1. A process method suitable for drilling a soluble bridge plug in a shale gas well is characterized by comprising the following steps: the method comprises the following steps:

s0 improved design of the structure of the grind shoe:

s01 grinding shoe integral breaking line type structure design: the grinding shoe comprises a drill bit, the diameter of the front end of the drill bit is smaller than that of the rear end of the drill bit, and the front end of the drill bit is in arc transition to the rear end of the drill bit;

s04 design of hydraulic chip removal structure of grind shoe: the front end of the drill bit is provided with a plurality of water holes, the radiuses of the positions of the water holes are different, the drill bit is provided with a chip groove, the chip groove extends from the front end of the drill bit to the rear end of the drill bit, the width of the chip groove is gradually widened from the front end of the drill bit to the rear end of the drill bit, and the width of the top of the chip groove is larger than the width of the bottom of the chip groove;

s1 air tap selection: reasonably adjusting the size of an air nozzle to enable the discharge capacity of an outlet to be larger than the discharge capacity of an inlet pump, observing the condition of back-discharge sand, and controlling the flame height of the outlet to be not more than 3 m; if the sand content of the back-draining sand circulation well-flushing is not reduced, the circulation is maintained, and the size of the air nozzle is properly adjusted until the sand content of the outlet is lower than 5 percent;

s2 weight on bit control: controlling the bit pressure in the drilling and grinding process, slowly applying the bit pressure to the bridge plug, keeping the bit pressure at 5-15 kN, and carrying out optimization adjustment in time;

s3 short start control: drilling with the tool string, removing 5-8 drilling cuttings or drilling cuttings returning according to drilling and grinding parametersThe number of short rise times is properly reduced, and 3-5m of pump injection liquid is injected after each 5 or more bridge plugs are drilled³(ii) a After the scraps are cleaned, the scraps are pumped to a well deviation position of 30 degrees at a speed of less than or equal to 15m/min, and 10m is pumped³The glue solution is circularly washed for more than one week until the quality of the inlet and outlet liquid is the same.

2. The process for drilling a dissolvable bridge plug for a shale gas well according to claim 1, wherein said arc transition in S01 is a bit side, said bit side forming an outer cone, said outer cone having an outer cone angle of 6-8 degrees.

3. The process for drilling a soluble bridge plug for a shale gas well according to claim 2, wherein the drill bit front end is inclined from the drill bit side to the drill bit center to the drill bit rear end to form an inner cone having an inner cone angle of 86-88 degrees in S01.

4. The process for drilling a dissolvable bridge plug for a shale gas well according to claim 3, wherein said junction line of the bit front end and the bit side in S01 is a nose of the bit where the junction line of the bit front end and the bit side is rounded.

5. The process for drilling a dissolvable bridge plug for a shale gas well according to claim 4, wherein said S01 and S04 include S02 shoe milling cutting configuration design therebetween: the drill bit is provided with a cutting structure, the cutting structure comprises a main cutter body and an auxiliary cutter body which are fixedly connected to the drill bit, the main cutter body comprises two half main blades, the auxiliary cutter body comprises three auxiliary blades, the two half main blades and the three auxiliary blades are arranged on the drill bit from the inner cone to the outer cone, the end parts of the two half main blades in the inner cone of the drill bit are fixedly connected with each other, the three auxiliary blades are circumferentially and uniformly distributed around the two half main blades, and a plurality of cutting teeth are uniformly distributed on the two half main blades and the three auxiliary blades.

6. The process for drilling a soluble bridge plug for a shale gas well according to claim 5, wherein the cutting teeth are arranged in such a way that the distance between the inner teeth is 3-5mm, the distance between the middle teeth in the nose is 3-4mm, and the distance between the small teeth of the outer cone is 2.5-2.8 mm; in order to ensure uniform transition of the nose part and the outer cone, 8mmPDC (polycrystalline diamond compact) composite sheets are preferably selected as the cutting teeth, and a medium back inclination angle of 20 degrees is adopted.

7. The process for drilling a dissolvable bridge plug for a shale gas well according to claim 6, further comprising, between S02 and S04, a S03 wear shoe damage prevention casing structural design: the two half main blades and the three auxiliary blades extend to the rear end of the drill bit to form a random diameter section and a gauge section in sequence, the random diameter section comprises five non-gauge blades, the heights of the five non-gauge blades are increased in sequence, the gauge section comprises five gauge blades, and a plurality of active gauge teeth are embedded in the gauge blades.

