Active prevention and control method for deepwater shallow flow drilling

Abstract

The invention discloses an active prevention and control method for deepwater shallow flow drilling, belongs to the technical field of oil exploitation, and aims to solve the problem that a well wall is easy to collapse after a shallow flow stratum is drilled, the active prevention and control method for deepwater shallow flow drilling comprises a first mode or a second mode, according to the active prevention and control method for deepwater shallow flow drilling, a drilling tool, a casing pipe, a well cementation cement slurry system and the like are used in cooperation, the casing pipe and a drill bit enter a shallow flow stratum at the same time, the safety and efficiency of drilling the shallow flow stratum can be effectively improved, a shallow flow section is effectively packed, the well wall stability is improved, and the drilling cost is reduced. And disasters caused by relatively high shallow flow pressure are actively prevented and controlled. Therefore, safe and efficient drilling of the shallow water flow stratum in the drilling process is achieved.

Description

Technical Field

[0001] This invention relates to the field of oil extraction technology, specifically to an active control method for deep-water shallow flow drilling. Background Technology

[0002] Shallow flows tend to occur in geological environments where the sand body is loose and unconsolidated, has high porosity and permeability, is covered by low-permeability mud or shale, has a certain dip, and is of a certain volume, sufficient to generate a large amount of sand-water flow. They often occur during the initial drilling process.

[0003] When using seawater for open-path drilling, drilling through shallow flow formations can lead to complex disasters due to the high pressure of these shallow flows. Especially in deepwater drilling, where blowout preventer (BOP) assemblies are installed on the seabed, timely detection and handling of any overflow are crucial. Shallow flows can cause formation fracturing, damaging seabed equipment such as riser ruptures and BOPs falling to the seabed, resulting in significant economic losses and environmental pollution. Shallow flows can also interrupt drilling operations, requiring additional repair and control measures, increasing operation time and costs. The presence of high-pressure shallow gas can severely impact drilling safety; theoretically, gas ejection rates can reach hundreds of thousands of cubic meters per hour, potentially leading to serious blowout accidents. Summary of the Invention

[0004] To address the issue of wellbore collapse after drilling into shallow flow formations, this invention provides an active prevention and control method for deep-water shallow flow drilling. This method, through the coordinated use of drilling tools, casing, and cementing slurry systems, effectively improves the safety and efficiency of drilling into shallow flow formations, effectively isolates the shallow flow section, enhances wellbore stability, and actively prevents disasters caused by high shallow flow pressure. This achieves safe and efficient drilling into shallow flow formations.

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

[0006] An active control method for deep-water shallow flow drilling, including either the first method or the second method;

[0007] The first method includes the following steps in sequence:

[0008] Step 1a: Drill in the wellbore using the first drilling tool assembly;

[0009] Step 2a: When encountering shallow flow formations, clean the wellhead;

[0010] Step 3a: Assemble the second drill string assembly and run it into the wellbore. The second drill string assembly contains a casing, and the casing contains a drill bit, drill pipe, and drill collar connected in sequence; or, the second drill string assembly contains a casing, and the lower end of the casing is connected to the drill bit.

[0011] Step 4a: The second drill string assembly drills into the shallow flow formation;

[0012] Step 5a: After the second drill string assembly drills through the shallow flow formation, cementing operation is performed.

[0013] The second method includes the following steps in sequence:

[0014] Step 1b: Assemble a third drill bit assembly, which includes a casing containing a drill bit, drill pipe and drill collar connected in sequence. The casing is an expansion casing and the drill bit contains a hydraulic reamer.

[0015] Step 2b: The third drill string assembly is drilled into the wellbore;

[0016] Step 3b: After the second drill string assembly drills through the shallow flow formation, the drill bit, drill pipe, and drill collar are retrieved.

[0017] Step 4b: Increase the outer diameter of the casing and fit it against the well wall;

[0018] Step 5b: Perform cementing operations.

