Pipe fixing method under the condition of total loss of drilling fluid in the deflection section of surface directional drilling technology

Abstract

The application provides a pipe fixing method under full loss of a directional drilling fluid in a build-up section, and belongs to the field of drilling engineering. The pipe fixing method is used in directional construction of a second opening build-up section in a ground area treatment engineering construction process. When a target layer is entered and a design position is reached, full loss of the drilling fluid suddenly occurs. A bottom structure of a casing is improved, and a slurry leakage hole is processed, so that the pipe is fixed under the full loss condition, and a method capable of meeting design requirements is achieved. The method successfully solves the problems of high difficulty of pipe fixing operation under the full loss condition and high return of sealing cement, which cannot reach an ideal position. Meanwhile, the method avoids the threat of the conventional method of first sealing and then fixing the pipe, which cannot guarantee the safety of the open hole section, and causes the hole to be abandoned due to hole sweeping and a new hole. The application has high reliability and high success rate, and can well solve the problem of rapid pipe fixing under the full loss of the drilling fluid.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling engineering, and more specifically, relates to a pipe fixing method under the condition of total loss of drilling fluid in the deflection section of a ground directional technology. Background Art

[0002] When there is a highly pressurized, water-rich or extremely strong aquifer in the coal seam floor, the surface water hazard regional control method is currently usually adopted to carry out local grouting transformation of the aquifer, transforming the original aquifer into a relatively impermeable layer or sealing the original water-conducting (water-bearing) fissures, so that the coal seam mining is no longer threatened by the water of the pressurized aquifer, so as to ensure the safety of mine water prevention and control. In the North China coalfield area, the surface regional control project generally focuses on grouting the top of the thin layer of limestone or thick layer of limestone in the bottom of the mined coal seam. The top of the thin layer of limestone or thick layer of limestone is selected as the target layer, but before entering the selected target layer, the drilling must pass through multiple goafs and other aquifers. In order to ensure that the slurry can enter the target layer normally, the upper goaf and impermeable layer need to be isolated to achieve the purpose of grouting treatment of the target layer. Generally, a through pipe is lowered to directly enter the target layer to directly transport the slurry. However, years of engineering experience have shown that when drilling into the target formation, due to the high degree of karst fissures in the target formation, drilling fluid loss is very common. In some cases, even complete loss of drilling fluid occurs, resulting in a lost return. When complete drilling fluid loss occurs, the hole wall cannot be secured due to the lack of drilling fluid wall protection. This can easily lead to hole collapse or block loss, resulting in in-hole accidents. The conventional approach in such situations is to immediately pull out the drill, then grout the original hole, and then perform a sweep after the grout has fully solidified to resolve the loss. This conventional approach presents a number of problems. First, direct grouting can easily collapse the hole wall in the open hole, making it difficult to ensure the quality of the bottom hole seal and increasing the difficulty of the operation. Second, the sealing section is redundant, resulting in wasteful work and a delay in the construction schedule. Third, sweeping the hole after the grout has solidified can easily create a new hole, making it impossible to ensure that the hole remains on the original trajectory. Therefore, a simple and efficient method is needed to address these issues. By processing and modifying the casing and combining it with on-site construction methods, in the event of complete loss of drilling fluid, it is possible to ensure in-hole construction safety and meet design requirements while saving costs and construction time. Summary of the Invention

[0003] The present invention aims to provide a method for securing pipe in the buildup section of a surface directional drilling technique under conditions of complete fluid loss. When the buildup section of a surface directional drilling technique reaches the target formation, and due to the high degree of karst fissure development in the target formation, resulting in complete fluid loss, the secondary casing can be run normally and the pipe securing operation can be successfully completed. This pipe securing operation meets design requirements and ensures the smooth progress of subsequent engineering projects.

