阅读说明：本技术 钻压控制式井下循环短接及连续管钻塞动态冲洗工艺 (Drilling pressure control type underground circulation short circuit and coiled tubing drill plug dynamic flushing process ) 是由 郭晓乐 张迪盛 岳凡钦 刘继林 于 2020-03-16 设计创作，主要内容包括：本发明公开了一种钻压控制式井下循环短接及连续管钻塞动态冲洗工艺,其中循环短接包括通过弹性元件滑动配合的上接头体和下接头体,上接头体的侧壁下端具有过流孔,下接头体与上接头体之间具有前喷流道和侧喷流道,下接头体能够沿上接头体的轴向滑动,以使过流孔择一与前喷流道或侧喷流道连通,下接头体侧壁上具有侧喷孔,侧喷孔朝上倾斜设置；钻磨工艺主要采用了循环短接,在确定合理钻压参数后进行钻磨操作,并通过优化的侧向射流结构、排量和管柱上提速度进行动态冲洗磨屑上返,最后重复钻磨循环直至完成全部作业。短接整体结构巧妙,使用寿命长,便于操作,本工艺有利于提高磨屑冲洗效果,提高连续管钻塞效益,以及促进该技术的应用推广。(The invention discloses a drilling pressure control type underground circulation short circuit and a dynamic flushing process of a coiled tubing drill plug, wherein the circulation short circuit comprises an upper joint body and a lower joint body which are in sliding fit through an elastic element, the lower end of the side wall of the upper joint body is provided with an overflowing hole, a front spray flow channel and a side spray flow channel are arranged between the lower joint body and the upper joint body, the lower joint body can slide along the axial direction of the upper joint body so as to enable one of the overflowing holes to be communicated with the front spray flow channel or the side spray flow channel, the side wall of the lower joint body is provided with a side spray hole, and the side spray hole is arranged upwards; the drilling and grinding process mainly adopts a circulation short circuit, drilling and grinding operations are carried out after reasonable drilling pressure parameters are determined, dynamic flushing abrasive dust upward return is carried out through an optimized lateral jet flow structure, discharge capacity and pipe column lifting speed, and finally drilling and grinding circulation is repeated until all operations are completed. The short circuit overall structure is ingenious, long service life, the operation of being convenient for, and this technology is favorable to improving the abrasive dust washing effect, improves coiled tubing and bores the stopper benefit to and promote the application popularization of this technique.)

1. The utility model provides a weight-on-bit control formula circulation short circuit in pit which characterized in that: the joint comprises an upper joint body (1) and a lower joint body (2) which are both in a hollow tubular structure, wherein the lower joint body (2) is coaxially sleeved on the lower part of the upper joint body (1) in a movable mode through an elastic element (3) and surrounds the upper joint body (1) to form a front spray channel (4) and a side spray channel (5) which are mutually isolated, a side spray hole (20) communicated with the side spray channel (5) is formed in the side wall of the lower joint body (2), the side spray hole (20) is arranged in an upward inclined mode, and the lower joint body (2) can axially slide relative to the upper joint body (1) under the action of external force;

the lower end of the upper joint body (1) is sealed through the plugging structure (11), an overflowing hole (12) is formed in the side wall close to the lower end, and when the lower joint body (2) slides, the overflowing hole (12) can be selectively communicated with the front spray flow channel (4) or the side spray flow channel (5).

2. The weight-on-bit controlled downhole circulation sub of claim 1, wherein: the upper joint body (1) comprises a connecting end (13), an inner cylinder (14) and an outer cylinder (15) which are integrally formed, an upper isolation disc (23) and a lower isolation disc (24) are arranged in the lower joint body (2) along the radial direction of the lower joint body, the upper isolation disc (23) and the lower isolation disc (24) are tightly attached to the side wall of the inner cylinder (14), and a dynamic sealing structure is correspondingly arranged;

the space between the upper partition plate (23) and the lower partition plate (24) and the inner cylinder (14) form the side spray flow channel (5), and the space at the lower part of the lower partition plate (24) and the inner cylinder (14) form the front spray flow channel (4).

3. The weight-on-bit controlled downhole circulation sub of claim 2, wherein: go up and be equipped with spacing guide structure between joint body (1) and lower joint body (2) for it produces relative rotation to restrict to go up joint body (1) and lower joint body (2).