[0019] The beneficial effects of this invention are:

[0020] 1. Utilizing a conventional combination drill string, it can be flexibly applied in different formation sections. For example, the 16" PDC-BIT is used for efficient cutting, while the 8" DC is used for power transmission, improving drilling efficiency. Other auxiliary equipment is used for specific operations, such as vibration and shock. This increases the versatility of the drill string combination, adapting to different drilling needs. In addition, this drill string combination also has good wellbore control capabilities and adaptability.

[0021] 2. The cement slurry used has a lower system density due to the presence of foam, which helps alleviate wellbore pressure. By adjusting its rheological properties, it remains stable at different temperatures. After 24 hours, its compressive strength reaches over 4 MPa, ensuring cementing quality. This cement slurry system enables efficient cementing and plays an important role in the active control of shallow flow.

[0022] 3. By using conventional drill string combinations in conjunction with expansion casing and cementing slurry systems, the safety and efficiency of drilling into shallow flow formations can be effectively improved. This effectively isolates shallow flow sections, enhances wellbore stability, and proactively prevents disasters caused by high shallow flow pressure. Thus, safe and efficient drilling into shallow flow formations is achieved. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a schematic diagram of drilling in normal formations.

[0025] Figure 2 This is a schematic diagram of drilling in a shallow flow formation.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Wellbore; 2. Normal formation; 3. Drill collar; 4. Wellbore annulus; 5. Drill pipe; 6. Drill bit; 7. Hydraulic reamer; 8. Bypass valve; 9. Shallow flow formation; 10. Casing. Detailed Implementation

[0028] 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.

[0029] 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 based on actual needs or a limited number of experiments.

[0030] like Figures 1 to 2 As shown in the embodiment of the present invention, an active control method for deep-water shallow-flow drilling is provided. The active control method for deep-water shallow-flow drilling includes a first method or a second method, that is, the active control method for deep-water shallow-flow drilling can adopt the first method or the second method.

[0031] The first method includes the following steps in sequence:

[0032] Step 1a: Drill in wellbore 1 using the first drilling tool assembly;

[0033] Step 2a: When encountering shallow flow formation 9, clean the wellhead;

[0034] Step 3a: Assemble the second drill string assembly and run the second drill string assembly into the wellbore 1. The second drill string assembly contains a casing 10, and the casing 10 contains a drill bit 6, a drill pipe 5, and a drill collar 3 connected in sequence; or, the second drill string assembly contains a casing 10, and the lower end of the casing 10 is connected to the drill bit 6.

[0035] Step 4a: The second drill string assembly drills into the shallow flow formation 9;

[0036] Step 5a: After the second drilling tool assembly drills through the shallow flow formation 9, cementing operation is performed.

[0037] The second method includes the following steps in sequence:

[0038] Step 1b: Assemble the third drill bit assembly, which includes a casing 10, and the casing 10 contains a drill bit 6, a drill rod 5 and a drill collar 3 connected in sequence. The casing 10 is an expansion casing, and the drill bit 6 contains a hydraulic reamer 7.

[0039] Step 2b: The third drill string assembly is drilled in wellbore 1;

[0040] Step 3b: After the second drill bit assembly drills through the shallow flow formation 9, the drill bit 6, drill pipe 5 and drill collar 3 are pulled out.

[0041] Step 4b: Increase the outer diameter of casing 10 and fit it against the well wall;

[0042] Step 5b: Perform cementing operations.

[0043] The inventive point of this invention is that the casing 10 and the drill bit 6 enter the shallow flow formation 9 simultaneously. Compared with the prior art, where the drill bit 6 enters first and then the casing 10 enters, the casing 10 can always provide additional support to prevent wellbore collapse and also prepare for subsequent cementing operations.

[0044] The first method will be described in detail below:

[0045] In step 1a, to ensure smooth drilling while minimizing damage to drilling equipment, before commencing drilling operations, engineers select a suitable conventional drill string assembly based on geological conditions. This first assembly is an existing conventional drill string assembly. It typically includes drill bits and drill collars suitable for the hardness and temperature of the normal formation 2 (and non-shallow flow formations), as well as drill pipes and other auxiliary equipment capable of withstanding underground pressure. Then, the wellbore 1 is drilled using the first drill string assembly, and drilling (progression) is carried out in the normal formation 2.

