow, and on the other hand, the height of the floating collar can be flexibly controlled to conveniently control the length of the cement plug.
[0026] 2) Before pouring cement slurry, first pump in drilling fluid to establish a stable circulation, and then pump in cement slurry. This can effectively ensure that the cement slurry is fully poured, without bubbles or hollows, and ensure the quality of cementing. In conjunction with the drilling fluid circulation system, the drawn drilling fluid is filtered and impurities are removed before being pumped back to achieve the recycling of drilling fluid, reduce production costs, and be environmentally friendly.
[0027] 3) After the cement slurry injection is completed, the drilling fluid is pumped into the drill pipe string again to replace the cement slurry in the drill pipe string, so that when the drill pipe string is disassembled later, the cement slurry will not mix with the drilling fluid in the well.
[0028] 4) A detachable circulation interface is provided at the upper end of the conduit, which is used to introduce the drilling fluid in the annulus between the surface casing string and the well wall into the drilling fluid circulation system for filtration and impurity removal before reuse; when the cementing operation is completed, the circulation interface can be removed, and the operation is flexible and convenient.
[0029] 5) The method of the present invention is easy to operate, can control the length of the cement plug, avoid slurry mixing, and has good cementing quality; the system of the present invention is simple, easy to operate, and has low production cost and equipment cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 This is a schematic diagram of the process flow of the present invention, and the direction of the arrow indicates the flow direction of the fluid;
[0031] Figure 1In: 1-cement supply system; 1.1-cement tank; 1.2-cement pump; 1.3-cement pipe; 2-drilling fluid circulation system; 2.1-power equipment; 2.2-solid control equipment; 2.3-water pipe; 2.4-return pipe; 2.5-reserve tank; 2.6-emergency pool; 3-drilling platform; 3.1-grouting pipeline; 3.2-cement circulation head; 4-formation; 5-well wall; 6-conduit; 7-surface casing; 8-drill pipe string; 9-circulation interface; 9.1-return grouting port; 10-cement; 11-drilling fluid; 12-socket; 13-floating collar; 14-floating shoe.
[0032] Figure 2 This is a schematic diagram of the structure of a simple circulation device at the wellhead;
[0033] Figure 2 Explanation of the bid numbers: 9-circulation interface; 9.1-return port; 9.2-connection; 9.3-liquid discharge port.
[0034] Figure 3a-3c Schematic diagram of the downhole cement slurry replacement process according to an embodiment of the present invention, wherein: Figure 3a The process of replacing drilling fluid by pumping cement slurry into the formation. Figure 3b To ensure that the cement slurry is pumped into the correct amount, Figure 3c The process of replacing cement slurry in the drill string to pump in drilling fluid;
[0035] Figure 3a-3c In Chinese: 11.1- replaced drilling fluid; 11.2- replaced drilling fluid; 15- pumped cement slurry.
[0036] Figure 4a-4b FIG. 1 is a schematic diagram of the waiting time for removing the circulation interface according to an embodiment of the present invention, wherein Figure 4a This is a schematic diagram of the waiting time before removing the circulation interface. Figure 4b This is a schematic diagram of the waiting period after the circulation interface is removed. DETAILED DESCRIPTION
[0037] The following will be combined with the drawings in the embodiments of the present invention to describe the technical solutions in the embodiments of the present invention in detail and completely. It should be understood that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0038] The cementing system of the present invention comprises an underground part and an above-ground part.
[0039] The underground part includes a conduit 6 inserted into the formation of the well wall 5 and a surface casing string 7 inserted into the well. The lower section of the surface casing string 7 is provided with a float collar 13 and a float shoe 14 below. The center of the float collar 13 is provided with a socket 12, and a one-way valve is provided at the socket 12. The one-way flow top pressure is 0.5-1MPa. The float shoe 14 is provided with a one-way valve, and the one-way flow top pressure is 0.5-1MPa. The float shoe 14 is buckled and connected to the surface casing 7 and placed at the lowest part of the surface casing string. The fluid flowing out of the plug 12 can enter the formation through the float shoe 14, thereby achieving the effect of controlling the cement plug below the float collar 13.
