Anti-friction well drilling casing pipe

Abstract

The utility model 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, lubricating agents do not need to be continuously conveyed downwards in the well drilling process, 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] The utility model relates to the technical field of oil and gas drilling, and further relates to a friction-reducing drilling casing. Background Art

[0002] As a cutting-edge drilling innovation, casing drilling technology breaks the old mode that traditional drilling operations must be carried out in two steps, that is, first drilling a hole and then running the casing. By using a customized casing or liner as the core component of the drill string instead of a conventional drill pipe, the parallel processing of drilling and casing installation is achieved, and the casing remains underground after drilling down. This technology can not only place the casing while drilling, but also simplify the process of separately placing the casing and cementing, thus greatly reducing the overall duration of the operation and improving the drilling speed and efficiency.

[0003] In the process of oil and gas exploitation, casing drilling technology plays a crucial role. Since the casing is in close contact with the wellbore wall, the frictional resistance between the two may become very large during drilling, which may damage the threads at the casing connection part and also lead to an increase in energy consumption. Commonly used friction-reducing means in the machinery industry include using lubricating oil or grease, but these methods are not applied to reduce the friction between the casing and the wellbore wall in casing drilling operations due to the lack of effective load-bearing and transmission functions. Usually, the lubricant is directly mixed into the water-based drilling fluid to reduce the friction between the casing and the wellbore wall. However, due to the dilution effect of the drilling fluid, the effect of this lubrication method is often limited, so a large amount needs to be added to achieve a certain friction-reducing effect.

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

[0005] The utility model provides a friction-reducing drilling casing, and a number of groove patterns are arranged on the outer surface of the segmented casing to gradually release the lubricant during the drilling process, thereby reducing the friction during the casing drilling process. The specific solution is as follows:

[0006] A friction-reducing drilling casing includes a number of casing segments spliced end to end, and a number of recessed groove patterns are arranged on the outer surface of at least a part of the casing segments. The outer surface of the casing segments is coated with a water-insoluble lubricant, and the groove patterns are used to accommodate 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 pattern does not exceed one-half of the thickness of the casing segment.

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

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

[0010] Optionally, the oil-absorbing resin layer is adhered to the side wall of the casing segment by 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 grooved channel is a spiral line, a wavy line or a straight line.

[0013] Optionally, both ends of the grooved channel extend to both ends of the casing segment; or the grooved channels are distributed at intervals along the axial and circumferential directions.

[0014] Optionally, the lubricant is one or several of lipophilic surfactants, crude oil, mineral oil, machine oil, and grease.

[0015] Optionally, the grooved channel has a wedge-shaped cross-section with a small top and a large bottom or a large top and a small bottom, or a slotted opening with a uniform width.

[0016] The utility model provides a friction-reducing drilling casing, which comprises a plurality of casing segments spliced end to end. The outer surface of at least a part of the casing segments is provided with a plurality of sunken grooved channels. The outer surface of the casing segment is coated with a water-insoluble lubricant. The lubricant is distributed on the outer surface and in the grooved channels of the casing segment. The grooved channels accommodate the water-insoluble lubricant. Relative to the outer surface, the amount of the lubricant in the grooved channels is more. During the drilling process, the lubricant continuously seeps out to the outer surface, and lubrication can be formed on the contact surface between the casing segment and the formation, achieving the effect of reducing friction. The friction-reducing drilling casing provided by the utility model does not need to continuously convey the lubricant downward during the drilling process, and only needs to coat the lubricant once before drilling, and the construction process is more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is an axonometric schematic diagram of the first embodiment of the casing segment of the present utility model;

[0019] Figure 2 It is an axonometric schematic diagram of the second embodiment of the casing segment of the present utility model;

[0020] Figure 3Isometric schematic diagram of the third embodiment of the sleeve segmentation of the present utility model;

[0021] Figure 4 Isometric schematic diagram of the fourth embodiment of the sleeve segmentation of the present utility model;

[0022] Figure 5 Schematic diagram of an oil-absorbing resin layer provided in the grooved channel;

[0023] Figure 6 Another schematic diagram of an oil-absorbing resin layer provided in the grooved channel.

