A drill string assembly resistant to differential pressure sticking

Abstract

The utility model belongs to the field of petroleum drilling technology, concretely relates to a drilling assembly of preventing differential pressure sticking. The utility model discloses heavy drill rod, drill rod, centralizer, drill stand, screw rod and drill bit, heavy drill rod, drill rod, centralizer, drill stand, helical groove screw rod and drill bit are connected from top to bottom in proper order, and the outer side wall of screw rod is provided with helical groove. The utility model can effectively prevent differential pressure sticking caused by well leakage and return and the sticking of drilling caused by overflow water high viscosity high density heavy well mud cake false thickness, avoids the downhole accident, and guarantees the normal operation of complex block construction well of malignant leakage block, advanced water injection heavy block and the like.

Description

Technical Field

[0001] This utility model belongs to the field of oil drilling technology, specifically relating to a drill string assembly that prevents differential pressure sticking. Background Technology

[0002] After several years of continuous research and development, the drilling speed of conventional 81 / 2 wells in shale oil has been increasing year by year, and large-scale speed-up technology has been established. However, the speed-up of unconventional wells (mainly including small wells, three-section wells, deep surface wells, high-viscosity and high-density weighted wells with overflow water in advanced water injection zones, and wells with severe leakage) is relatively slow. The main technical problems that need to be solved include: low mechanical drilling speed and difficulty in trajectory control in the large section of three-section wells; immature drilling fluid matching technology and poor wellbore purification; low sliding speed of small wells; sticking failure during the construction of high-viscosity and high-density weighted wells with overflow water; and pressure differential sticking failure in leakage wells. Therefore, conducting research on unconventional well drilling speed-up technology in complex formations of shale oil in this region is of great significance for improving the overall speed of shale oil production.

[0003] Currently, some shale oil wells in pre-injection water-bearing zones with high viscosity and density of overflowing water, as well as wells with severe leakage, all use a two-stage wellbore structure, employing a 215.9mm drill bit. The drill string assembly consists of: Ø215PDC, Ø172*1.5*210 screw rod, Ø165SDC, Ø210Stab, Ø165NDC, Ø165DC*3, and Ø127Dp (where: PDC is the drill bit; SDC is the short drill collar; Stab is the centralizer; NDC is the non-magnetic drill collar; DC is the drill collar; and Dp is the drill pipe). This assembly provides good stability in inclination and azimuth during construction, and the build-up rate meets design requirements, making it suitable from a trajectory control perspective. However, in areas with severe leakage and pre-injection water-bearing, this drill string assembly is more prone to differential sticking.

[0004] Patent No. CN202123205572.8, "An anti-sticking and wear-resistant drill collar for horizontal and directional wells", includes a drill body, a ladder fixed at the bottom of the drill body, two contact blocks fixed at the bottom of the ladder, a contact ball at the bottom of the ladder and between the two contact blocks, a sliding groove on the ladder, a cutter on the surface of the ladder and between the sliding grooves, a groove at the bottom of the cutter, locking blocks on both sides of the drill body, locking grooves on both sides of the locking blocks, ribs on the surface of the drill body, and a retaining ring on the surface of the drill body and at the bottom of the ribs. This utility model provides an anti-jamming and wear-resistant drill collar for horizontal and directional wells, solving the problem that existing drill collars, when in contact with hard objects during drilling operations, will remain stuck on the surface of the drill collar, causing jamming, severe wear, and affecting the service life of the drill collar. However, it has the following problems: 1. Complex structure: The drill collar surface is designed with jamming blocks, ribs, etc. The drill collar is subjected to complex forces in the well, and the friction between it and the well wall can reach up to 60 tons. The jamming blocks and ribs on the surface can easily fall off and fall into the well, causing downhole accidents; 2. The well wall of the drilled well is not a regular, smooth curved surface, but is generally spiral or irregular circle. Due to the instability of the well wall, it often forms a "bulge". Such jamming blocks can easily get into the "bulge" of the well wall, and the rotational and up-and-down movement of the drill collar can easily disrupt the stability of the well wall. Utility Model Content

[0005] This utility model provides a drill bit assembly for preventing differential pressure sticking, the purpose of which is to provide a drill bit assembly that can effectively prevent sticking accidents.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A drill string assembly for preventing differential pressure sticking includes a weighted drill rod, a drill pipe, a stabilizer, a drill collar, a screw rod, and a drill bit; the weighted drill rod, drill pipe, stabilizer, drill collar, screw rod, and drill bit are connected in sequence from top to bottom; a spiral groove is provided on the outer side wall of the screw rod.