[0040] The upper end of the conduit 6 is detachably connected to the circulation interface 9, and a drill pipe string 8 is provided in the surface casing string 7. The lower end plug of the drill pipe string 8 is sealed and plugged with the socket 12 of the floating collar 13, so that the liquid flows out from the plug 12 through the drill pipe string 8 and then enters the formation 4 through the one-way valve of the float shoe 14, so as to achieve the effect of controlling the cement plug below the floating collar 13; the surface casing string 7 of the underground part is lowered to a depth less than 2-3m deep in the formation 4, so as to reduce the influence of sand settling at the bottom of the wellbore on the circulation channel of the casing string. The conduit 6 is lowered into the formation 4 after the pilot hole is opened in the early stage, and the depth of the conduit 6 into the formation 4 is preferably 90-110m. Cement 10 is used to solidify between the conduit 6 and the formation 4, and the upper end of the conduit 6 is flush with the wellbore.
[0041] See also Figure 2 The upper section of the circulation interface 9 has a return port 9.1 for leading out drilling fluid, the lower section has a discharge port 9.3 for discharging remaining liquid during disassembly, and the lower end is a connection port 9.2 connected to the conduit 6.
[0042] See also Figure 1 The above-ground part includes a cement supply system 1 and a drilling fluid circulation system 2, the outlets of the cement supply system 1 and the drilling fluid circulation system 2 are connected to the upper end interface of the drill pipe string, and the inlet of the drilling fluid circulation system 2 is connected to the return slurry port 9.1 of the circulation interface 9.
[0043] The cement supply system 1 comprises a cement tank 1.1, a cement pump 1.2 and a cement circulation head 3.2. The cement tank 1.1 is filled with cement slurry for cementing. The cement pump 1.2 can provide sufficient pumping pressure to deliver the cement slurry from the cement tank 1.1 to the bottom of the well through the cement circulation head 3.2 and the drill pipe string 8.
[0044] The drilling fluid circulation system 2 includes a solid control device 2.2, a storage tank 2.5 and a power device 2.1 connected in sequence. The circulation interface 9 is connected to the inlet of the solid control device 2.2 via the return pipe 2.4. The outlet of the power device 2.1 is connected to the cement circulation head 3.2 at the upper interface of the drill pipe string 8 via the upper water pipe 2.3 and the grouting pipeline 3.1. The return pipe 2.4 is also connected to the emergency pool 2.6. The solid control device 2.2 can filter the drilling fluid returned by the return pipe 2.4 and return it to the reserve tank 2.5; the power device 2.1 can pump the drilling fluid in the reserve tank 2.5 into the well through the upper water pipe 2.3 and the drill pipe string 8 for circulation; when the return pipe 2.4 returns cement slurry, it is directly recovered to the emergency pool 2.6 by the return pipe.
[0045] A cementing method suitable for surface casing insertion method comprises the following steps:
[0046] 1) installing a circulation interface 9 at the upper end of the conduit 6;
[0047] 2) lowering the surface casing string 7 to the bottom of the well, at which time the float shoe 14 is located at the bottom of the surface casing string 7 and the float collar 13 is located above the float shoe 14;
[0048] 3) lowering the drill pipe string 8 and applying an additional drilling pressure of 3-6t to seal the plug at the lower end of the drill pipe string 8 with the socket 12 of the floating collar 13;
[0049] 4) The drilling fluid is pumped in through the upper end interface (cement circulation head 3.2) of the drill pipe string 8. Under the action of pressure, the drilling fluid flows out through the internal space of the drill pipe string 8 through the socket 12 of the float collar 13 and pushes open the one-way valve of the float shoe 14 to enter the formation, and then flows through the annulus between the surface casing string 7 and the well wall 5, and finally flows out from the circulation interface 9 and is sent back to the drilling fluid circulation system 2;
[0050] The drilling fluid circulation system 2 includes a solid control device 2.2, a storage tank 2.5 and a power device 2.1 connected in sequence; the drilling fluid flowing out of the circulation interface 9 is removed by the solid control device 2.2, flows to the storage tank 2.5 for collection, and then is pressurized by the power device 2.1 and pumped into the upper end interface (cement circulation head 3.2) of the drill pipe string 8 to participate in the circulation.