4. The weight-on-bit controlled downhole circulation sub of claim 3, wherein: spacing guide structure is including evenly distributed boss (150) on urceolus (15) outer wall, boss (150) set up along the length direction of urceolus (15), lower joint body (2) upper end inboard have with boss (150) complex recess (210).

5. The weight-on-bit controlled downhole circulation sub of claim 2, wherein: the elastic element (3) is a spiral spring or a disc spring, the spiral spring or the disc spring is positioned between the inner cylinder (14) and the outer cylinder (15), and the upper end and the lower end of the spiral spring or the disc spring are respectively abutted with the upper end of the inner cylinder (14) and the upper isolation disc (23).

6. The weight-on-bit controlled downhole circulation sub of claim 2, wherein: lower joint body (2) are including connecting upper segment (21) and connecting hypomere (22) that link to each other with the mode of dismantling, go up and seal partition dish (23) and connect upper segment (21) integrated into one piece, lower seal partition dish (24) and connect hypomere (22) integrated into one piece, side orifice (20) are located and connect upper segment (21), the lower extreme that connects hypomere (22) has the internal thread.

7. The weight-on-bit controlled downhole circulation sub of claim 2, wherein: the plugging structure (11) is a plug, the diameter of the plug is larger than the inner diameter of the lower packer disc (24), and the plug is fixedly connected with the inner cylinder (14) in a welding or threaded connection mode.

8. The weight-on-bit controlled downhole circulation sub of claim 1, wherein: the side spray hole (20) is internally threaded on the side wall.

9. The dynamic flushing process for the coiled tubing drill plug is characterized in that a drilling tool assembly at least comprises a mill shoe, the drill pressure control type underground circulation pup joint, a motor, a coiled tubing connector and a coiled tubing which are sequentially connected with one another through threads from bottom to top, and the dynamic flushing process is carried out according to the following steps:

firstly, determining reasonable drilling pressure parameters according to the physical properties of the bridge plug, the elastic coefficient of the elastic element (3) and the sliding stroke of the lower adapter body (2);

secondly, optimizing the drilling and grinding discharge capacity and the aperture of a side nozzle to be installed in a side jet hole (20) according to the size of the well hole and the drilling tool assembly, and performing drilling and grinding operation according to reasonable drilling pressure parameters;

and thirdly, after N bridge plugs are drilled and ground, lifting the drilling tool to enable the elastic element (3) to be in a reset state, communicating the overflowing hole (12) with the side jet flow channel (5), optimizing the discharge capacity and the pipe column lifting speed according to the aperture of the side jet nozzle and the ground rated pump pressure, circulating by adopting the optimized discharge capacity, and lifting the drilling tool at the optimized speed.

And fourthly, repeating the second step and the third step until the bridge plug drilling and grinding is completed.

10. The coiled tubing drill plug dynamic flushing process of claim 9, wherein: and the N is determined by the maximum discharge capacity of the pump, the maximum lifting speed of the pipe column and the drilling and grinding speed, and is corrected by comparing the theoretical calculated chip return quantity with the actual wellhead chip return quantity.

Technical Field

The invention relates to the technical field of oil and gas well development, in particular to a drilling pressure control type underground circulation short circuit and coiled tubing drill plug dynamic flushing process.

Background

In recent years, with the large-scale development of shale gas and compact low-permeability oil and gas reservoirs at home and abroad, the drillable bridge plug segmented multi-cluster fracturing of the horizontal well is widely applied. The technology forms a complex fracture network system through cluster perforation and layered fracturing, improves the seepage rate of a reservoir, and has obvious effect on yield increase modification of shale gas and compact low-permeability oil and gas reservoirs. After the fracturing construction of all intervals is completed, the continuous pipe is adopted to carry a milling tool to drill and mill residual bridge plugs in the shaft, so that the construction efficiency can be improved, the production cost can be saved, the detention time of drilling and plugging working fluid in the shaft can be shortened, and the damage to the reservoir is reduced.

