Anti-friction well drilling casing pipe

Abstract

The invention discloses an antifriction well drilling casing pipe, relates to the technical field of oil and gas well drilling, and further relates to the antifriction well drilling casing pipe. Comprising a plurality of casing pipe sections which are spliced end to end, a plurality of concave groove grooves are formed in the outer surfaces of at least one part of the casing pipe sections, the outer surfaces of the casing pipe sections are coated with water-insoluble lubricating agents, the lubricating agents are distributed in the outer surfaces of the casing pipe sections and the groove grooves, and the water-insoluble lubricating agents are contained in the groove grooves; compared with the outer surface, the quantity of the lubricant in the groove grooves is more, the lubricant continuously seeps to the outer surface in the drilling process, lubrication can be formed on the contact face of the casing section and the stratum, and the effect of reducing friction is achieved; according to the anti-friction well drilling casing pipe, in the well drilling process, lubricating agents do not need to be continuously conveyed downwards, only the lubricating agents need to be coated at a time before well drilling, and the construction process is simpler and more convenient.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling technology, and more particularly to a friction-reducing drilling casing. Background Technology

[0002] Casing drilling technology, as a cutting-edge drilling innovation, breaks away from the traditional two-step drilling operation model, which involves drilling first and then running the casing. Using customized casing or liner as the core component of the drill string, instead of conventional drill pipe, it enables parallel processing of drilling and casing installation, with the casing remaining underground after drilling. This technology not only allows for casing placement during drilling but also simplifies the separate processes of casing placement and cementing, thereby significantly reducing the overall operation time and improving drilling speed and efficiency.

[0003] In oil and gas extraction, casing drilling technology plays a crucial role. Because the casing is tightly fitted to the wellbore, the frictional resistance between them can become extremely high during drilling, potentially damaging the threads at the casing connection and increasing energy consumption. Common friction-reduction methods in the machinery industry include the use of lubricating oils or greases, but these methods lack effective load-bearing and transmission capabilities and are not applied to reduce friction between the casing and the wellbore in casing drilling operations. A common practice is to directly mix lubricant into water-based drilling fluids to reduce friction. However, due to the dilution effect of drilling fluids, the effectiveness of this lubrication method is often limited, requiring large amounts to achieve a noticeable friction-reduction effect.

[0004] For those skilled in the art, how to reduce friction during casing drilling is a technical problem that needs to be solved. Summary of the Invention

[0005] This invention provides a friction-reducing drilling casing, which has several grooves on the outer surface of the casing sections to gradually release lubricant during drilling, thereby reducing friction during the drilling process. The specific solution is as follows:

[0006] A friction-reducing drilling casing includes several casing segments spliced ​​end to end. At least a portion of the casing segments have several recessed grooves on their outer surfaces. The outer surfaces of the casing segments are coated with a water-insoluble lubricant, and the grooves are used to contain the water-insoluble lubricant. The casing segments are used to contact the formation during drilling and reduce friction through the lubricant.

[0007] Optionally, the depth of the groove does not exceed one-half of the thickness of the sleeve segment.

[0008] Optionally, the opening angle of the groove is opposite to the rotation direction of the sleeve segment.

[0009] Optionally, an oil-absorbing resin layer is embedded at the bottom of the groove.

[0010] Optionally, the oil-absorbing resin layer is adhered to the sidewall of the sleeve segment using an adhesive.

[0011] Optionally, the oil-absorbing resin layer is an oil-absorbing resin carried on a fabric, or a granular solid resin coated on a non-woven fabric.

[0012] Optionally, the grooves are spirals, wavy lines, or straight lines.

[0013] Optionally, the two ends of the groove extend to the two ends of the sleeve segment; or the groove is distributed at intervals along the axial and circumferential directions.

[0014] Optionally, the lubricant is one or more of the following: oleophilic surfactant, crude oil, mineral oil, engine oil, and grease.

[0015] Optionally, the groove is a wedge-shaped cross-section with a small opening and a large bottom or a large opening and a small bottom, or a slot with a uniform width.