[0007] The pitch of the spiral groove provided on the outer wall of the screw is 30 to 40 centimeters.

[0008] The drill rods used are short drill rods with different lengths ranging from 1 to 3 meters.

[0009] The drill bit has spiral grooves on its sidewall.

[0010] The pitch of the spiral groove on the sidewall of the drill neck is 20-30 cm.

[0011] The weighted drill rod is composed of 20-40 weighted drill rods connected together.

[0012] The drill rod is a non-magnetic, pressure-resistant drill rod.

[0013] The centralizer used is a spiral centralizer.

[0014] The drill neck is a short drill neck with spiral grooves on its sidewall; the drill rod is a non-magnetic, pressure-resistant drill rod; and the centralizer is a spiral centralizer.

[0015] Beneficial effects: This invention designs and processes spiral grooves with a pitch of 30-40 cm on short drill collars and spiral grooves with a pitch of 40-50 cm on the screw body. It uses non-magnetic drill rods instead of commonly used non-magnetic drill collars in the prior art and uses heavy-duty drill rods instead of commonly used drill collars in the prior art. While ensuring the strength of the drill string, the contact area between the drill string and the well wall at the bottom of the well is greatly reduced during sliding drilling. Drilling fluid flow channels are always left around the drill string, which effectively reduces the hydrostatic pressure difference between the drilling fluid in the well and the drill string around the drill string. This avoids the accidental sticking of the drill string due to pressure difference caused by instantaneous leakage on one side of the wellbore. The tools used are commonly used drilling tools, which can be completed with simple processing and assembly. It is simple, practical and effective.

[0016] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings. Attached Figure Description

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

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] In the diagram: 1. Weighted drill pipe; 2. Drill pipe; 3. Centralizer; 4. Drill neck; 5. Screw; 6. Drill bit; 7. Screw body centralizer. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Example 1: according to Figure 1 As shown, a drill string assembly for preventing differential pressure sticking includes a weighted drill rod 1, a drill rod 2, a stabilizer 3, a drill collar 4, a screw rod 5, and a drill bit 6; the weighted drill rod 1, drill rod 2, stabilizer 3, drill collar 4, screw rod 5, and drill bit 6 are connected in sequence from top to bottom; a spiral groove is provided on the outer side wall of the screw rod 5.

[0022] This invention is used during drilling through leaky formations. In actual use, a spiral groove is provided on the outer wall of the screw 5, which leaves a channel between the well wall and the drill string during the drilling process, ensuring pressure balance and effectively preventing differential pressure sticking.

[0023] This invention can effectively prevent pressure differential sticking caused by well leakage and backflow, as well as sticking of the drill bit caused by high viscosity and high density of overflow water increasing the thickness of the mud cake. It avoids downhole accidents and ensures the normal operation of wells in complex blocks such as those with severe leakage and those with pre-injection for weight gain.

[0024] In some embodiments, the pitch of the helical groove provided on the outer side wall of the screw 5 is 30 to 40 centimeters.

[0025] In practical use, the pitch of the spiral groove adopts this technical solution, which can not only effectively prevent the problem of stuck drill bit and avoid downhole accidents, but also ensure that the screw 5 meets the strength requirements, while effectively controlling the processing cost.

[0026] In some embodiments, the drill rod 4 is a short drill rod of different lengths, ranging from 1 to 3 m.

[0027] Furthermore, the drill tap 4 has a spiral groove on its side wall.

[0028] Furthermore, the pitch of the spiral groove on the side wall of the drill tip 4 is 20-30 cm.

[0029] In actual use, the screw 5 is equipped with a screw body centralizer 7. The drill neck 4 uses short drill necks of different lengths from 1 to 3 meters to adjust the distance between the centralizer 3 and the screw body centralizer 7. Combined with the formation's deviation and inclination characteristics, this aims to reduce the proportion of sliding footage, reduce sliding sticking failures, and improve construction efficiency, thereby ensuring the wellbore trajectory conformity rate and wellbore quality standards.

[0030] In some embodiments, the weighted drill rod 1 is composed of 20-40 weighted drill rods connected together.