The prior drilling and plugging process for the coiled tubing at home and abroad comprises the following steps: after drilling and grinding a plurality of bridge plugs, lifting the bridge plugs to a certain position or not lifting the continuous pipe, flushing plug drilling liquid from the water holes of the grinding shoes in the positive direction, returning the bridge plugs upwards by carrying abrasive dust through annular space as shown in the attached drawing 11, and repeating the process until all bridge plugs are drilled and ground completely. Even so, under many circumstances, especially highly deviated well section, still can some abrasive dust normally return out, lead to the scene to be compelled to lift the transfer tubular column many times, increase the tired harm degree of tubular column and warp, the sticking of bore risk, or adopt strong magnetic tool to salvage, increase activity duration and cost. Therefore, the application and popularization of the coiled tubing drilling and grinding bridge plug technology are greatly restricted.

Disclosure of Invention

In order to solve the problems, the invention provides a bit pressure control type underground circulation short circuit and a continuous pipe drill plug dynamic flushing process, which can effectively improve the upward return speed and circulation effect of abrasive dust, greatly reduce the lifting times and operation time of a pipe column, reduce the fatigue degree and underground risk of a continuous pipe and improve the drill plug benefit of the continuous pipe.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the utility model provides a weight-on-bit control formula circulation short circuit in pit which the key lies in: the lower joint body is coaxially sleeved at the lower part of the upper joint body through an elastic element and surrounds the upper joint body to form a front spray flow channel and a side spray flow channel which are mutually isolated, a side spray hole communicated with the side spray flow channel is arranged on the side wall of the lower joint body, the side spray hole is arranged in an upward inclined manner, and the lower joint body can axially slide relative to the upper joint body under the action of external force;

the lower end of the upper joint body is sealed through the plugging structure, an overflowing hole is formed in the side wall close to the lower end, and when the lower joint body slides, the overflowing hole can be selectively communicated with the front spray flow channel or the side spray flow channel.

By adopting the scheme, when the lower joint body bears pressure, the elastic element is in a compression state, the front jet flow channel is communicated with the overflowing hole, drilling fluid in the drilling tool completely passes through the front jet flow channel and even is injected into the shaft bottom by the lower drilling tool, when the lower joint body is in a suspension state, the elastic element is in a reset state, the side jet flow channel is communicated with the overflowing hole, and meanwhile, because the lower end of the main flow channel (the inner cavity of the upper joint body) is sealed, the drilling fluid in the drilling tool is completely upwards and obliquely jetted to the annular space through the side jet hole, so that the jet impact force and the upward return speed of abrasive dust are greatly improved, the back-discharge efficiency of the abrasive dust of the bridge plug is improved, the drilling pressure.

Preferably, the method comprises the following steps: the upper joint body comprises an integrally formed connecting end, an inner cylinder and an outer cylinder, an upper packer disc and a lower packer disc are arranged in the lower joint body along the radial direction of the lower joint body, the upper packer disc and the lower packer disc are tightly attached to the side wall of the inner cylinder, and a dynamic sealing structure is correspondingly arranged;

the space between the upper packing partition plate and the lower packing partition plate and the inner cylinder form the side spraying flow passage, and the space below the lower packing partition plate and the inner cylinder form the front spraying flow passage. The design of the inner cylinder and the outer cylinder is adopted, the integral strength of the upper joint can be effectively improved, the stability of the lower joint body during sliding is effectively improved, and meanwhile, the dynamic sealing structure is favorable for ensuring the pressure stability inside the overflow hole when the overflow hole is communicated with the side jet flow channel, so that the situation that the fluid enters the front jet flow channel or is not limited by the side jet hole to influence the jet flow speed is avoided.

Preferably, a limiting guide structure is arranged between the upper joint body and the lower joint body and used for limiting the upper joint body and the lower joint body to rotate relatively. By adopting the scheme, the reliability of the lower joint body in sliding relative to the upper joint body can be ensured, the torsion resistance of the lower joint body and the upper joint body in integral application can be improved, the two joint bodies are ensured to integrally rotate without relative rotation, the power transmission of the upper part can be realized, and the rotating speed of the bottom milling shoe can not be influenced.

Preferably, the method comprises the following steps: spacing guide structure includes evenly distributed's boss on the urceolus outer wall, the boss sets up along the length direction of urceolus, lower adapter body upper end inboard have with boss complex recess. By adopting the scheme, the structure is simple and reliable, and the production and processing cost is reduced.