[0016] This invention provides a friction-reducing drilling casing, comprising several casing segments joined end-to-end. At least a portion of the casing segments have several recessed grooves on their outer surfaces. The outer surfaces of the casing segments are coated with a water-insoluble lubricant, which is distributed on both the outer surfaces and within the grooves. The grooves contain the water-insoluble lubricant. Compared to the outer surface, the grooves contain a larger amount of lubricant, which continuously seeps out to the outer surface during drilling, forming lubrication at the contact surface between the casing segment and the formation, thereby reducing friction. The friction-reducing drilling casing provided by this invention does not require continuous downward delivery of lubricant during drilling; lubricant only needs to be applied once before drilling, simplifying the construction process. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is an isometric schematic diagram of the first embodiment of the sleeve segmentation of the present invention;

[0019] Figure 2 This is an isometric schematic diagram of the second embodiment of the sleeve segmentation of the present invention;

[0020] Figure 3This is an isometric schematic diagram of the third embodiment of the sleeve segmentation of the present invention;

[0021] Figure 4 This is an isometric schematic diagram of the fourth embodiment of the sleeve segmentation of the present invention;

[0022] Figure 5 A schematic diagram showing the installation of an oil-absorbing resin layer inside the groove;

[0023] Figure 6 Another schematic diagram showing the installation of an oil-absorbing resin layer inside the groove.

[0024] The image includes:

[0025] The casing is divided into sections 1, grooves 2, and oil-absorbing resin layer 3. Detailed Implementation

[0026] The core of this invention is to provide a friction-reducing drilling casing, which has several grooves on the outer surface of the casing sections to gradually release lubricant during the drilling process, thereby reducing friction during the casing drilling process.

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the friction-reducing drilling casing of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] This invention provides a friction-reducing drilling casing, comprising several casing segments 1 spliced ​​end-to-end, with each casing segment 1 fixed relative to the others, spliced ​​together to form a friction-reducing drilling casing. The lengths of the casing segments 1 may be equal or unequal. When the casing segments 1 are spliced ​​together to form a friction-reducing drilling casing, its upper end is connected to a rotary power mechanism, and its lower end extends below the ground surface, drilling into the ground surface during continuous rotation.

[0029] In the several casing segments 1 constituting the friction-reducing drilling casing, at least a portion of the casing segments 1 have several recessed grooves 2 on their outer surfaces. The casing segments 1 with the grooves 2 are located at the front of the entire friction-reducing drilling casing, that is, the outer surfaces of the first one or several casing segments 1 have the grooves 2. It should be noted that the dimensions and shapes of the various grooves 2 can be the same or different, and the depth can be large or small. It is not required that all the grooves 2 adopt the same size design.

[0030] The casing section 1 is a cylindrical pipe structure. The groove 2 is a recessed groove on the outer surface of the casing section 1, which forms a receiving space. The outer surface of the casing section 1 is coated with a water-insoluble lubricant, such as high-efficiency lubricating oil or grease. Because the groove 2 has a larger receiving space, it can hold more water-insoluble lubricant. During drilling, the lubricant in the groove 2 does not directly contact the well wall, and is gradually and slowly released outward.

[0031] The outer surface of casing section 1 comes into contact with the formation during drilling, and friction is reduced by lubricant. During drilling, the lubricant in the grooves 2 is continuously released outward, achieving a continuous lubrication effect on the outer surface of casing section 1. A low-flow lubricant is used. During drilling, the friction temperature between casing section 1 and the well wall continuously rises. As the temperature rises, the flowability of the lubricant increases, and the lubricant continuously flows outward from the grooves 2 to reach the outer surface of casing section 1, maintaining the lubrication effect.

[0032] Therefore, it can be seen that the friction-reducing drilling casing provided by this invention does not require continuous downward delivery of lubricant from the surface during drilling. Lubricant only needs to be applied once to the outer surface of the casing section 1 before drilling. The grooves 2 contain a certain amount of lubricant, maintaining the lubrication effect during drilling, making the construction process simpler. After drilling to a suitable depth below the surface, the friction-reducing drilling casing of this invention remains underground, functioning as a pipeline.

[0033] Based on the above scheme, this invention limits the size of the groove 2. The depth of the groove 2 does not exceed half the thickness of the sleeve segment 1. Generally, the thickness of the entire sleeve segment 1 wall is uniformly distributed along the circular direction, but this does not exclude the possibility that the wall thickness of the sleeve segment 1 may change along the axial direction. The depth of the groove 2 does not exceed half of its location, thereby ensuring the structural strength of the sleeve segment 1. Combined with... Figure 5 As shown, T represents the thickness of casing segment 1, and L represents the depth of groove 2, where 2L ≤ T. Groove 2 should ideally avoid sharp angles, forming smooth rounded corners to reduce stress concentration. The depth, width, and spacing of the grooves can be designed in various ways, ensuring sufficient oil storage space while also considering the mechanical strength and wear resistance of the casing, ensuring that lubrication efficiency is improved without affecting the overall stability and service life of the casing.