[0051] 5) When the drilling fluid flows out stably from the circulation interface 9, the drilling fluid is replaced with cement slurry and pumped in through the upper end interface of the drill pipe string until the circulation interface starts to stably return cement slurry and then stops; when the circulation interface 9 flows out of the mixed slurry or cement slurry, the drilling fluid circulation system 2 is switched to be recovered to the emergency tank 2.6;
[0052] 6) Pump drilling fluid again through the upper end interface of the drill pipe string 8 to replace the cement slurry in the drill pipe string 8. The pumped amount is the internal volume of the drill pipe string 8. Finally, dismantle the pipeline (including cement pipe 1.3, water supply pipe 2.3 and return pipe 2.4), pull out the drill pipe string 8, dismantle the circulation interface 9 and wait for solidification for 24-48 hours.
[0053] Example:
[0054] Step 1: Confirm the well depth and diameter based on the preliminary pilot hole construction and the first drilling data.
[0055] In the early stage, the conduit 6 is put into place for cementing, and the next stage of construction begins after the cement 10 solidifies. The dimensions of the conduit 6 are shown in Table 1.
[0056] Table 1, Catheter Dimensions
[0057]
[0058] The well was drilled to a depth of 1500m using a 444.5mm drill bit. The expansion rate of wellbore 5 was calculated as 15%, as shown in Table 2.
[0059] Table 2, drill bit sizes
[0060]
[0061] Step 2: Calculate the amount of cement slurry required for cementing according to the depth of the surface casing 7, and the positions of the float collar 13 and the float shoe 14. Ensure that the amount of drilling fluid stored in the reserve tank is sufficient, and the total volume is greater than 1.5V0; calculate the closed volume V1 and content V2 of the casing string according to the size and depth of the casing string; determine the length of the drill pipe string according to the position of the float collar, and determine the closed volume V3 and content V4 of the drill pipe string; calculate the required volume of cement slurry according to the position of the float collar in the casing string, cement slurry volume V5 = volume between the float collar and the float shoe + annulus volume between the casing string and the wellbore, the cement tank should reserve at least 1.3V5 cement slurry, or have the ability to configure 1.3V5 cement slurry while meeting the flow demand;
[0062] The lower surface casing 7 is to a well depth of 1498 m, the float shoe 14 is located at the bottom of the casing string 7, and the float collar 13 is located 50 m away from the bottom of the casing string 7, as shown in Table 3.
[0063] Table 3, Casing Dimensions
[0064]
[0065] According to the position of the floating collar in Table 3, the depth of the drill pipe string 8 can be confirmed. When a drill pipe with a size of Φ139.7x10.54mm is used, the volume of the drill pipe string can be confirmed, as shown in Table 4.
[0066] Table 4, Drill string dimensions
[0067]
[0068] According to the above data, it can be calculated that the annular volume of the overlapping section (0-100m) between the guide tube 6 and the surface casing 7 is 94.63L / m, and the annular volume between the surface casing 7 and the well wall 5 is 114.53L / m; the unit content of the surface casing 7 is 78.05L / m, and then the amount of cement slurry required for the cement truck group 1 is determined, as shown in Table 5.
[0069] Table 5, cement slurry dosage
[0070]
[0071] Step 3: Lower the drill string 8 and ensure that the plug 12 is sealed.