[0046] In step 1a, the first drill string assembly includes a drill bit 6, drill pipe 5, and drill collar 3 connected in sequence. The drill bit 6 is a 16" PDC-BIT, the drill pipe 5 is a 5" DC, the casing 10 is a 13-3 / 8" casing, and other auxiliary equipment. The 16" PDC-BIT is used for efficient cutting, and the 8" DC is used for power transmission to improve drilling efficiency. Other auxiliary equipment is used for specific operations, such as vibration and shock. This increases the versatility of the drill string assembly, adapting to different drilling needs. In addition, the drill string assembly also has good wellbore control and adaptability.

[0047] The 16" PDC-BIT drill bit 6 is used for efficient cutting, while the drill pipe 5 can be an 8" DC type for power transmission, improving drilling efficiency. Other auxiliary equipment is used for specific operations, such as vibration and shock. This increases the versatility of the drill string assembly, adapting to different drilling needs. In the first method, when running the 13-3 / 8" casing 10, after drilling through shallow flow formations, a smaller drill bit needs to be replaced for drilling a new wellbore.

[0048] In step 2a, upon encountering (or approaching) the upper surface of the shallow flow formation 9, the first drill string assembly is first pulled out, and then a twin screw-assisted device is used to clean the wellhead to ensure that no impurities obstruct the entry of the drill bit.

[0049] In step 3a, when the shallow flow stratum 9 is an abnormally high-pressure underground sand body, the abnormally high-pressure underground sand body usually occurs in the range of 450m to 2000m water depth and 1100m to 1500m below the seabed mudline. At this time, the permeability of the shallow flow stratum 9 is 10md to 1000md and the porosity is 20% to 40%. The second drilling tool assembly adopts a combination of casing 10 and drill bit 6. The second drilling tool assembly contains casing 10, and the lower end of casing 10 is connected to drill bit 6.

[0050] When the shallow flow formation 9 is very soft and stable, the casing 10 is directly connected to the drill bit 6, and drilling can be completed without the use of drill rod 5 and drill collar 3. Especially in the shallow flow section, the direct drilling of the casing can penetrate the formation more quickly, while reducing the disturbance of the formation and protecting the integrity of the oil and gas reservoir.

[0051] In step 4a, the second drill string assembly drills into the shallow flow formation 9, that is, the second drill string assembly drills downward into the shallow flow formation 9.

[0052] In step 5a, after the second drill string assembly drills to the lower surface of the shallow flow formation 9, cementing operations are performed, namely cementing, waiting for the cement to harden, and ensuring the stability of the wellbore. Before cementing, the bypass valve 8 at the lower end of the casing 10 is opened by dropping a ball. During cementing, cement slurry is filled into the annular space (i.e., the wellbore annulus 4) between the casing 10 and the wellbore to ensure the stability of the wellbore and prevent possible future wellbore collapse.

[0053] The fluid loss of the cementing slurry is less than 100 cm³. 3 The cement slurry contains no free water and has a critical gel time of less than 30 minutes. Alternatively, the cement slurry can be a lightweight foamed cement slurry system, in which foaming agents and other liquid additives are added to silicate cement. The thickening time of the cement slurry at 18°C ​​is 3-5 hours, and the compressive strength of the cement slurry after 24 hours at 7-13°C reaches above 4 MPa.

[0054] The fluid loss of the cementing slurry is less than 100 cm³. 3 The high density of cement slurry, including a minimum temperature and humidity of 100°C, free water, and a critical gel time of less than 30 minutes, helps ensure the stability and reliability of the cement slurry, thereby reducing the risk of wellbore structure failure. Its novel lightweight foamed cement slurry system can rapidly achieve high compressive strength at low temperatures (thickening time of 3-5 hours at 18°C, and compressive strength exceeding 4 MPa after 24 hours at 7°C-13°C), ensuring the quality and efficiency of cementing operations even in harsh deep-water environments. The addition of foaming agents and other liquid additives to silicate cement makes the cement slurry more adaptable to the high-pressure and low-temperature environments of deep-water drilling, improving its performance under complex geological conditions.