[0024] The figure includes:

[0025] Sleeve segmentation 1, grooved channel 2, oil-absorbing resin layer 3. Specific implementation manners

[0026] The core of the present utility model is to provide a friction-reducing drilling casing. A number of grooved channels are provided on the outer surface of the sleeve segmentation. During the drilling process, lubricant is gradually released, thereby reducing the friction during the casing drilling process.

[0027] In order to enable those skilled in the art to better understand the technical solution of the present utility model, the friction-reducing drilling casing of the present utility model will be introduced and described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0028] The present utility model provides a friction-reducing drilling casing, which includes a number of sleeve segmentations 1 spliced end to end. Each sleeve segmentation 1 is relatively fixed to each other, and is spliced and fixed to form a friction-reducing drilling casing. The lengths of each sleeve segmentation 1 can be equal or unequal. When the sleeve segmentations 1 are spliced into a friction-reducing drilling casing, its upper end is connected to the rotary power mechanism, and the lower end extends below the ground, and drills below the ground during continuous rotation.

[0029] Among the several sleeve segmentations 1 that make up the friction-reducing drilling casing, at least a part of the outer surface of the sleeve segmentations 1 is provided with a number of concave grooved channels 2. The sleeve segmentations 1 provided with the grooved channels 2 are in the front of the entire friction-reducing drilling casing, that is, the outer surface of one or several sleeve segmentations 1 in the front is provided with the grooved channels 2. It should be noted that the sizes and shapes of each grooved channel 2 can be the same or different, and the depths can be large or small, and it is not required that all the grooved channels 2 adopt the same size design.

[0030] The casing segment 1 is a cylindrical pipe structure, and the grooved channel 2 is a recessed groove provided on the outer surface of the casing segment 1. The casing segment 1 forms an accommodation space by providing the grooved channel 2. The outer surface of the casing segment 1 is coated with a water-insoluble lubricant, which can be a high-efficiency lubricating oil or grease. Since the grooved channel 2 has a larger accommodation space, more water-insoluble lubricant is accommodated in the grooved channel 2. The lubricant in the grooved channel 2 does not directly contact the wellbore wall during the drilling process, and the lubricant in the grooved channel 2 gradually and slowly releases outward.

[0031] The outer surface of the casing segment 1 contacts the formation during drilling, and the friction is reduced by the lubricant. During the drilling process, the lubricant in the grooved channel 2 continuously releases outward, and a continuous lubrication effect on the outer surface of the casing segment 1 can be achieved. The lubricant used is a low-fluidity lubricant. During the drilling process, the friction temperature between the casing segment 1 and the wellbore wall continuously rises. As the temperature rises, the fluidity of the lubricant increases, and the lubricant continuously flows outward from the grooved channel 2 to reach the outer surface of the casing segment 1 to maintain the lubrication effect.

[0032] It can be seen from this that the anti-friction drilling casing provided by the present invention does not need to continuously transport lubricant downward from the ground during the drilling process. It only needs to coat the outer surface of the casing segment 1 with lubricant once before drilling. A certain amount of lubricant is accommodated in the grooved channel 2, which can maintain the lubrication effect during drilling, and the construction process is more convenient. After the anti-friction drilling casing of the present invention drills to a suitable depth below the ground, the casing remains underground and plays the role of a pipeline.

[0033] On the basis of the above scheme, the present invention limits the size of the grooved channel 2. The depth of the grooved channel 2 does not exceed half of the thickness of the casing segment 1. Generally, the thickness of the entire casing segment 1 wall is evenly distributed along the circumferential direction, but the case where the wall thickness of the casing segment 1 changes along the axial direction is not excluded. The depth of the grooved channel 2 does not exceed half of its position, so as to ensure the structural strength of the casing segment 1. As shown in Figure 5 wherein T represents the thickness of the casing segment 1 and L represents the depth of the grooved channel 2, 2L ≤ T. The grooved channel 2 preferably does not have sharp angles and forms smooth rounded corners to reduce stress concentration. There are various design methods for the depth, width and spacing of the grooved channel. It is necessary to ensure sufficient oil storage space, and at the same time consider the mechanical strength and anti-wear performance of the casing to ensure that while improving the lubrication efficiency, it does not affect the overall stability and service life of the casing.