8. The process method for drilling the soluble bridge plug for the shale gas well as claimed in claim 7, wherein in the step S3, a pump is injected with 3-5m of glue solution³And replacing the lower debris catcher with the upper and lower pressure difference of more than 2MPa to clean the debris.

9. The process for drilling a soluble bridge plug for shale gas wells as claimed in claim 8, wherein the step S3 is followed by a step S4 of performing a debris flowback clean: if the drill plug has negative pressure, the effect of back-flowing fragments is poor, or the number of the bridge plugs exceeds 15, 1-time midway cleaning can be added, namely, the drill plug tool string is lifted to a vertical well section by the midway cleaning, and the well is washed by clean water, large-displacement and positive circulation to clean the fragments or sand in the well shaft.

10. The process for drilling a soluble bridge plug for a shale gas well as claimed in claim 9, further comprising S5 flowback monitoring after said S4: the tool string is lowered to a well depth position with a well inclination of 30 degrees, the discharge capacity of an outlet is measured after a shaft volume is circulated at a fixed point by the discharge capacity of 400L/min, and the discharge capacity of the outlet is ensured to be larger than 300L/min by adjusting an air nozzle;

arranging a specially-assigned person to continuously monitor, taking a water sample every 30min, standing for 5min, suspending drilling and grinding when the sand setting proportion reaches more than 5%, lifting the tool string to leave the plug surface, alternately pumping circulating slick water and a KCl solution to clean the shaft until the outlet is normal and the sand content is less than 5%, and continuously lowering the drilling and grinding.

Background

As the shale gas field enters a development and adjustment period (the encrypted well is deployed on the plane, and the shale gas well at the upper or middle layer is deployed longitudinally), the pore pressure is reduced and even negative pressure is generated as the shale gas around the old well is continuously extracted. The use of soluble bridge plugs in infill and upper gas-bed wells is promoted. And (4) gradually optimizing and adjusting the running depth of the soluble bridge plug according to the well track. The conventional flat bottom mill shoe or PDC mill shoe is cylindrical in shape, and during drilling, the diameter of the front end of a drill bit needs to be manufactured to be in accordance with the actual size of a drilled bridge plug, so that the stress area of the front end of the drill bit is large, the required power is increased, the resistance is also large, and the mill shoe is easy to wear; on the other hand, the water holes are uniformly distributed at the front end of the grinding shoe, so that water is not easy to concentrate when chips are removed by impact, large fragments are difficult to return and too many, the grinding shoe is easy to block a drill, and the drilling through rate is reduced; on the other hand, in the process of drilling the soluble bridge plug, the conventional process that 5 soluble bridge plugs need to be drilled for short-lift operation, glue is filled before short-lift operation for chip cleaning, then drilling is continued, and the problem that cleaning is not clean easily occurs, so that drilling difficulty is caused.

Disclosure of Invention

The invention aims to provide a process method suitable for drilling a soluble bridge plug in a shale gas well, and aims to solve the problems that the front end of a drill bit is large in stress area, large in resistance and easy to wear a grinding shoe, large fragments are not easy to flowback and easily block a drill, and drilling is difficult due to the fact that the fragments are not cleaned completely in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

a process method suitable for drilling a soluble bridge plug in a shale gas well comprises the following steps:

s0 improved design of the structure of the grind shoe:

s01 grinding shoe integral breaking line type structure design: the grinding shoe comprises a drill bit, the diameter of the front end of the drill bit is smaller than that of the rear end of the drill bit, and the front end of the drill bit is in arc transition to the rear end of the drill bit;

s04 design of hydraulic chip removal structure of grind shoe: the front end of the drill bit is provided with a plurality of water holes, the radiuses of the positions of the water holes are different, the drill bit is provided with a chip groove, the chip groove extends from the front end of the drill bit to the rear end of the drill bit, the width of the chip groove is gradually widened from the front end of the drill bit to the rear end of the drill bit, and the width of the top of the chip groove is larger than the width of the bottom of the chip groove;