Preferably, the method comprises the following steps: the elastic element is a spiral spring or a disc spring, the spiral spring or the disc spring is positioned between the inner cylinder and the outer cylinder, and the upper end and the lower end of the spiral spring or the disc spring are respectively abutted with the upper end of the inner cylinder and the upper packing disc. By adopting the structure, the elastic element is arranged between the inner barrel and the outer barrel, and the outer barrel can effectively isolate shaft bottom return scraps from entering the installation space of the elastic element, so that the influence on the normal expansion of the elastic element is avoided, and the normal service life of the elastic element is prolonged.

Preferably, the method comprises the following steps: the lower joint body comprises a joint upper section and a joint lower section which are connected in a detachable mode, the upper sealing disc and the joint upper section are integrally formed, the lower sealing disc and the joint lower section are integrally formed, the side spray hole is positioned on the joint upper section, and the lower end of the joint lower section is provided with an internal thread. Adopt split type lower adapter body, be favorable to improving holistic assemblability, maintainability and suitability, because the adopted mill shoe size is different to different well sizes usually, then the connector link of mill shoe also can change thereupon, still adopt integral type lower adapter body so, then need dispose multiple knot type, and adopt split type lower adapter body, then only dispose the joint hypomere of a plurality of different knot types, and connect the hypomere and connect adopt general knot type to be connected between the upper segment can, in addition, when the side jet orifice damages, also only need change the joint upper segment can, reduce use cost relatively.

Preferably, the method comprises the following steps: the plugging structure is a plug, the diameter of the plug is larger than the inner diameter of the lower plugging disc, and the plug is fixedly connected with the inner barrel in a welding or threaded connection mode. By adopting the scheme, the lower stop position of the sliding stroke of the lower joint body is limited by the plug, so that the lower joint body can be effectively prevented from falling off from the upper joint body, and the underground use safety factor of the lower joint body is improved.

Preferably, the method comprises the following steps: the side spray hole side wall is provided with an internal thread. By adopting the scheme, the nozzles with different sizes can be installed in the side spray holes as required to adjust the parameters such as spray pressure, speed and the like, the application range of the same short circuit is enlarged, meanwhile, the jet speed at the nozzle is high, the jet part belongs to a vulnerable part, and after the short circuit is damaged, the nozzle is only required to be replaced, and the short section is not required to be detached.

On this basis, this application has still provided a coiled tubing drill plug developments washing technology, and its key lies in, adopts the drilling tool combination to include at least mill shoe, above-mentioned weight-on-bit control formula circulation short circuit in pit, motor, coiled tubing joint and the coiled tubing that loops through screw interconnect from the bottom up to carry out according to following step:

firstly, determining reasonable drilling pressure parameters according to the physical properties of the bridge plug, the elastic coefficient of the elastic element and the sliding stroke of the lower adapter body;

secondly, optimizing the drilling and grinding discharge capacity and the aperture of a side nozzle needing to be installed in a side nozzle according to the sizes of the well hole and the drilling tool assembly, and performing drilling and grinding operation according to reasonable drilling pressure parameters;

and thirdly, after N bridge plugs are drilled and ground, lifting the drilling tool to enable the elastic element to be in a reset state, enabling the overflowing hole to be communicated with the side jet flow channel, optimizing the discharge capacity and the pipe column lifting speed according to the aperture of the side jet nozzle and the ground rated pump pressure, circulating by adopting the optimized discharge capacity, and lifting the drilling tool at the optimized speed.

And fourthly, repeating the second step and the third step until the bridge plug drilling and grinding is completed.

By adopting the scheme, the drilling grinding or circulating reverse arrangement operation is completed in a matching way by introducing the circulating short circuit according to the relative position of the lower joint body and the upper joint body under the control of applied bit pressure and the communication state of the overflowing hole, the front jet flow channel and the side jet flow channel, and the circulating reverse arrangement is realized by simultaneously lifting the drilling tool and matching with the optimized discharge capacity and lifting speed, so that the whole abrasive dust can be cleaned by lifting once theoretically, the lifting times and the operation time of the pipe column can be greatly reduced, the fatigue degree and the underground risk of the coiled tubing are reduced, and the drilling plug benefit of the coiled tubing is improved. The device can greatly improve the chip removal efficiency of the shaft, avoid abrasive dust accumulation, reduce the operation time and the underground risk, contribute to the application and the popularization of the coiled tubing drilling and grinding bridge plug technology, and promote the progress of the oil and gas exploitation technology.