[0034] In some embodiments, the opening angle of the grooved channel 2 is opposite to the rotation direction of the casing segment 1. As shown in Figure 6 the grooved channel 2 is inclined Figure 6When the casing segment 1 therein rotates clockwise, the opening angle of the grooved slot 2 faces counterclockwise. When the casing segment 1 rotates, it can reduce the scratching of the surface of the grooved slot 2, reduce friction, and can slow down the speed of the lubricant flowing outwards, contributing to achieving a lasting lubrication effect.

[0035] The opening angle of the grooved slot 2 being opposite to the rotation direction of the casing segment 1 is taken as a specific embodiment, but other setting forms are not excluded. Combining Figure 5 As shown, the grooved slot 2 therein is a straight slot opening, and the grooved slot 2 is symmetrically arranged about a certain diameter of the casing segment 1.

[0036] An oil-absorbing resin layer 3 is embedded at the bottom of the grooved slot 2. An oil-absorbing resin material layer is embedded at the bottom of each grooved slot 2 or several of the grooved slots 2. The oil-absorbing resin is a polymer material synthesized by a special process, mainly used for adsorbing and recovering oil products, and has good oil-water separation performance. In the present utility model, by utilizing the high oil-absorbing property and slow release characteristics of the oil-absorbing resin, it can effectively absorb and store lubricating oil or grease, ensure the stable supply of the lubricant, and prevent rapid loss.

[0037] The oil-absorbing resin layer 3 is adhered to the side wall of the casing segment 1 by an adhesive, reducing the probability of falling off during the drilling process.

[0038] 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. The oil-absorbing resin can be designed with a pore structure, has a highly developed specific surface area, and can effectively adsorb and store a large amount of oil. The oil-absorbing resin can be made into various forms. For example, the fabric type is to carry the oil-absorbing resin on a fabric, and its loading amount can be adjusted arbitrarily according to needs. The coating type is to coat the granular solid resin with a non-woven fabric. In some cases, an adhesive needs to be applied between the resin and the casing surface to ensure that the resin is not easily detached during long-term use. Lubricant is evenly applied or injected on the grooves and the oil-absorbing resin. By utilizing the oil-absorbing property of the resin, the lubricating material is continuously and evenly distributed on the contact surface between the casing and the well wall during the drilling process, greatly reducing the friction coefficient.

[0039] Based on any of the above technical solutions and their combinations, the grooved slot 2 adopted in the present utility model is a spiral line, a wavy line or a straight line. Combining Figure 1 、 Figure 2 、 Figure 4 As shown, the length direction of the adopted grooved slot 2 is along the axial direction, and the grooved slot 2 extends in a straight line direction. Combining Figure 3As shown, the length direction of the grooved channel 2 adopted is in a spiral structure, which can be either a clockwise spiral or a counterclockwise spiral. These specific setting forms should all be included within the protection scope of the present utility model. In addition, the design of the grooved channel 2 can also be a combination of a part of a straight line shape and a part of a spiral shape.

[0040] The grooved channel 2 can also have a special geometric shape optimized according to drilling conditions, such as a wavy shape, etc., aiming to increase the contact area between the casing surface and the lubricating material, and at the same time promote the dynamic distribution of the lubricating material during the rotation of the casing. Compared with ordinary casings, these grooved casings can accommodate a larger amount of lubricant after applying lubricating oil or grease.

[0041] Specifically, both ends of the grooved channel 2 extend to the ends of the casing segment 1; or the grooved channels 2 are distributed at intervals along the axial and circumferential directions. Combining Figure 1 、 Figure 2 、 Figure 3 As shown, the grooved channel 2 runs through the entire casing segment 1, both ends of the grooved channel 2 extend to both ends of the casing segment 1, and the length of the grooved channel 2 is greater than or equal to the axial length of the casing segment 1. Combining Figure 4 As shown, it shows the structure in which the grooved channels 2 are distributed at intervals along the axial and circumferential directions. The grooved channels 2 form an array distribution on the outer surface of the casing segment 1, and the length of each grooved channel 2 is shorter than the axial length of the casing segment 1. In addition, the grooved channels 2 can also adopt a form of uneven lengths, some are longer and some are shorter, forming a state of staggered lengths. These specific implementation forms should all be included within the protection scope of the present utility model.