s1 air tap selection: reasonably adjusting the size of an air nozzle to enable the discharge capacity of an outlet to be larger than the discharge capacity of an inlet pump, observing the condition of back-discharge sand, and controlling the flame height of the outlet to be not more than 3 m; if the sand content of the back-draining sand circulation well-flushing is not reduced, the circulation is maintained, and the size of the air nozzle is properly adjusted until the sand content of the outlet is lower than 5 percent;

s2 weight on bit control: controlling the bit pressure in the drilling and grinding process, slowly applying the bit pressure to the bridge plug, keeping the bit pressure at 5-15 kN, and carrying out optimization adjustment in time;

s3 short start control: drilling is carried out by a tool string, 5-8 drilling tools are removed, or the number of short-rise times is properly reduced according to drilling and grinding parameters and chip return conditions, 5 or more bridge plugs are drilled each time,3-5m of pump injection liquid³(ii) a After the scraps are cleaned, the scraps are pumped to a well deviation position of 30 degrees at a speed of less than or equal to 15m/min, and 10m is pumped³The glue solution is circularly washed for more than one week until the quality of the inlet and outlet liquid is the same.

The technical principle and the beneficial effects of the invention are as follows:

1. the front end of the drill bit contacts the bridge plug first, the diameter of the front end of the drill bit is smaller than that of the rear end of the drill bit, and the rear end of the drill bit is the actual size of the bridge plug, so that the front end of the drill bit is smaller than the actual size of the bridge plug, during drilling, the drill bit gradually moves to the rear end of the drill bit from the front end of the drill bit, and gradually drills the bridge plug in a hole expanding manner, so that the contact area between the front end of the drill bit and the bridge plug is reduced, the stress area is reduced, the abrasion of the front end of the drill bit is reduced, the periphery of the drill bit is more uniformly stressed due to the gradual hole expanding, the stress of a certain part of the drill bit.

2. Improve a plurality of water holes design position for position radius diverse, a plurality of water holes are changeed and are concentrated liquid, change impact and parcel bold piece, combine the design of chip groove three-dimensional trapezium structure, the chip groove bottom is easily discharged little piece, the chip groove top is easily discharged big piece, when big piece is discharged, the bottom constantly has liquid and little piece supplementary, thereby change with the piece discharge, difficult stifled well and the sticking of a tool, the drilling through rate obtains improving betterly.

3. The pump glue injection liquid can tentatively clear away the piece before the short plays, and the back of playing for a short time, annotates a larger amount of glue liquid at the pump and has carried out the secondary and clear up the piece, and a larger amount of glue liquid need circulate well-flushing a week moreover to make the piece clear away more thoroughly, clean, thereby make to creep into more easily.

Further, in the step S01, the arc transition is the side part of the drill bit, the side part of the drill bit forms an outer cone, and the outer cone has an outer cone angle of 6-8 degrees.

Has the advantages that: the drill bit is enabled to form an ultra-long outer cone structure, the tooth distribution density can be effectively improved due to the design of the ultra-long outer cone, the wear resistance of the outer cone is guaranteed, and meanwhile, the drilling and grinding stability can be improved due to the ultra-long outer cone.

Further, the front end of the bit is inclined from the side of the bit to the center of the bit toward the rear end of the bit to form an inner cone having an inner cone angle of 86 to 88 degrees in S01.

Has the advantages that: the adoption of 86-88 degree ultra-shallow inner cone angle can shorten the inner cone length on the basis of ensuring chip removal, reduce the tooth distribution density, further reduce the contact area and effectively improve the drilling machine speed, when drilling the plug, the shallow inner cone makes the side part of the drill bit contact the bridge plug firstly, then the bridge plug contacts the center of the drill bit gradually from the side part of the drill bit, the drilling abrasion is more moderate, the bottom hole modeling can be better carried out, the bottom hole shape is matched with the contact surface of the drill bit, thereby reducing the vibration of the drill bit, reducing the impact force during drilling and reducing the contact probability with the casing.

Further, in S01, the connecting line between the front end of the drill bit and the side portion of the drill bit is the nose portion of the drill bit, and the connecting line between the front end of the drill bit and the side portion of the drill bit is rounded at the nose portion.

Has the advantages that: by adopting the profile of the one-section type arc nose part, the high tooth distribution density and the good stress condition of the nose part can be ensured, and the drill is not easy to wear when meeting a metal slip.