[0004] A pipe fixing method under the condition of total loss of drilling fluid in the deflection section of a surface directional drilling technique, the pipe fixing method comprising the following steps:

[0005] 1) Directional drilling of a second opening in a surface water-damaged area, entering the target layer, and causing complete loss of drilling fluid;

[0006] Taking the positional relationship between the ground and the bottom of the second opening as the up-down relationship, lower the second opening casing with the slurry discharge hole opened near the lower pipe opening to the bottom of the second opening with the lower pipe end facing downwards;

[0007] 2) lowering the drill pipe until the lower end of the drill pipe near the bottom of the second opening is above the slurry discharge hole on the second opening casing;

[0008] 3) After calculating the volume V1 of the injected solid pipe slurry, inject the solid pipe slurry with a volume of V1 and the clean water with a volume of V2 through the slurry discharge holes on the double-opening casing in sequence;

[0009] 4) Drilling and setting;

[0010] 5) Drill down to explore the plug surface and obtain the hole depth L at the plug surface position 探 ;

[0011] L is the actual hole depth of the deflection section, H1=LL 探 Calculate H1;

[0012] H 计算 Calculate the contact length between the cement and casing for the design requirements of the pipe, and compare H1 with H 计算 ;

[0013] When H1≥H 计算 When the tube is fixed successfully, continue to wait for solidification;

[0014] When H1<H 计算 When the test is completed, the hole sweeping and pressure resistance tests are carried out in sequence;

[0015] When the pressure P' measured by the pressure test is greater than 1.2P and is stable for more than 30 minutes, the pressure test is qualified and the pipe is fixed successfully;

[0016] When the pressure P' measured by the pressure test is ≤1.2P or is stable for less than 30min, repeat steps 3) to 5) until the pressure test is qualified, and the pipe is successfully fixed;

[0017] Wherein, P is the calculated maximum pressure at the orifice of the slurry discharge hole when the pipe-fixing slurry is injected;

[0018] P' is the orifice pressure of the slurry discharge hole measured by the pressure test.

[0019] As another embodiment of the present application, in step 3), the volume of the pipe-fixing slurry injected is

[0020] wherein, is the diameter of the two open holes; the two open holes are used for running the two open sleeves.

[0021] As another embodiment of the present application, in step 3), the specific gravity of the pipe-cementing slurry is 1.65g / cm 3 .

[0022] As another embodiment of the present application, in step 3), the volume of the injected clean water is 0.5-1.0m

[0023] wherein, is the diameter of the drill pipe.

[0024] As another embodiment of the present application, the distance between the slurry leakage hole and the lower pipe mouth on the two open sleeves is 5-8m.

[0025] As another embodiment of the present application, at least one slurry leakage hole is arranged in parallel with the lower pipe mouth end on the two open sleeves.

[0026] As another embodiment of the present application, the diameter of the slurry leakage hole is 20-25mm.

[0027] As another embodiment of the present application, the distance between the lower end of the drill pipe and the end face of the lower pipe mouth of the two open sleeves is 9-12m.

[0028] As another embodiment of the present application, in step 3), before the injection of the pipe-cementing slurry, a certain amount of volume of plugging slurry is injected through the slurry leakage hole on the two open sleeves.

[0029] After the injection of the plugging slurry and before the injection of the pipe-cementing slurry, 4-6h of static state is required;

[0030] In step 4), the length of the standing time is 22-26h.

[0031] The pipe-cementing method under the full loss condition of the directional drilling fluid of the ground orientation technology provided by the present application has the beneficial effects that, compared with the prior art,

[0032] The method of the present application successfully solves the problems of high difficulty of pipe-cementing operation under the full loss condition, and high return of the sealing cement not reaching the ideal position; at the same time, if the conventional method of first plugging and then pipe-cementing is adopted, not only the safety of the open hole section cannot be ensured, but also the threat of the emergence of the swept hole and the new hole leading to the abandonment of the drilling hole; the method of the present application has strong reliability and high success rate, and can well solve the problem of rapid pipe-cementing under the full loss condition of the drilling fluid.