[0042] For the case where both ends of the grooved channel 2 extend to both ends of the casing segment 1, since the grooved channel 2 runs through completely, the lubricant can flow downward along the grooved channel 2, and lubricant can be added from above during the process of drilling downward. For Figure 4 the case where the grooved channels 2 shown are in an array distribution, the lubricant in each grooved channel 2 can be independent of each other, which can avoid the problem of all the lubricant flowing downward.

[0043] Specifically, the lubricant adopted in the present utility model is one or several of lipophilic surfactants, crude oil, mineral oil, machine oil, and grease. According to the temperature, pressure of the drilling environment and the required lubrication performance, a suitable lubricating oil or grease is selected. When the bottom hole temperature is high, a lubricant with a high viscosity is usually selected, and through processes such as spraying and dipping, on the drill floor, while drilling, the lubricant is applied. Crude oil can also be directly used as the lubricant. The crude oil can be ordinary crude oil or heavy oil. The viscosity of heavy oil is greater than that of ordinary crude oil. Ensure that the inside of the grooved channel is fully filled with lubricating material to form a stable lubricating film and reduce the frictional resistance. Waste machine oil can also be used as the lubricating oil.

[0044] Mineral oils and vegetable oils can also be used as lubricants. They have different properties and can be selected according to specific working conditions. Additionally, grease is also a commonly used semi-solid lubricating material, often referred to as "butter". Depending on the base oil, there is a wide variety of grease types available on the market, including calcium-based, sodium-based, lithium-based, complex lithium-based, and bentonite grease, etc. These different types of grease each have their unique performance characteristics and are suitable for different working conditions and requirements.

[0045] The groove 2 has a wedge-shaped cross-section with a smaller opening and a larger bottom or a larger opening and a smaller bottom, or a slotted opening with a consistent width. In combination Figure 1 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 as shown, the groove 2 shown therein has a wedge-shaped cross-section with a larger opening and a smaller bottom, Figure 2 the groove 2 shown has a flared wedge-shaped cross-section with a smaller opening and a larger bottom; the groove 2 can also be a slotted structure with a consistent width at each position, and these specific structures should all be included within the protection scope of the present utility model.

[0046] The present utility model provides a specific operation process herein:

[0047] In the processing stage of the casing segment 1, a series of upper grooves 2 are first engraved on the casing segment 1. The starting ends of these grooves 2 are designed to be in the counterclockwise direction, contrary to the conventional clockwise rotation of drilling operations, with the aim of ensuring that the lubricant can be effectively stored in the grooves during drilling operations.

[0048] During the execution of casing drilling operations, the lubricant is applied to the surface of the casing segment 1 on the drill floor and within the groove 2. The application process of the lubricant can be carried out simultaneously during drilling to maintain a continuous and effective lubrication state. The lubricant mentioned here can be crude oil, but for improving environmental protection standards and operation efficiency, it is recommended to use an automatic coating device to achieve uniform and efficient coating.

[0049] The oil-absorbing resin layer 3 is embedded into the groove 2 using an adhesive. The oil-absorbing resin layer 3 is a polymer material synthesized through a special process, mainly used for adsorbing and recovering oil products, and has good oil-water separation performance. Porous oil-absorbing resin is used. This resin has a highly developed specific surface area through a special pore structure design and can effectively adsorb and store a large amount of oil. The oil-absorbing resin is of the coated type, and the coated type is to coat granular solid resin with non-woven fabric.

[0050] The adhesive used to bond the oil-absorbing resin layer 3 into the grooves on the steel casing is epoxy resin adhesive. Epoxy resin has become the preferred choice for bonding steel and oil-absorbing resin due to its excellent mechanical strength, chemical resistance, and oil resistance. They can be cured at room temperature, and once cured, the formed bonding layer is very tough.

[0051] In actual operation, before applying the adhesive, surface treatment is carried out first, including thoroughly cleaning the grease and oxide layer on the steel surface to ensure the best bonding effect.