Preferably, the method comprises the following steps: and the N is determined by the maximum discharge capacity of the pump, the maximum lifting speed of the pipe column and the drilling and grinding speed, and is corrected by comparing the theoretical calculated chip return quantity with the actual wellhead chip return quantity. By adopting the scheme, the abrasive dust washing efficiency is high, the quantity or the interval time of the single-operation drilling and grinding bridge plugs can be obviously greater than that of the conventional drilling and grinding operation, the N value is scientifically determined by combining theoretical calculation according to the actual situation on site, the drilling and grinding efficiency is favorably improved, and the operation cost and time are reduced.

Compared with the prior art, the invention has the beneficial effects that:

by adopting the bit pressure control type underground circulation pup joint and the continuous pipe drill plug dynamic flushing process, the opening and closing of the side spray holes can be realized by controlling the bit pressure, no additional operation control is needed, the operation difficulty is greatly reduced, the circulation pup joint can well transmit the upper power torque, the whole structure is simple, the processing, the assembly and the maintenance are easy, and the service life is long.

The method has the advantages that the optimized discharge capacity and the measured jet flow matched with the lifting mode of the drilling tool pipe column are adopted for flushing abrasive dust, the upward returning speed of the bridge plug abrasive dust and the bridge plug drilling and grinding efficiency can be greatly improved, the drilling and plugging construction operation time and risk are greatly reduced, the drilling and plugging benefits of the coiled tubing are improved, and the application and popularization of the technology for drilling and grinding the bridge plug of the coiled tubing are particularly facilitated.

Drawings

FIG. 1 is an exploded view of the structure of the present invention;

FIG. 2 is a schematic structural view of the present invention when the elastic element is in a reset state;

FIG. 3 is a cross-sectional view of FIG. 2;

FIG. 4 is a schematic structural view of the present invention when the elastic element is in a pressurized state; (ii) a

FIG. 5 is a cross-sectional view of FIG. 4;

FIG. 6 is a schematic structural diagram of an upper section of a joint;

FIG. 7 is a schematic view of the structure of the lower section of the joint;

FIG. 8 is a graph comparing the effect of a side nozzle on bridge plug swarf up-flow velocity;

FIG. 9 is a schematic diagram showing the comparison of jet velocities of lateral nozzles with different apertures;

FIG. 10 is a schematic view of the dynamic flushing of swarf in the drilling and grinding process of the present invention;

fig. 11 is a schematic view of conventional drill grinding process fluid flushing swarf.

Detailed Description

The present invention will be further described with reference to the following examples and the accompanying drawings.

Referring to fig. 1 to 10, a weight-on-bit controlled downhole circulation pup joint and a coiled tubing drill plug dynamic flushing process are shown, wherein the weight-on-bit controlled downhole circulation pup joint mainly comprises an upper joint body 1 and a lower joint body 2 which are both generally hollow tubular structures, the upper joint body 1 and the lower joint body 2 are movably connected relatively, namely, the upper joint body and the lower joint body can slide relatively along an axis, an elastic element 3 is arranged between the upper joint body and the lower joint body, the elastic element 3 is mainly used for assisting the upper joint body and the lower joint body to recover to the original position when in a non-pressure-bearing state, and the upper end of the upper joint body 1 and the lower end of the lower.

The upper joint body 1 mainly comprises a connecting end 13, an inner cylinder 14 and an outer cylinder 15, as shown in fig. 1 and fig. 3, the connecting end 13, the inner cylinder 14 and the outer cylinder 15 are integrally formed, an internal thread for connecting with an upper drilling tool is arranged on the connecting end 13, and the outer diameters of the connecting end 13, the outer cylinder 15 and the inner cylinder 14 are gradually reduced, so that a step 16 is formed between the outer cylinder 15 and the connecting end 13, a hollow part of the inner cylinder 14 forms a main flow passage 10 communicated with the upper drilling tool, a blocking structure 11 is arranged at the lower end of the inner cylinder 14, the lower end of the main flow passage 10 is sealed through the blocking structure 11, overflowing holes 12 uniformly distributed along the circumferential direction of the lower end of the inner cylinder 14 are formed in the lower end of the inner cylinder 14, and.