[0033] The present application directly avoids the hole bottom full leakage hole section by setting a slurry leakage hole on the modified two-opening sleeve, and performing sleeve fixing through repeatedly using the slurry leakage hole until the sleeve fixing requirement is reached, thereby ensuring the safety of the hole wall, improving the sleeve fixing quality, and saving cost and shortening construction period. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0035] Figure 1 Working schematic of the sleeve fixing method under the full leakage condition of the drilling fluid of the build-up section of the ground directional technology provided by the embodiments of the present application Figure 1 ;

[0036] Figure 2 Working schematic of the sleeve fixing method under the full leakage condition of the drilling fluid of the build-up section of the ground directional technology provided by the embodiments of the present application Figure 2 ;

[0037] Figure 3 Working schematic of the sleeve fixing method under the full leakage condition of the drilling fluid of the build-up section of the ground directional technology provided by the embodiments of the present application Figure 3 ;

[0038] Figure 4 Working schematic of the sleeve fixing method under the full leakage condition of the drilling fluid of the build-up section of the ground directional technology provided by the embodiments of the present application Figure 4 ;

[0039] H 计算 is the length of the sleeve fixing cement contacting with the sleeve calculated in the design;

[0040] L is the actual hole depth of the build-up section;

[0041] L 探 is the actual detection length between the slurry surface and the hole when the plug surface is detected, i.e. the hole depth of the plug surface position;

[0042] H1(H2) is the length of the sleeve fixing cement contacting with the sleeve actually obtained through the plug surface, i.e. H1(H2) = L-L 探 ;

[0043] is the hole diameter of the two-opening hole, is the inner diameter of the two-opening sleeve, is the diameter of the drill rod. DETAILED DESCRIPTION

[0044] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0045] Example 1 A pipe fixing method under full loss of drilling fluid in a build-up section of ground directional technology

[0046] The present example provides a pipe fixing method under full loss of drilling fluid in a build-up section of ground directional technology, as shown below Figures 1 to 4 The target layer of a ground area treatment project is a thick limestone layer with developed karst fissures, according to the design requirements, the diameter of the second opening hole in the build-up section is After drilling to a vertical depth of not less than 5m in the target layer, a second opening casing (i.e. a through-the-earth pipe) with a diameter of is lowered, and cement is used to permanently fix the pipe to a height of 计算 , and ensure that the pressure it can withstand is 1.2 times greater than the maximum pressure of the hole mouth of the slurry leakage hole, i.e. P' is greater than 1.2P (P is the maximum pressure of the slurry leakage hole when the pipe fixing slurry is injected), and stable for more than 30 minutes, which is considered to be qualified.

[0047] The specific implementation method is as follows:

[0048] 1) In a ground area treatment site, in the case of full loss of drilling fluid during drilling (the premise of simultaneous construction is that the construction section does not have hole collapse, block falling, etc., and the designed length of the second opening casing can be quickly lowered into the bottom of the second opening hole, which is also the bottom of the build-up section), the position relationship between the ground and the bottom of the second opening hole is the upper and lower relationship, and the second opening hole with a diameter of is opened (at this time, the second opening hole is the actual hole depth L of the build-up section drilling hole, i.e. the second opening build-up section has been drilled to the target layer (the second opening hole has been constructed to the target layer, at this time, the lowering of the casing does not affect the later engineering construction), which meets the hole depth for casing lowering, but the loss phenomenon increases the difficulty of the next pipe fixing operation, and there is a possibility that the cement return height of the hole sealing cannot reach the ideal position, which cannot meet the technical requirements of pipe fixing;

[0049] According to the design requirements for pipe fixing, the length H 计算 of the pipe fixing cement in contact with the casing (i.e. the expected pipe fixing length) is calculated;

[0050] First, at least one slurry leakage hole is provided on the second opening casing and parallel to the lower pipe port end, which is 5-8m away from the lower pipe port, and in the present implementation, the diameter of the slurry leakage hole is Two open casing is cut at 6m below the lower end with two slurry holes with a diameter of 20mm (the diameter of a general slurry hole is 20-25mm), and the open casing is lowered to the bottom of the open hole in a way that the lower end of the open casing is directed downward from the lower end of the open hole with the slurry hole near the lower end of the open casing, wherein

[0051] 2) After the open casing is lowered, a drill pipe with a diameter of 20mm is lowered to 10m from the lower end of the open casing (at this time, the lower end of the drill pipe near the bottom of the open hole is above the slurry hole of the open casing);