[0072] After the surface casing string 7 is in place, the drill pipe string 8 is lowered. The bottom end of the drill pipe string 8 is connected to the plug 12 until the plug 12 is drilled down to the position of the float collar 13 (corresponding to a well depth of 1448m). Then, an additional drilling pressure of 3-6t is applied to ensure that the plug 12 is inserted into the float collar 13 and forms a seal.
[0073] Step 4: Connect the cement circulation head 3.2, confirm the pipeline valve opening, circulate the drilling fluid, and start pumping in cement slurry. The process flow is as follows: Figure 1 shown.
[0074] Start the power equipment 2.1 of the drilling fluid tank area 2, and the drilling fluid in the reserve tank 2.5 flows from the upper water pipe 2.3 through the grouting pipeline 3.1 and the cement circulation head 3.2 into the water hole of the drill pipe string 8, flows out from the return plug 12, pushes the float shoe 14 to enter the formation 4, and then flows through the annulus between the casing string 7 and the formation 5 and flows out from the return slurry port 9.1 of the simple circulation head 9, and returns to the drilling fluid tank area 2 through the return pipe 2.4. The drilling fluid treated by the solid control equipment 2.2 flows back to the reserve tank 2.5 to continue to participate in the circulation.
[0075] Step 4: When the drilling fluid is circulated until the outlet flow and pump pressure are stable, prepare to pump cement slurry into the cement supply system 1
[0076] The power equipment 2.1 of the drilling fluid tank area 2 is stopped, and the cement supply system 1 is operated. The cement pump 1.2 starts to pump the cement slurry in the cement tank 1.1, flows into the drill pipe string 8 through the cement circulation head 3.2, flows out at the outlet of the return plug 12, pushes open the float shoe 14, and enters the formation 4. The drilling fluid in the formation 4 is returned through the return slurry port 9.1 of the wellhead circulation interface 9, and is processed by the solid control equipment 2.2 through the return water pipe 2.4 and recovered to the storage tank 2.5.
[0077] During the process of pumping cement slurry, cement slurry continuously enters the formation and replaces the drilling fluid in the formation. Figure 3a As shown;
[0078] The cement slurry pumping process is well measured. Theoretically, when the cement slurry pumped into the formation 5 reaches the calculated amount of 173.5m 3 When the cement slurry is flowing out of the return port 9.1, observe whether the cement slurry begins to flow out. At this time, the outlet of the return pipe 2.4 is connected to the emergency pool 2.6 to promptly recycle the returned cement slurry to the emergency pool 2.6;
[0079] Continue pumping cement slurry for 5-10m 3 When the cement slurry returned from the return port 9.1 is stable and continuous, the cement pump 1.2 of the cement supply system 1 is stopped, and the power equipment 2.1 of the drilling fluid tank area 2 is started to pump the drilling fluid into the reserve tank 2.5 to replace the cement slurry in the drill pipe string 8. Figure 3b shown.
[0080] Theoretically, the calculated amount of drilling fluid pumped into the drill string 8 is 16m 3 When (see Table 4), all cement slurry in the drill string is replaced, and the returned cement slurry is collected and put into the emergency pool 2.6, and an additional 1m 3 , ensure that all cement slurry in the drill string 8 is replaced, such as Figure 3c shown.
[0081] Step 5: Dismantle the pipeline, remove the pipe string and wait for solidification
[0082] After replacing the drilling fluid to a certain amount, stop the power device 2.1, verify that there is no backflow from the water hole of the drill pipe string 8, then disassemble the cement pipe 1.3, the grouting pipeline 3.1 and the cement circulation head 3.2, and pull out the drill pipe string 8. Figure 4a As shown; after draining the excess cement slurry through the 9.3 drain port, remove the circulation interface 9 and wait for 24-48 hours. Figure 4b As shown, cementing is completed with good cementing effect and no slurry mixing problem occurs.