Further, the design of the shoe grinding structure between S01 and S04 comprises S02: the drill bit is provided with a cutting structure, the cutting structure comprises a main cutter body and an auxiliary cutter body which are fixedly connected to the drill bit, the main cutter body comprises two half main blades, the auxiliary cutter body comprises three auxiliary blades, the two half main blades and the three auxiliary blades are arranged on the drill bit from the inner cone to the outer cone, the end parts of the two half main blades in the inner cone of the drill bit are fixedly connected with each other, the three auxiliary blades are circumferentially and uniformly distributed around the two half main blades, and a plurality of cutting teeth are uniformly distributed on the two half main blades and the three auxiliary blades.

Has the advantages that: in the drilling process of the main cutter body, the stress is the largest part of the whole drill bit, the stress is more concentrated, the main cutter body is fixedly connected through the two half main cutter wings, the main cutter body is better in stress and stronger in bearing capacity, so that the main cutter body is not easy to damage, when a drill meets a metal sheet, due to the arrangement of the fixed connecting position, part of the metal sheet can be prevented from going deep into the drill bit, and the probability of drill clamping is reduced; the arrangement of the main cutter body and the auxiliary cutter body also enables the distribution of the cutting teeth to be more uniform, the unbalanced force received by the front end of the drill bit is less than 1% in the drilling and grinding process, and the stability of drilling and grinding is further improved.

Furthermore, the cutting teeth are arranged in a mode that the distance between the large teeth on the inner cone is 3-5mm, the distance between the medium teeth on the nose is 3-4mm, and the distance between the small teeth on the outer cone is 2.5-2.8 mm; in order to ensure uniform transition of the nose part and the outer cone, 8mmPDC (polycrystalline diamond compact) composite sheets are preferably selected as the cutting teeth, and a medium back inclination angle of 20 degrees is adopted.

Has the advantages that: the wear resistance of the nose and the outer cone can be well ensured by the above tooth spacing; 8mmPDC composite sheets are selected as the cutting teeth, so that the transition uniformity of the nose part and the outer cone part is ensured.

Further, the structural design of the abrasion-proof sleeve of the S03 mill shoe is also included between S02 and S04: the two half main blades and the three auxiliary blades extend to the rear end of the drill bit to form a random diameter section and a gauge section in sequence, the random diameter section comprises five non-gauge blades, the heights of the five non-gauge blades are increased in sequence, the gauge section comprises five gauge blades, and a plurality of active gauge teeth are embedded in the gauge blades.

Has the advantages that: the gauge protection section is used for protecting the gauge of the mill shoe, so that the mill shoe has strong gauge protection capability and can prevent the sleeve from being damaged; the active gauge protection teeth are adopted, so that the active gauge protection teeth can bear larger stress and have stronger gauge protection capability; in order to ensure the gauge protection function of the grinding shoe, the technical scheme adopts the random diameter section, a plurality of cutting teeth discharged in the same adjacent circumference above the random diameter section are unevenly arranged, and the number of the plurality of cutting teeth in the same adjacent circumference above the random diameter section is reduced in sequence, so that the frequency of impacting the bridge plug wall is reduced step by step, and the damage probability of the sleeve is reduced.

Further, in S3, 3-5m of pump glue injection liquid is injected into the pump³And replacing the lower debris catcher with the upper and lower pressure difference of more than 2MPa to clean the debris.

Has the advantages that: the debris catcher can efficiently catch and remove debris, and compared with glue solution, the glue solution needs longer flowing time and the debris catcher has higher efficiency.

Further, S4 is included after S3 for debris return cleaning: if the drill plug has negative pressure, the effect of back-flowing fragments is poor, or the number of the bridge plugs exceeds 15, 1-time midway cleaning can be added, namely, the drill plug tool string is lifted to a vertical well section by the midway cleaning, and the well is washed by clean water, large-displacement and positive circulation to clean the fragments or sand in the well shaft.

Has the advantages that: the increase is cleared up midway, can prevent that the piece from piling up to further clearing up the remaining piece of gas well internal accumulation for it changes the footage to creep into.