[0031] In practical use, the weighted drill pipe 1 adopts a technical solution of combining 20-40 drill pipes, which can greatly reduce the contact area between the drill pipe per unit length and the well wall while ensuring the overall strength of the drill string and the weight of the lower drill string.

[0032] In some embodiments, the drill rod 2 is a non-magnetic, pressure-resistant drill rod.

[0033] In actual use, drill pipe 2 adopts the existing non-magnetic pressure-resistant drill pipe. Firstly, it is used to replace the original non-magnetic drill collar. It has steps at both ends and in the middle. The raised structure of the steps is similar to the working principle of the spiral groove, which can effectively prevent differential pressure sticking. Secondly, its weight is 50% less than the original drill collar, which can effectively alleviate the composite descent rate in the lower well section, reduce the slip ratio, reduce slip sticking failure, and improve construction efficiency.

[0034] In some embodiments, the centralizer 3 is a spiral centralizer.

[0035] In actual use, the centralizer 3 adopts a spiral centralizer, which can play a stable supporting role in the high-angle well section and reduce the surface contact to point contact, thus reducing the possibility of sticking.

[0036] In some embodiments, the drill collar 4 is a short drill collar with a spiral groove on its sidewall; the drill rod 2 is a non-magnetic pressure-resistant drill rod; and the centralizer 3 is a spiral centralizer.

[0037] In practical use, the combined use of the weighted drill pipe 1, the drill collar 4 with spiral grooves, the screw 5 with spiral grooves, the non-magnetic pressure-resistant drill pipe 2, the spiral stabilizer, and the drill bit 6 effectively ensures the overall strength of the drill string and the weight of the lower drill string while significantly reducing the contact area between the drill string per unit length and the wellbore. The spiral stabilizer provides stable support in high-angle well sections, reducing surface contact to point contact. The design and fabrication of short drill collars and screw 5 with spiral grooves leaves a channel between the wellbore and the drill string, ensuring pressure balance and effectively preventing differential sticking.

[0038] Example 2: according to Figure 1 The image shows a specific application example of a drill string assembly designed to prevent differential pressure sticking.

[0039] A drilling platform deployed 8 directional gas wells with an average designed well depth of 3400 meters and an average horizontal displacement of 1500 meters. Two wells experienced three instances of drill string sticking, resulting in a loss of 845 hours and an economic loss of 2.4 million yuan. The drill string combination used in the two wells experiencing sticking was: Ø215PDC, Ø172*1.5*210 screw rod, Ø165SDC, Ø210Stab, Ø165NDC, 3 Ø165DC rods, and Ø127Dp. Subsequent wells used an optimized combination: Ø215PDC, Ø172*1.5*210 screw rod (with helical grooves), Ø165SDC (1-3m), Ø210Stab, 2 Ø165NDp rods, 30 Ø127HWDp rods, and Ø127Dp, all of which were successfully completed. In the above: PDC is drill bit; SDC is short drill collar; Stab is centralizer; NDp is non-magnetic drill pipe; HWDp is weighted drill pipe; Dp is drill pipe.

[0040] The implementation of this method is as follows: (a) Construction well 1 Well No. 1 was drilled to a depth of 2370 meters in the Liujiagou formation when drilling fluid loss occurred. The drill string had no room to move up or down and could not rotate, resulting in stuck drill string. 20 cubic meters of plugging slurry were prepared and pumped in, successfully sealing the leak. The slurry returned to the outlet, and normal flow circulation showed no leakage, indicating the drill string was stuck. After back-threading, milling, and tremor treatment, the stuck drill string was released. The drill string was then pulled out and replaced with a pressure differential-resistant stuck drill string assembly, and drilling continued. During this period, 15 well leaks occurred at depths of 2422 meters, 2427 meters, 2446 meters, 2456 meters, 2471 meters, 2478 meters, 2485 meters, 2495 meters, 2507 meters, 2514 meters, 2525 meters, 2543 meters, 2581 meters, 2764 meters, and 2786 meters. No pressure differential stuck failures caused by well leaks occurred. Drilling was successfully completed at a depth of 3483 meters.