[0055] When the second drill string assembly includes a casing 10, and the casing 10 contains a drill bit 6, a drill pipe 5, and a drill collar 3 connected in sequence, the first method further includes the following steps:

[0056] Step 6a: Release the drill pipe from the upper casing 10. This step requires taking precautions to avoid damaging the hardened wellbore. After release, the drilling rig can be used for other operations or to proceed with the next drilling segment.

[0057] Specifically, step 6a includes the following steps:

[0058] Step 6.1a: Clean the inside of the sleeve:

[0059] Before releasing the drill pipe, it is usually necessary to clean the inside of the casing to remove drill cuttings, cement slurry or other debris remaining in the casing.

[0060] Step 6.2a, Remove the blowout preventer:

[0061] If a blowout preventer (BOP) system is used, the BOP must be removed first.

[0062] Step 6.3a: Retrieve the drill pipe:

[0063] Operate the hoisting equipment of the drilling rig to gradually pull out the drill rod from inside the casing.

[0064] Step 6.4a, Inspect the drill pipe:

[0065] After the drill pipe has been completely pulled out, inspect it for damage, wear, or corrosion.

[0066] Step 6.5a, Cleaning and maintaining the drill pipe:

[0067] Clean and perform necessary maintenance on the drill pipe in preparation for future use.

[0068] Step 6.6a, Store or prepare for next use:

[0069] After cleaning and inspection, store the drill pipe or prepare it for the next drilling operation.

[0070] Step 6.7a, Prepare the wellhead:

[0071] After cementing and drill pipe release are completed, wellhead equipment may need to be installed to prepare for subsequent operations such as logging, completion, or production.

[0072] In the second method, an expansion casing is run in, and only the shallow flow section is isolated. Simultaneously, a hydraulic reamer is installed in the drill string to enlarge the diameter of the shallow flow section. The second method is described in detail below:

[0073] Step 1b: First, upgrade the conventional drilling tool assembly to a drill bit, drill collar, expansion casing, and drill pipe suitable for the hardness and temperature of shallow flow formations, thus creating a third drilling tool assembly. The third drilling tool assembly contains a casing 10, which contains a drill bit 6, a drill pipe 5, and a drill collar 3 connected in sequence. The casing 10 is an expansion casing, and the drill bit 6 contains a hydraulic reamer 7.

[0074] Step 2b: Slowly lower the third drill string assembly into the wellbore 1, and drill downwards in the wellbore 1; In the second method, after drilling through the shallow flow formation 9, there is no need to change the drill bit. The depth of the first well opening is greater than the depth of the shallow flow, which can reduce the length of the second well opening and the complex formation conditions in the second well opening, and greatly improve the safety of drilling through shallow flow.

[0075] Step 3b: After the second drill bit assembly drills through the shallow flow formation 9, the drill bit 6, drill pipe 5 and drill collar 3 are pulled out.

[0076] Step 4b: Insert the cementing ball into the well to prepare for cementing operations. By controlling the wellhead pressure, prevent the well wall from collapsing and increase the outer diameter of the casing 10 to fit the well wall.

[0077] Step 5b: Perform cementing operations, i.e., cementing, waiting for setting, and cement strength building: Waiting for the cement to harden achieves the isolation of the shallow water flow high-pressure layer, ensuring wellbore stability. Before cementing, the bypass valve 8 at the lower end of casing 10 is opened by dropping a ball. During cementing, cement slurry is filled into the annular space (i.e., wellbore annulus 4) between casing 10 and the wellbore to ensure wellbore stability and prevent potential future wellbore collapse.

[0078] The fluid loss of the cementing slurry is less than 100 cm³. 3 The cement slurry contains no free water and has a critical gel time of less than 30 minutes. Alternatively, the cement slurry can be a lightweight foamed cement slurry system, in which foaming agents and other liquid additives are added to silicate cement. The thickening time of the cement slurry at 18°C ​​is 3-5 hours, and the compressive strength of the cement slurry after 24 hours at 7-13°C reaches above 4 MPa.

[0079] The second method also includes the following steps:

[0080] Step 6b: Re-run the first drill string assembly and continue drilling. After drilling to the designed well depth, run the casing 10 and seal the entire well section to ensure the stability of the entire well section.