Further, S5 flowback monitoring is also included after S4: the tool string is lowered to a well depth position with a well inclination of 30 degrees, the discharge capacity of an outlet is measured after a shaft volume is circulated at a fixed point by the discharge capacity of 400L/min, and the discharge capacity of the outlet is ensured to be larger than 300L/min by adjusting an air nozzle;

arranging a specially-assigned person to continuously monitor, taking a water sample every 30min, standing for 5min, suspending drilling and grinding when the sand setting proportion reaches more than 5%, lifting the tool string to leave the plug surface, alternately pumping circulating slick water and a KCl solution to clean the shaft until the outlet is normal and the sand content is less than 5%, and continuously lowering the drilling and grinding.

Has the advantages that: the sand setting in the well is cleared in time, the excessive sand is prevented, the resistance of the mill shoe is reduced, and the service life of the mill shoe is prolonged.

Drawings

FIG. 1 is a perspective view of a process for drilling a soluble bridge plug for a shale gas well, which requires the use of a mill shoe according to the present invention;

FIG. 2 is a top view of the front end of a drill bit requiring a mill shoe for use in a process for drilling a soluble bridge plug for a shale gas well in accordance with the present invention;

FIG. 3 is a broken line type diagram of a process for drilling a soluble bridge plug for a shale gas well, which requires the use of a grinding shoe, according to the present invention;

FIG. 4 is a diagram of a distribution of inner cone cutting teeth of a mill shoe required in a process for drilling a soluble bridge plug for a shale gas well according to the present invention;

FIG. 5 is a diagram showing the distribution of cutting teeth and active gauge teeth of a mill shoe required in a process for drilling a soluble bridge plug for a shale gas well according to the present invention;

FIG. 6 is a graph of downhole turbulence intensity for a process for drilling a dissolvable bridge plug for a shale gas well that requires the use of a mill shoe in accordance with the present invention;

FIG. 7 is a graph of downhole cross flow velocity for a process of drilling a dissolvable bridge plug for a shale gas well requiring the use of a mill shoe in accordance with the present invention;

fig. 8 is a flow chart of an upward return flow of a fluid flow requiring a mill shoe in a process for drilling a soluble bridge plug for a shale gas well according to the present invention.

Detailed Description

The following is further detailed by way of specific embodiments:

reference numerals in the drawings of the specification include: the drill bit comprises a drill bit 1, a semi-main cutter wing 2, a cutting tooth 3, an auxiliary cutter wing 4, a random diameter wing 5, a gauge protection wing 6, a driving gauge protection tooth 7, a boss 8, a nose portion 10, an inner cone angle 11, an outer cone angle 12, a chip groove 13, a No. 1 water hole 14, a No. 2 water hole 15, a No. 3 water hole 9, a No. 4 water hole 16 and a No. 5 water hole 17.

Example one

A process method suitable for drilling a soluble bridge plug in a shale gas well comprises the following steps:

s0 improved design of the structure of the grind shoe:

s01 grinding shoe integral breaking line type structure design: as shown in fig. 3, the mill shoe comprises a drill bit 1, the diameter of the front end of the drill bit 1 is smaller than that of the rear end of the drill bit 1, the front end of the drill bit 1 is in arc transition towards the rear end of the drill bit 1, the arc transition is the side part of the drill bit 1, the side part of the drill bit 1 forms an outer cone, the outer cone angle 12 of the outer cone is 6-8 degrees, the outer cone angle 12 is preferably 7 degrees, the front end of the drill bit 1 inclines from the side part of the drill bit 1 to the center of the drill bit 1 to form an inner cone, the inner cone angle 11 of the inner cone is 86-88 degrees, the inner cone angle 11 is preferably 87 degrees, and the arc chamfer of the connecting line between the front end of the drill bit 1 and the side part of the drill bit 1 is the nose part 10 of the drill bit 1;