[0034] In some embodiments, the opening angle of the groove 2 is opposite to the rotation direction of the sleeve segment 1. Combined with... Figure 6 As shown, the groove 2 is inclined. Figure 6When the sleeve segment 1 rotates clockwise, the opening angle of the groove 2 faces counterclockwise. When the sleeve segment 1 rotates, it can reduce the scraping of the surface of the groove 2, reduce friction, and slow down the speed at which the lubricant flows out, which helps to achieve a long-lasting lubrication effect.

[0035] The opening angle of the groove 2 is opposite to the rotation direction of the sleeve segment 1 as a specific embodiment, but other configurations are not excluded. Figure 5 As shown, the groove 2 is a straight groove, and the groove 2 is symmetrically arranged about a certain diameter of the sleeve segment 1.

[0036] An oil-absorbing resin layer 3 is embedded at the bottom of the groove 2. Each groove 2, or several grooves 2, has a layer of oil-absorbing resin embedded at its bottom. The oil-absorbing resin is a high-molecular-weight material synthesized through a special process, primarily used for adsorbing and recovering oil, and possesses excellent oil-water separation performance. In this invention, the high oil absorption and slow release characteristics of the oil-absorbing resin effectively absorb and store lubricating oil or grease, ensuring a stable supply of lubricant and preventing rapid loss.

[0037] The oil-absorbing resin layer 3 is bonded to the sidewall of the casing section 1 with an adhesive, reducing the probability of it falling off during drilling.

[0038] The oil-absorbing resin layer 3 consists of oil-absorbing resin loaded onto fabric or granular solid resin coated onto nonwoven fabric. The oil-absorbing resin can be designed with a highly developed pore structure, possessing a large specific surface area, effectively adsorbing and storing large amounts of oil. Oil-absorbing resin can be manufactured in various forms; for example, the fabric type involves loading the oil-absorbing resin onto fabric, and the loading amount can be adjusted as needed. The coated type involves coating granular solid resin onto nonwoven fabric. In some cases, an adhesive layer needs to be applied between the resin and the casing surface to ensure that the resin does not easily detach during long-term use. Lubricant is evenly applied or injected onto the grooves and oil-absorbing resin, utilizing the resin's oil-absorbing properties to ensure that the lubricating material is continuously and evenly distributed on the casing-wellbore contact surface during drilling, significantly reducing the coefficient of friction.

[0039] Based on any of the above technical solutions and their combinations, the groove 2 used in this invention is a spiral, wavy, or straight line, combined with... Figure 1 , Figure 2 , Figure 4 As shown, the grooves 2 used extend along the axial direction in their length direction, and all grooves 2 extend in a straight line. Combined with... Figure 3As shown, the groove 2 used has a spiral structure along its length, which can be either clockwise or counterclockwise. These specific configurations should all be included within the scope of protection of this invention. In addition, the groove 2 can also be designed with a combination of straight lines and spirals.

[0040] The grooves can also be specially designed with specific geometries, such as wavy shapes, to increase the contact area between the casing surface and the lubricating material, while promoting the dynamic distribution of the lubricating material during casing rotation. Compared to ordinary casing, these grooved casings can hold a larger amount of lubricant after being coated with lubricating oil or grease.

[0041] Specifically, the grooves 2 extend to the ends of the sleeve segment 1 at both ends; or the grooves 2 are spaced apart axially and circumferentially. (Combined) Figure 1 , Figure 2 , Figure 3 As shown, the groove 2 extends through the entire sleeve segment 1, with both ends of the groove 2 extending to both ends of the sleeve segment 1. The length of the groove 2 is greater than or equal to the axial length of the sleeve segment 1. (Combined with...) Figure 4 As shown, the grooves 2 are distributed at intervals along the axial and circumferential directions. The grooves 2 are arrayed on the outer surface of the sleeve segment 1, and the length of each groove 2 is shorter than the axial length of the sleeve segment 1. In addition, the grooves 2 can also be of varying lengths, with some being longer and others shorter, forming a staggered distribution of lengths. These specific implementations should all be included within the protection scope of this invention.