The lower joint body 2 is basically movably sleeved on the inner cylinder 14, a front spray channel 4 and a side spray channel 5 are respectively formed between a sealing structure arranged in the lower joint body and the inner cylinder 14, the sealing structure is positioned between a step 16 and a blocking structure 11, namely, the sliding stroke of the lower joint body 2 is limited by the step 16 and the blocking structure 11, meanwhile, a side spray hole 20 is arranged on the lower joint body 2 corresponding to the side spray channel 5, the side spray holes 20 are uniformly distributed along the circumferential direction of the lower joint body 2, it needs to be noted that the distance between the overflowing hole 12 and the lower edge of the inner cylinder 14 is smaller than the sliding stroke of the lower joint body 2, namely, when the lower joint body 2 has no reaction pressure and is only under the acting force of the elastic element 3, the overflowing hole 12 is communicated with the side spray channel 5, at the moment, all fluid in the main flow channel 10 enters the side spray channel 5 and enters the downhole annular space through the side spray hole 20, otherwise, when the lower joint body, when the elastic element is compressed, the overflowing hole 12 can be communicated with the front jet channel 4, and the fluid in the main channel 10 completely enters the front jet channel 4.

Of course, in order to ensure that the fluid has a good auxiliary reverse-discharging effect when entering the annular space through the side nozzle holes 20, the side nozzle holes 20 are arranged to be inclined upward as a whole in the present application, that is, the outer ends of the side nozzle holes 20 are higher than the inner ends.

The packing structure mainly comprises an upper packing disc 23 and a lower packing disc 24 which are both in annular disc structures, the inner diameters of the upper packing disc 23 and the lower packing disc 24 are both adapted to the inner cylinder 14, the inner walls of the upper packing disc 23 and the lower packing disc 24 are clung to the circumferential side wall of the inner cylinder 14 after the assembly is finished, the upper packing disc 23 and the lower packing disc 24 are distributed up and down, the height space between the upper packing disc 23 and the lower packing disc 24 is equal to the side wall of the inner cylinder 14, and the inner wall corresponding to the lower joint body 2 surround to form the side jet channel 5, correspondingly, the lower space of the lower sealing disc 24 and the inner cylinder 14 form the front jet channel 4, meanwhile, in order to improve the relative independence of the front jet flow passage 4 and the side jet flow passage 5, a dynamic sealing structure is arranged between the upper packing partition plate 23 and the lower packing partition plate 24 and the inner cylinder 14, in the embodiment, adopt the mode of inlaying the sealing ring 6 of establishing at the both circumference inboards to seal, its structural cost is lower relatively, and the later stage of being convenient for is changed.

Because the synchronous movement or synchronous stop of the upper joint body 1 and the lower joint body 2 is required to be ensured in the using process so as to achieve the purpose of power transmission, a limit guide structure which is matched with each other is arranged between the upper joint body 1 and the lower joint body 2, specifically referring to fig. 1, 3 and 6, the outer wall of the outer cylinder 15 is provided with bosses 150 which are uniformly distributed along the circumferential direction thereof, the bosses 150 extend along the length direction of the outer cylinder 15, and the inner side of the upper end of the lower joint body 2 is provided with a groove 210 which is matched with the bosses 150, therefore, it is required to be noted that the length of the outer cylinder 15 is larger than the sliding stroke of the lower joint body 2, even if the elastic element 3 is in a reset state, an overlapped part still exists between the outer cylinder 15 and the lower joint body 2, the bosses 150 and the corresponding grooves 210 in the overlapped part are always in a matched state, so as to ensure that the power torque, and the two can not relatively rotate, and in addition, the design of the limiting and guiding structure can also improve the stability and the reliability of the lower joint body 2 during axial sliding.

In addition, in order to improve the reliability of torque transmission in the present application, the length design of the outer cylinder 15, the distance between the upper edge of the lower joint body 2 and the upper edge of the upper packing disc 23, the position of the lower packing disc 24 and the size design of the blocking structure 11 need to satisfy the following relationship, that is, when the lower joint body 2 bears pressure and the upper edge of the lower joint body 2 is tightly attached to the step 16 after compressing the elastic element 2, the lower edge of the outer cylinder 15 is just tightly attached to the upper surface of the upper packing disc 23, and in the embodiment using the circular plug as the blocking structure 11, the diameter of the circular plug is larger than the inner diameter of the lower packing disc 24, and when the elastic element 3 is in the reset state, the lower surface of the lower packing disc 24 can just be tightly attached to the upper surface of the circular plug.