[0052] 3) A certain amount of lost circulation mud is first injected into the bottom of the open hole through the slurry hole of the open casing, and is left for 4-6h (5h in this embodiment), the volume of the injected lost circulation mud V1 is calculated, then lost circulation mud with a volume of V1 and a specific gravity of 1.65g / cm 3 is injected through the slurry hole of the open casing, and then clear water with a volume of V2 is injected through the slurry hole of the open casing;

[0053] wherein

[0054] 4) Then the drill pipe is pulled out and left to solidify for 24h;

[0055] 5) The drill pipe is lowered to the plug surface, and the depth L 探 of the plug surface is obtained (i.e. the actual detection length between the slurry surface and the hole during the detection of the plug surface);

[0056] The actual solidification length H1 (i.e. the depth of the actual plug surface and the bottom of the deviated hole) is calculated according to H1=L-L 探 ;

[0057] The actual plug surface is compared with the expected plug surface, i.e. H1 is compared with H 计算 ;

[0058] When H1≥H 计算 , it is proved that the actual solidification length reaches the expected solidification length, i.e. the actual plug surface reaches the expected plug surface, and the solidification is successful, and the left to solidify is continued;

[0059] When H1<H 计算 , such as Figure 2 , it is proved that the solidification length does not reach the expected position, and the hole is swept (the sweeping position should be 1.0-2.0m from the slurry hole, but cannot reach the bottom of the open casing, and generally the hole is swept to 4m from the bottom of the open casing), and a pressure test is performed, and the hole pressure P' of the slurry hole is measured if Figure 3 ;

[0060] ​When the pressure P' measured in the pressure test is greater than 1.2P and is stable for more than 30 minutes, the pipe is successfully cemented, and the pressure test is qualified;

[0061] When the pressure P' measured in the pressure test is less than or equal to 1.2P or is stable for less than 30 minutes, the pressure test is unqualified, and the steps 3) to 5) are performed again, for example, Figure 4 (Wherein, Figure 4 H2 in the formula corresponds to H1), until the pressure test is qualified, the pipe is successfully cemented.

[0062] The steps 3) to 5) performed again must be completed before the final setting of the cement.

[0063] Wherein, P is the maximum pressure of the hole orifice of the slurry hole when the cementing slurry is injected.

[0064] The present application injects the slurry through the slurry hole, and after the cementing is completed (i.e. after the cement setting is completed when the drilling is started), the cementing height is determined by the probe plug surface, the secondary cementing slurry is ensured to enter the cementing space only through the slurry hole by controlling the sweep hole position, the cementing effect is ensured, and the cementing quality is tested by the pressure test.

[0065] Example 2: A pipe cementing method under the full loss condition of a drilling fluid in a build-up section of a surface directional technology

[0066] The method in the present embodiment is basically the same as that in the example 1, and the difference is only that:

[0067] In the step 1), the diameter of the drill pipe in the present embodiment is Three slurry holes with a diameter of 25 mm are cut at a distance of 5 m from the lower end of the second casing;

[0068] In the step 2), the drill pipe with a diameter of is lowered to a distance of 9 m from the lower end of the second casing;

[0069] In the step 3), after the plugging slurry is injected and before the cementing slurry is injected, it is necessary to be still for 4 hours.

[0070] In the step 4), the time for the setting is 26 hours.

[0071] Example 3: A pipe cementing method under the full loss condition of a drilling fluid in a build-up section of a surface directional technology

[0072] The method in the present embodiment is basically the same as that in the example 1, and the difference is only that:

[0073] In the step 1), the diameter of the drill pipe in the present embodiment is Two slurry holes with a diameter of 21 mm are cut at a distance of 8 m from the lower end of the second casing;

[0074] In the step 2), the drill pipe with a diameter of drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing

[0075] In step 3), after injecting the lost circulation mud and before injecting the pipe stabilizing mud, 6h is needed for static state;

[0076] In step 4), the time for waiting for solidification is 22h.

[0077] In step 1), the drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing

[0078] In step 1), the drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing Two slurry holes with a diameter of 23mm are cut at a distance of 6m from the lower end of the second casing;

[0079] In step 2), the drill pipe with a diameter of 114.3mm is run to a distance of 11m from the lower end of the second casing In step 1), the drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing

[0080] In step 3), after injecting the lost circulation mud and before injecting the pipe stabilizing mud, 5h is needed for static state;

[0081] In step 4), the time for waiting for solidification is 23h.