[0083] Although the preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A cementing system suitable for surface casing insertion method, comprising an underground part and an above-ground part, characterized in that: The underground part includes a conduit inserted into the well wall formation and a surface casing string inserted into the well, a float collar and a float shoe are provided at the lower section of the surface casing string, a socket is provided at the center of the float collar, and a one-way valve is provided on the float shoe, the upper end of the conduit is connected to a circulation interface, a drill pipe string is provided in the surface casing string, and a plug at the lower end of the drill pipe string is sealed and plugged correspondingly to the socket of the float collar; The above-ground part comprises a cement supply system and a drilling fluid circulation system, the outlets of the cement supply system and the drilling fluid circulation system are connected to the upper end interface of the drill pipe string, and the inlet of the drilling fluid circulation system is connected to the circulation interface.
2. The cementing system suitable for surface casing insertion method according to claim 1, characterized in that: The surface casing string of the underground part is lowered to a depth less than 2-3 m of the formation depth.
3. The cementing system suitable for surface casing insertion method according to claim 1 or 2, characterized in that: The guide tube is lowered into the formation at a depth of 90-110 m, and the upper end of the guide tube is flush with the wellbore.
4. The cementing system suitable for surface casing insertion method according to claim 1 or 2, characterized in that: A one-way valve is arranged at the socket at the center of the floating collar.
5. The cementing system suitable for surface casing insertion method according to claim 1, characterized in that: The drilling fluid circulation system includes a solid control device, a storage tank and a power device connected in sequence. The circulation interface is connected to the inlet of the solid control device via a return pipe, and the outlet of the power device is connected to the upper end interface of the drill pipe string via a water supply pipe and a grouting pipeline of the drilling platform.
6. The cementing system suitable for surface casing insertion method according to claim 5, characterized in that: The drilling fluid circulation system also includes an emergency pool, and the return water pipe is also connected to the emergency pool.
7. A cementing method suitable for surface casing insertion method, characterized in that: The following steps are involved: 1) Install a circulation interface at the upper end of the conduit in the well wall formation; 2) lowering the surface casing string into the well bottom, at which point the float shoe is located at the bottom of the lower surface casing string and the float collar is located above the float shoe; 3) lowering the drill pipe string so that the plug at the lower end of the drill pipe string is correspondingly and sealedly plugged into the socket of the floating collar; 4) The drilling fluid is pumped in through the upper end interface of the drill pipe string. Under the action of pressure, it flows out through the internal space of the drill pipe string through the socket of the float collar and pushes open the one-way valve of the float shoe to enter the formation, and then flows through the annulus between the surface casing string and the well wall, and finally flows out from the circulation interface; 5) When the drilling fluid starts to flow out of the circulation interface stably, replace the drilling fluid with cement slurry and pump it in through the upper end interface of the drill pipe string until the circulation interface starts to return cement slurry stably; 6) Pump the drilling fluid again through the upper end interface of the drill pipe string to replace the cement slurry in the drill pipe string. The amount pumped in is the internal volume of the drill pipe string. Finally, disassemble the pipeline, pull out the pipe string, disassemble the circulation interface, and wait for solidification.
8. The cementing method applicable to the surface casing insertion method as claimed in claim 7, characterized in that: In the step 4), the drilling fluid from the drilling fluid circulation system is pumped in through the upper end interface of the drill pipe string, and the drilling fluid flowing out of the circulation interface is returned to the drilling fluid circulation system.
9. The cementing method applicable to the surface casing insertion method as claimed in claim 8, characterized in that: In the step 4), the drilling fluid circulation system includes a solid control device, a storage tank and a power device connected in sequence; the drilling fluid flowing out of the circulation interface is removed by the solid control device, flows to the storage tank for collection, and then is pressurized by the power device and pumped into the upper end interface of the drill pipe string.
10. The cementing method applicable to the surface casing insertion method according to claim 9, characterized in that: In the step 4), the drilling fluid circulation system also includes an emergency tank. When the mixed slurry or cement slurry flows out of the circulation interface, it is switched to be recovered to the emergency tank.