The plug and the inner barrel 14 can be fixedly connected by welding or screwing, the welding is firmer, the screwing is more convenient for later-stage disassembly and maintenance, and other connection modes can be selected according to actual needs.

The elastic element 3 in the present application may be a coil spring or a disc spring, and in this embodiment, a high-strength coil spring is preferably used and disposed between the inner cylinder 14 and the outer cylinder 15, as shown in fig. 3 and 5, when the device is installed, the upper end of the coil spring may be fixed on the end surface between the inner cylinder 14 and the outer cylinder 15, and the lower end of the coil spring is tightly attached to the upper surface of the upper packing disc 23, and of course, a coil spring limiting ring groove may be disposed at a corresponding position on the upper packing disc 23 as required to improve the limitation of the coil spring, and prevent the coil spring from shifting or compressing and twisting during use.

Lower adapter body 2 in this application can adopt integral type casting structure, also can adopt split type detachable construction, take split type detachable construction as an example, it mainly includes joint upper segment 21 and joint hypomere 22 through the thread connection, as shown in fig. 1, fig. 3, fig. 5, fig. 6 and fig. 7, go up and seal the partition dish 23 and connect upper segment 21 integrated into one piece, and seal the partition dish 24 down then with connect hypomere 22 integrated into one piece, the lower extreme that connects hypomere 22 has the internal thread, side jet hole 20 is constructed on connecting upper segment 21, adopt this kind of split type structure, the local change in later stage of mainly being convenient for, or with sub-unit connection drilling tool collocation, cost reduction etc.

In order to further expand the application condition of the circulation short circuit, internal threads are processed on the side wall of the side spray hole 20 for installing nozzles with different sizes, so that the speed adjusting range of the lateral jet flow can be effectively expanded.

In view of the above-mentioned drilling pressure control type downhole circulation short circuit, the present application provides a coiled tubing drill plug dynamic flushing process, which mainly adopts the above-mentioned circulation short circuit, the drilling tool assembly at least comprises a mill shoe, a circulation short circuit, a motor, a coiled tubing joint and a coiled tubing which are sequentially connected by screw thread from bottom to top, and some necessary downhole tools connected according to actual conditions, for example, in order to improve the safety, a jar, a hydraulic release and other drilling tools are connected above the motor, the general steps are as follows;

firstly, determining reasonable drilling pressure parameters according to the physical properties of the bridge plug, the elastic coefficient of the elastic element 3 and the sliding stroke of the lower joint body 2, wherein the bridge plug is made of a composite material generally, the actual drilling size can be influenced by overlarge or undersize drilling pressure, and meanwhile, when the drilling pressure is given, overlarge drilling pressure is required to be avoided to cause overlarge axial pressure between the upper joint body and the lower joint body, the upper joint body and the lower joint body are in an overload state for a long time, and the like, so that the circulating short joint is ensured to be in an optimal working position, and the common on-site drilling pressure completely meets the use requirement.

And secondly, optimizing the drilling and grinding discharge capacity and the aperture of the side jet hole 20 (when a side jet nozzle is installed in the side jet hole 20, the aperture of the side jet nozzle is the aperture of the side jet nozzle) according to the size, the well depth and the like of the well hole and the drilling and grinding combination, and performing drilling and grinding operation according to reasonable drilling pressure parameters, wherein the drilling pressure and the discharge capacity are optimized by the same method as the conventional drilling and grinding process optimization method, the aperture of the side jet hole 20 (the side jet nozzle) is optimized according to the maximum jet impact force mode during the lifting circulation, and the method is similar to the method for optimizing the size of.