[0082] A pipe stabilizing method under the condition of full loss of drilling fluid in a build-up section of a surface directional drilling technology

[0083] The method in this embodiment is basically the same as that in Embodiment 1, and the only difference is that:

[0084] In step 1), the drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing Two slurry holes with a diameter of 23mm are cut at a distance of 6m from the lower end of the second casing;

[0085] In step 2), the drill pipe with a diameter of 114.3mm is run to a distance of 11m from the lower end of the second casing In step 1), the drill pipe with a diameter of 114.3mm is run to a distance of 12m from the lower end of the second casing

[0086] In step 3), after injecting the lost circulation mud and before injecting the pipe stabilizing mud, 5h is needed for static state;

[0087] In step 4), the time for waiting for solidification is 23h.

[0088] The above is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of a surface directional drilling technique, characterized in that: The pipe fixing method comprises the following steps: 1) With the ground and the bottom of the second opening as the upper and lower relationship, the second opening is opened. A second opening casing with a slurry discharge hole near the lower pipe opening is lowered to the bottom of the second opening with the lower pipe end facing downwards. 2) Lowering the drill rod until the lower end of the drill rod near the bottom of the second opening is above the slurry drainage hole; 3) After calculating the volume V1 of the injected solid pipe slurry, inject the solid pipe slurry with a volume of V1 and the clean water with a volume of V2 through the slurry discharge holes on the secondary casing in sequence; 4) Drilling and consolidation; 5) Drill down to the plug surface and obtain the hole depth L at the plug surface position 探 ; L is the actual hole depth of the deflection section, H1=LL 探 Calculate the actual solid pipe length H1; H 计算 Calculate the contact length between the cement and casing for the design requirements of the pipe, and compare H1 with H 计算 ; When H1≥H 计算 When the tube is fixed successfully, continue to wait for solidification; When H1<H 计算 When the hole is swept, the pressure test is carried out in sequence; the hole sweeping position should be swept 1.0~2.0m beyond the slurry discharge hole, but not to the bottom of the secondary casing; When the pressure P' measured by the pressure test is greater than 1.2P and is stable for more than 30 minutes, the pressure test is qualified and the pipe is fixed successfully; When the pressure P' measured by the pressure test is ≤1.2P or is stable for less than 30min, repeat steps 3) to 5) until the pressure test is qualified, and the pipe is fixed successfully; Wherein, P is the calculated maximum pressure at the orifice of the slurry discharge hole when the pipe-fixing slurry is injected; P' is the orifice pressure of the slurry discharge hole measured by the pressure test; In step 3), the volume of the pipe-fixing slurry injected is V1=1.2 (H 计算 π (φ1 / 2) 2 ); Wherein, φ1 is the aperture of the second opening; the second opening is used to insert the second opening casing; In step 3), the volume of the clean water injected is V2 = (L-10)·π·(φ3 / 2) 2 ; Among them, φ3 is the diameter of the drill pipe.

2. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: In step 3), the specific gravity of the pipe-fixing slurry is 1.65 g / cm 3 .

3. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: The distance between the slurry discharge hole on the double-opening casing and the lower pipe opening is 5 to 8 meters.

4. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: At least one slurry discharge hole is provided on the double-open casing in parallel with the lower pipe end.

5. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: The diameter of the slurry discharge hole is 20-25 mm.

6. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: The distance between the lower end of the drill pipe and the end face of the lower pipe opening of the double-opening casing is 9 to 12 meters.

7. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 1, characterized in that: In step 3), before injecting the pipe-fixing slurry, a certain volume of plugging slurry needs to be injected through the slurry discharge hole on the double-opening casing.

8. The method for fixing pipes under the condition of total loss of drilling fluid in the deflection section of the surface directional drilling technology according to claim 7, characterized in that: In step 3); After injecting the plugging slurry and before injecting the pipe fixing slurry, it is necessary to wait for 4 to 6 hours; In step 4), the waiting time is 22 to 26 hours.

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