[0042] When the two ends of the groove 2 extend to the two ends of the casing section 1, since the groove 2 is completely through, the lubricant can flow downwards along the groove 2, and lubricant can be added from above during the downward drilling process. Figure 4 The grooves 2 shown are arranged in an array, and the lubricant in each groove 2 can be independent of each other, which can avoid the problem of all the lubricant flowing downward.

[0043] Specifically, the lubricant used in this invention is one or more of the following: lipophilic surfactants, crude oil, mineral oil, engine oil, and grease. A suitable lubricant or grease is selected based on the temperature, pressure, and required lubrication performance of the drilling environment. Due to high bottom-hole temperatures, high-viscosity lubricants are typically chosen, applied on the drilling platform during drilling using processes such as spraying or dipping. Crude oil can also be used directly as the lubricant. Both ordinary and heavy crude oil can be used. Heavy oil has a higher viscosity than ordinary crude oil. It is crucial to ensure that the grooves are fully filled with lubricating material to form a stable lubricating film and reduce frictional resistance. Waste engine oil can also be used as the lubricant.

[0044] Mineral oils and vegetable oils can also be used as lubricants, each with different properties, and the choice depends on the specific working conditions. Additionally, grease is another commonly used semi-solid lubricant, often referred to as "butter." Depending on the base oil, there are many types of greases available on the market, including calcium-based, sodium-based, lithium-based, lithium complex-based, and bentonite greases. These different types of greases each have unique performance characteristics and are suitable for different working conditions and requirements.

[0045] Groove 2 has a wedge-shaped cross-section with a small opening and a large bottom, or a large opening and a small bottom, or a groove with a uniform width. (Combined) Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the groove 2 depicted has a wedge-shaped cross-section with a large opening and a small base. Figure 2 The groove 2 shown is a wedge-shaped cross-section with a small opening and a large bottom; the groove 2 can also be a slotted structure with a uniform width at each position, and these specific structures should all be included within the protection scope of this invention.

[0046] This invention provides a specific operating procedure:

[0047] During the casing section 1 processing stage, a series of upper grooves 2 are first engraved on the casing section 1. The opening ends of these grooves 2 are designed to be counterclockwise, which is the opposite of the conventional clockwise rotation drilling operation. The purpose is to ensure that the lubricant can be effectively stored in the grooves during drilling operations.

[0048] During casing drilling operations, lubricant is applied to the surface of casing section 1 and the interior of grooves 2 on the drill platform. The lubricant application process can be performed simultaneously with drilling to maintain continuous and effective lubrication. While crude oil can be used as the lubricant, for improved environmental standards and operational efficiency, an automated application system is recommended for uniform and efficient application.

[0049] An adhesive is used to embed the oil-absorbing resin layer 3 into the grooves 2. The oil-absorbing resin layer 3 is a polymer material synthesized through a special process, mainly used for adsorbing and recovering oil, and has excellent oil-water separation performance. A porous oil-absorbing resin is used. This resin has a highly developed specific surface area through a special pore structure design, which can effectively adsorb and store a large amount of oil. The oil-absorbing resin adopts a coating type, in which granular solid resin is coated with non-woven fabric.

[0050] The adhesive used to bond the oil-absorbing resin layer 3 to the grooves in the steel casing is an epoxy resin adhesive. Epoxy resin is the preferred choice for bonding steel and oil-absorbing resin due to its excellent mechanical strength, chemical resistance, and oil resistance. They cure at room temperature, and once cured, the resulting adhesive layer is very tough.

[0051] In practice, surface treatment is performed before applying the adhesive, including thoroughly cleaning the steel surface of grease and oxide layers to ensure optimal bonding results.

[0052] Liquid adhesive is evenly applied to the bottom of groove 2 using a syringe, followed by filling with oil-absorbing resin, and allowed to cure. Afterwards, sleeve section 1 should be carefully inspected to ensure the resin layer is uniform and firmly bonded.

[0053] Using the above method, the oil-absorbing resin can be effectively embedded in the grooves of the casing. Then, during casing drilling, a lubricant that is insoluble in water is applied to the surface and grooves of the invented casing.