Thirdly, after drilling and grinding N bridge plugs (N is usually a natural number larger than 0, and mainly aims at a bridge plug under a shale gas well, the bridge plug is provided with a plurality of bridge plugs, and for other cases, the time and the footage variable can be taken as references), the lifting drilling tool enables the elastic element 3 to be in a reset state (whether the elastic element 3 is in the reset state can be determined according to the rechecking suspension weight), the communication between the overflowing hole 12 and the side jet channel 5 is ensured, the discharge capacity and the lifting pipe column speed are optimized according to the aperture of the side spray hole 20 (or the installed side spray nozzle) and the ground rated pump pressure, and circulation is carried out at the optimized discharge capacity, meanwhile, the drilling tool is lifted up to realize dynamic flushing, and similarly, the abrasive dust is swept from bottom to top by fluid, and the effect of reversely discharging the previous abrasive dust can be achieved once only by properly matching the discharge capacity, the lifting speed and the aperture of the side spray hole 20 (or the installed side spray nozzle);

and fourthly, repeating the second step and the third step until the bridge plug drilling and grinding is completed.

As shown in fig. 10, the optimized lateral jet flow velocity Vf is obtained by optimizing the aperture and the discharge capacity of the lateral spray hole 20 (or the installed lateral spray nozzle), and a larger annular fluid velocity Vf can be obtained by matching the optimized drill lifting velocity Vp.

The third step numerical value N can be determined by the maximum discharge capacity of the surface pump, the maximum lifting speed of the pipe column, the drilling and grinding speed, the driller experience and the like, and is corrected by comparing the theoretical chip removal amount with the actual chip removal amount collected at the well mouth, so that the better drilling and grinding efficiency is ensured.

The bit pressure control type downhole circulation short circuit can be used for similar downhole construction except for a drilling and grinding bridge plug process of a coiled tubing, and is within the protection range of the application.

With reference to the drilling pressure control type underground circulation short circuit and continuous pipe drilling plug dynamic flushing process shown in the figures 1 to 10, the following physical simulation experiment is carried out, and the specific parameters are 50.8mm continuous pipe, 90mm well hole size and 7870Kg/m bridge plug abrasive dust density³The mixed large-size bridge plug abrasive dust with the bridge plug abrasive dust sizes of 16 mm, 20 mm and 40mm has the well inclination angle of 90 degrees, the fluid is water, and the discharge capacity range is 12.0-27.2m³And h, two lateral nozzles are uniformly distributed on the joint upper section 21:

scheme 1: the upper section 21 of the connector is provided with 6 side spray holes 20, a phi 15.51mm lateral spray nozzle A is arranged in each side spray hole 20, and the sum of the cross sections of all the side spray holes 20 is 11.33cm²Slightly smaller than the sum of the cross-sectional areas of the overflowing holes 12;

scheme 2: the upper section 21 of the connector is provided with 8 side spray holes 20, a phi 9.525mm lateral spray nozzle B is arranged in each side spray hole 20, and the sum of the sectional areas of all the side spray holes 20 is 5.7cm²And is smaller than the sum of the sectional areas of the side nozzles A in the scheme 1.

Experimental results as shown in fig. 8 and 9, from the experimental results, the circulation short circuit of the present invention can greatly increase the upward return speed of the bridge plug swarf, and the larger the jet flow speed (the more the discharge capacity is consistent, the smaller the sum of the nozzle hole diameter cross-sectional areas is, the larger the jet flow speed is), the higher the upward return speed of the swarf is.

Certainly, when the annular reverse discharge speed is increased through the side jet holes 20, two situations that the main flow channel 10 is closed or opened can exist, firstly, the main flow channel 10 is kept unchanged, and only part of fluid is flushed out from the side jet holes 20; secondly, the main flow channel 10 is closed, and all the fluid is flushed out from the side spray holes 20, namely, the scheme provided by the invention has higher design difficulty, but theoretical calculation and indoor experiments show that the jet speed of the scheme is greatly improved, the flushing effect is obviously better than that of the scheme for opening the main flow channel 10, and under the same condition of the 8 phi 9.525mm side spray nozzles B, when the side spray nozzles work, the jet speed comparison results are as follows under two conditions of opening and closing the main flow channel 10:

from this, under the condition that sprue 10 was opened, the side direction efflux was used lessly, and promotion to the chip removal effect is limited, and when adopting the structure of this application, its efflux speed promoted about 3 times, and the chip removal effect obviously strengthens, if further optimization such as efflux aperture, angle, the chip removal effect will further promote.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.