[0041] (ii) Construction well 2 For Well 2, the second drilling operation directly used a drill string assembly designed to prevent differential pressure sticking. The well was drilled to depths of 2028 meters, 2311 meters, 2449 meters, and 2949 meters. There were four instances of well leakage, but no differential pressure sticking failures caused by well leakage occurred, and the drilling was successfully completed.

[0042] (III) Construction Well 3 In well 3, the second drilling operation directly used a drill string assembly designed to prevent differential pressure sticking. The wells were drilled to depths of 2228 meters, 2286 meters, 2323 meters, 2426 meters, and 2753 meters. There were a total of 5 well leaks, but no differential pressure sticking failures caused by well leaks occurred, and the drilling was successfully completed.

[0043] Usage results: A drilling platform deployed six directional gas wells. Three wells were completed in 2023 (with two instances of differential pressure sticking), and three more were completed in 2024 (with one instance of differential pressure sticking). After using a drill string assembly designed to prevent differential pressure sticking, no stuck drill string occurred in the following situations: 15 instances of lost circulation occurred in the lower 1110-meter section of well 1-6; 4 instances occurred throughout the entire section of well 1-7; and 5 instances occurred throughout the entire section of well 1-8. This drill string assembly demonstrated significant effectiveness in preventing differential pressure sticking caused by lost circulation.

[0044] In the past five years, 89 overflow incidents occurred in the pre-injection blocks, representing an incidence rate of 6.4%. The average well control density was 1.49 g / cm³. 3 The highest well-killing density is 1.96 g / cm³. 3 In 2021, four overflow wells in the Wangyao 160 advanced water injection zone experienced stuck drilling, resulting in a total loss of 360 hours and economic losses of approximately 2.8 million yuan. Among them, well Wangjiaping 43-0291, at a depth of 1681 meters, experienced stuck drilling during the sliding process, with a drilling fluid density of 1.57 g / cm³. 3 The drilling fluid viscosity was 55S. It was first soaked in potassium chloride solution, then shocked using a shredder, followed by high-volume circulation of caustic soda solution, then soaked in diesel and acid solutions, with intermittent drilling of the drill string to release the stuck drill string. Later, all five well sites were replaced with anti-pressure differential sticking drill string assemblies, and 29 more wells were drilled without any sticking failures. The project was successfully completed.

[0045] Usage results: During the initial construction phase of the Wangyao advanced water injection zone project using conventional drilling rigs, four wells experienced stuck drill bit failure. After switching to a pressure differential-resistant stuck drill bit assembly, the remaining 29 wells were successfully drilled. This drilling rig assembly also proved effective in the construction of high-viscosity, high-density weighted wells with overflow water.

[0046] Where there is no conflict, those skilled in the art can combine the relevant technical features in the above examples according to the actual situation to achieve the corresponding technical effects. Specific details of the various combinations will not be elaborated here.

[0047] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0048] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0049] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Any simple modifications, equivalent variations, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the present invention.

Claims

1. A drill string assembly for preventing differential pressure sticking, characterized in that: It includes a weighted drill rod (1), a drill rod (2), a stabilizer (3), a drill collar (4), a screw rod (5), and a drill bit (6); the weighted drill rod (1), the drill rod (2), the stabilizer (3), the drill collar (4), the spiral groove screw rod (5), and the drill bit (6) are connected in sequence from top to bottom; a spiral groove is provided on the outer side wall of the screw rod (5); The pitch of the spiral groove provided on the outer wall of the screw (5) is 30-40 cm; The drill rod (4) is a short drill rod of different lengths, ranging from 1 to 3 m. The drill neck (4) has a spiral groove on its side wall; The pitch of the spiral groove on the side wall of the drill neck (4) is 20-30 cm.

2. The drill string assembly for preventing differential pressure sticking as described in claim 1, characterized in that: The weighted drill rod (1) is composed of 20-40 weighted drill rods connected together.

3. The drill string assembly for preventing differential pressure sticking as described in claim 1, characterized in that: The drill rod (2) is a non-magnetic pressure-resistant drill rod.

4. The drill string assembly for preventing differential pressure sticking as described in claim 1, characterized in that: The centralizer (3) is a spiral centralizer.

5. The drill string assembly for preventing differential pressure sticking as described in claim 1, characterized in that: The drill neck (4) is a short drill neck with a spiral groove on its side wall; the drill rod (2) is a non-magnetic pressure-resistant drill rod; the stabilizer (3) is a spiral stabilizer.

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