[0054] During casing drilling, a low friction value can be observed, indicating that this casing has a significant lubrication effect. During drilling operations, as the casing 1 rotates and drills, once it contacts the well wall, the crude oil located in the grooves 2 is squeezed out, forming a lubricating film on both the casing surface and the well wall, thereby effectively reducing the friction between the casing section 1 and the well wall.

[0055] As can be seen from the above description, the present invention achieves the lubrication effect using the following methods:

[0056] Self-lubricating casing design: The core innovation of this system lies in the specific groove structure designed on the outer surface of the casing. These grooves can not only store lubricant, but the structure itself is also specially optimized for water-based drilling fluid environment, aiming to solve the problems of high frictional resistance and severe wear of traditional casing during drilling.

[0057] Detailed design of the groove structure: As mentioned above, the groove depth does not exceed half the thickness of the casing and the opening angle is counterclockwise. These design details may be to optimize the lubricant retention capacity, reduce fluid resistance during drilling, and at the same time ensure the strength and stability of the casing structure.

[0058] Application of oil-absorbing resin layer: In some implementations, an oil-absorbing resin layer is embedded in the bottom of the groove and fixed with an adhesive. This design further enhances the lubricant storage and slow release mechanism, ensuring a continuous supply of lubricant during long-term operations, reducing maintenance needs and improving drilling efficiency.

[0059] Specifically designed casing outer surface groove structures and their application in water-based drilling fluid environments. A technology combining the selection of water-insoluble lubricants with effective storage and release mechanisms within the grooves. An innovative approach to oil-absorbing resin layers and their fixation methods, enhancing lubrication performance and extending lubrication cycles. A method for applying lubricant during drilling to maintain efficient lubrication.

[0060] The friction-reducing drilling casing of the present invention has the following beneficial effects:

[0061] Significant drag reduction: The combination of grooved structure and lubricating materials effectively reduces the frictional resistance of the casing during drilling, increasing drilling speed and reducing energy consumption. The application of oil-absorbing resin increases the lubricant's shelf life.

[0062] It reduces sleeve wear caused by friction, especially when excessive friction can damage the threads of the sleeve connection.

[0063] High environmental adaptability: The type of lubricating material and groove design can be flexibly selected and adjusted according to different drilling environments and conditions, thereby improving the universality and adaptability of the technology.

[0064] Simple construction: The groove processing and lubrication material coating process is simple and easy to implement, and can be easily integrated into the existing drilling operation process without major equipment modification.

[0065] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A reduced friction drilling casing, characterized by, The casing includes several casing segments (1) that are spliced ​​together end to end. At least a portion of the casing segments (1) have several recessed grooves (2) on their outer surfaces. The outer surfaces of the casing segments (1) are coated with a water-insoluble lubricant. The grooves (2) are used to contain the water-insoluble lubricant. The casing segments (1) are used to contact the formation during drilling and to reduce friction through the lubricant.

2. The reduced friction drilling casing of claim 1, wherein, The depth of the groove (2) does not exceed half the thickness of the sleeve segment (1).

3. The reduced friction drilling casing of claim 1, wherein, The opening angle of the groove (2) is opposite to the rotation direction of the sleeve segment (1).

4. The reduced friction drilling casing of any one of claims 1 to 3, wherein, The bottom of the groove (2) is embedded with an oil-absorbing resin layer (3).

5. The reduced friction drilling casing of claim 4, wherein, The oil-absorbing resin layer (3) is adhered to the side wall of the sleeve segment (1) by an adhesive.

6. The reduced friction drilling casing of claim 5, wherein, The oil-absorbing resin layer (3) is an oil-absorbing resin carried on a fabric, or a granular solid resin coated on a non-woven fabric.

7. The reduced friction drilling casing of any one of claims 1 to 3, wherein, The groove (2) is a spiral, a wavy line or a straight line.

8. The reduced friction drilling casing of claim 7, wherein, The two ends of the groove (2) extend to the two ends of the sleeve segment (1); or the groove (2) is distributed at intervals along the axial and circumferential directions.

9. The reduced friction drilling casing of claim 1, wherein, Lubricants are one or more of the following: lipophilic surfactants, crude oil, mineral oil, engine oil, and grease.

10. The reduced friction drilling casing of claim 1, wherein, The groove (2) is a wedge-shaped cross section with a small opening and a large bottom or a large opening and a small bottom, or a groove with a consistent width.

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