[0052] The liquid adhesive is evenly coated on the bottom of the groove 2 through a syringe, and then the oil-absorbing resin is filled in and allowed to cure. After that, the casing segment 1 should be carefully inspected to ensure that the resin layer is uniform and firm.

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

[0054] During the casing drilling process, it can be observed that the value of the frictional resistance is relatively low, indicating that this casing has an obvious lubricating effect. During the drilling operation, as the casing 1 rotates and drills, once it contacts the wellbore, the crude oil located in the groove 2 is squeezed out, forming a lubricating film on both the surface of the casing and the wellbore, thereby effectively reducing the friction between the casing segment 1 and the wellbore.

[0055] As can be seen from the above introduction, the present utility model achieves the lubricating effect by the following means:

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

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

[0058] Application of the oil-absorbing resin layer: In some embodiments, the oil-absorbing resin layer is embedded at the bottom of the groove and fixed by an adhesive. This design further enhances the lubricant storage and slow release mechanism, ensuring the continuous supply of lubricants during long-term operation, reducing maintenance requirements and improving drilling efficiency.

[0059] The specifically designed groove structure on the outer surface of the casing and its application in the water-based drilling fluid environment. The combination technology of the selection of lubricants insoluble in water and the effective storage and release mechanism in the grooves. The oil-absorbing resin layer and its fixing method as an innovation point to enhance the lubrication performance and extend the lubrication cycle. The operation method of applying lubricants while drilling during the drilling process to maintain an efficient lubrication state.

[0060] The anti-friction drilling casing adopting the utility model has the following beneficial effects:

[0061] Significantly reduce resistance: By combining the groove structure with lubricating materials, the friction resistance of the casing during drilling is effectively reduced, the drilling speed is increased, and the energy consumption is reduced. The application of oil-absorbing resin increases the storage time of the lubricant.

[0062] Reduce the wear of the casing caused by friction, especially when the friction resistance is too large, which will damage the threads of the casing connection.

[0063] Strong environmental adaptability: According to different drilling environments and conditions, the types of lubricating materials and groove designs can be flexibly selected and adjusted to improve the universality and adaptability of the technology.

[0064] Simple construction: The groove processing and the coating process of the lubricating material are simple and easy to implement, and are easy to integrate into the existing drilling operation process without major equipment transformation.

[0065] The above description of the disclosed embodiments enables those skilled in the art to implement or use the utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the utility model. Therefore, the utility model will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A friction-reducing drilling casing, characterized in that, It includes several casing segments (1) spliced end to end with each other. On the outer surface of at least a part of the casing segments (1), several sunken groove channels (2) are provided. The outer surface of the casing segments (1) is coated with a water-insoluble lubricant, and the groove channels (2) are used to accommodate the water-insoluble lubricant; the casing segments (1) are used to contact the formation during drilling and reduce friction through the lubricant.

2. The anti-friction drilling casing according to claim 1, characterized in that, The depth of the groove channel (2) does not exceed one-half of the thickness of the casing segment (1).

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

4. The anti-friction drilling casing according to any one of claims 1 to 3, characterized in that, An oil-absorbing resin layer (3) is embedded at the bottom of the groove channel (2).

5. The anti-friction drilling casing according to claim 4, characterized in that, The oil-absorbing resin layer (3) is adhered to the side wall of the casing segment (1) through an adhesive.

6. The anti-friction drilling casing according to claim 5, characterized in that, 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 anti-friction drilling casing according to any one of claims 1 to 3, characterized in that, The groove channel (2) is a spiral line, a wavy line or a straight line.

8. The anti-friction drilling casing according to claim 7, characterized in that, Both ends of the groove channel (2) extend to both ends of the casing segment (1); or the groove channels (2) are distributed at intervals along the axial direction and the circumferential direction.

9. The anti-friction drilling casing according to claim 1, characterized in that, The lubricant is one or several of lipophilic surfactants, crude oil, mineral oil, machine oil, and grease.

10. The antifriction drilling casing according to claim 1, characterized in that, The groove channel (2) has a wedge-shaped cross-section with a small mouth and a large bottom or a large mouth and a small bottom, or a slotted opening with a consistent width.

Images