[0081] 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 method for active control of shallow flow in deep-water drilling, characterized in that, The active control method for deep-water shallow flow drilling includes either the first method or the second method; The first method includes the following steps in sequence: Step 1a: Drill in the wellbore (1) using the first drilling tool assembly; Step 2a: When encountering a shallow flow formation (9), clean the wellhead; Step 3a: Assemble the second drill string assembly and run the second drill string assembly into the wellbore (1). The second drill string assembly contains a casing (10), and the casing (10) contains a drill bit (6), a drill pipe (5), and a drill collar (3) connected in sequence; or, the second drill string assembly contains a casing (10), and the lower end of the casing (10) is connected to the drill bit (6). Step 4a: The second drill string assembly drills into the shallow flow formation (9); Step 5a: After the second drilling tool assembly drills through the shallow flow formation (9), cementing operation is carried out; The second method includes the following steps in sequence: Step 1b: Assemble the third drill bit assembly, which includes a casing (10), and the casing (10) contains a drill bit (6), a drill rod (5) and a drill collar (3) connected in sequence. The casing (10) is an expansion casing, and the drill bit (6) contains a hydraulic reamer (7). Step 2b: The third drill string assembly is drilled in the wellbore (1); Step 3b: After the second drill bit assembly drills through the shallow flow formation (9), the drill bit (6), drill rod (5) and drill collar (3) are pulled out. Step 4b: Increase the outer diameter of the casing (10) and fit it against the well wall; Step 5b: Perform cementing operations.

2. The active control method for deep-water shallow-flow drilling according to claim 1, characterized in that, In step 1a, the first drill assembly includes a drill bit (6), a drill pipe (5) and a drill collar (3) connected in sequence. The drill bit (6) is a 16"PDC-BIT and the drill pipe (5) is a 5"DC.

3. The active control method for deep-water shallow-flow drilling according to claim 1, characterized in that, In step 2a, a twin-screw auger is used to clean the wellhead.

4. The active control method for deep-water shallow flow drilling according to claim 1, characterized in that, In step 3a, when the permeability of the shallow flow formation (9) is 10 md to 1000 md and the porosity is 20% to 40%, the second drill assembly contains a casing (10) with a drill bit (6) connected to the lower end of the casing (10).

5. The active control method for deep-water shallow flow drilling according to claim 1, characterized in that, In steps 5a and 5b, before cementing operations are performed, the bypass valve (8) at the lower end of the casing (10) is opened by dropping a ball.

6. The active control method for deep-water shallow-flow drilling according to claim 1, characterized in that, In steps 5a and 5b, during the cementing operation, cementing slurry is filled into the annular space between the casing (10) and the well wall.

7. The active control method for deep-water shallow flow drilling according to claim 6, characterized in that, The fluid loss of the cementing slurry is less than 100 cm³. 3 / h, the cement slurry contains no free water, and the critical gel time of the cement slurry is less than 30min.

8. The active control method for deep-water shallow flow drilling according to claim 6, characterized in that, The cementing slurry is a lightweight foamed cement slurry. The thickening time of the cementing slurry at 18℃ is 3-5 hours. The compressive strength of the cementing slurry after 24 hours at 7℃-13℃ reaches more than 4 MPa.

9. The active control method for deep-water shallow flow drilling according to claim 1, characterized in that, When the second drill string assembly includes a casing (10), and the casing (10) contains a drill bit (6), a drill pipe (5), and a drill collar (3) connected in sequence, the first method further includes the following steps: Step 6a: Release the drill rod at the top of the upper casing (10).

10. The active control method for deep-water shallow flow drilling according to claim 9, characterized in that, Step 6a includes the following steps: Step 6.1a: Clean the inside of the sleeve; Step 6.2a: Remove the blowout preventer; Step 6.3a: Remove the drill pipe; Step 6.4a: Inspect the drill pipe; Step 6.5a: Clean and maintain the drill pipe; Step 6.6a: Store or prepare for next use; Step 6.7a: Prepare the wellhead.

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