s02 design of the milling shoe cutting structure: as shown in fig. 1-4, a cutting structure is arranged on a drill bit 1, the cutting structure comprises a main cutter body and an auxiliary cutter body which are fixedly connected to the drill bit 1, the main cutter body comprises two half main blades 2, the auxiliary cutter body comprises three auxiliary blades 4, the two half main blades 2 and the three auxiliary blades 4 are arranged on a part from an inner cone and a nose part 10 of the drill bit 1 to an outer cone, the end parts of the two half main blades 2 positioned in the inner cone of the drill bit 1 are fixedly connected with each other, the three auxiliary blades 4 are circumferentially and uniformly distributed around the two half main blades 2, and a plurality of cutting teeth 3 are uniformly distributed on the two half main blades 2 and the three auxiliary blades 4; the cutting teeth 3 are arranged at intervals, wherein the interval between the large teeth is 3-5mm in the inner cone, the interval between the medium teeth is 3-4mm in the nose part 10, and the interval between the small teeth of the outer cone is 2.5-2.8 mm; in order to ensure that the transition between the nose part 10 and the outer cone is uniform, 8mmPDC (polycrystalline diamond compact) composite sheets are preferably selected as the cutting teeth 3, and a medium back inclination angle is 20 degrees;

s03 structural design of the wear-resistant sleeve of the grind shoe: as shown in fig. 1, two half main blades 2 and three auxiliary blades 4 extend towards the rear end of a drill bit 1 to sequentially form a random diameter section and a gauge section, the random diameter section comprises five irregular diameter blades 5, the heights of the five irregular diameter blades 5 are sequentially increased, the gauge section comprises five gauge blades 6, a plurality of mounting holes are formed in the gauge blades 6, active gauge teeth 7 are embedded in the mounting holes, bosses 8 are fixedly connected to the gauge blades 6 on the left side of the mounting holes, and the active gauge teeth 7 are also embedded in the bosses 8;

the boss 8 is used for installing the active gauge teeth 7, the active gauge teeth 7 are embedded on the boss 8, the boss 8 prolongs the length of the installation hole, the fixed depth of the active gauge teeth 7 is prolonged, the active gauge teeth 7 are firmly fixed, and the boss 8 can compensate the width of the active gauge teeth 7, so that the width of the active gauge teeth 7 is larger, the effective drilling and grinding service life of the teeth is prolonged, the boss 8 can provide better support for the active gauge teeth 7 under the action of larger drilling and grinding reaction torque, and the active gauge teeth 7 are not easy to wear or throw away;

s04 design of hydraulic chip removal structure of grind shoe: as shown in fig. 6-8, the inner cone of the drill bit 1 is positioned between the semi-main wing 2 and the sub-wing 4, and between the sub-wing 4 and the sub-wing 4, water holes are formed, the radii of the positions of the water holes are different, a chip discharge groove 13 is further formed between the semi-main wing 2 and the sub-wing 4, and between the sub-wing 4 and the sub-wing 4, the chip discharge groove 13 extends to the rear end of the drill bit 1 through the non-gauge wing 5 and the gauge wing 6, the width of the chip discharge groove 13 gradually widens from the front end of the drill bit 1 to the rear end of the drill bit 1, and the top width of the chip discharge groove 13 is greater than the bottom width of the chip discharge groove 13;

as can be seen from the bottom-hole overflowing velocity diagram in fig. 7, the jet flow is more uniform at the bottom-hole center, which is convenient for the upward return of the rock debris; as can be seen from the flow upward-returning line in FIG. 8, the flow is smoothly returned upward in the junk slots, which is convenient for the large rock debris to return upward.

The nozzle design in the port is as follows:

s1 air tap selection: for non-low-pressure and non-leakage wells, the size of an air nozzle (gas well outlet) is reasonably adjusted, so that the discharge capacity of the outlet is slightly larger than that of an inlet pump, the condition of back-discharge sand discharge is observed, and the flame height of the outlet is controlled to be not more than 3 m; if the sand content of the back-discharge sand circulation well-flushing is not reduced, the circulation is maintained, and the size of the air nozzle is properly adjusted until the sand content of the outlet is lower than 5 percent;

s2 weight on bit control: controlling the bit pressure in the drilling and grinding process, slowly applying the bit pressure to the bridge plug, keeping the bit pressure at 5-15 kN, and carrying out optimization adjustment in time;

s3 short start control: drilling a well by a tool string, and performing short-lifting for 1 time to a position with a well inclination of more than 30 degrees for each 3 soluble bridge plugs drilled and removed in a low-pressure and leakage well; removing 5-8 drilling cuttings of a non-low-pressure and leakage well or properly reducing the short-rise times according to drilling and grinding parameters and cuttings return conditions, wherein 3-5m of pump injection liquid is used for pumping every 5 or more bridge plugs after drilling³(ii) a Or the pressure difference between the upstream and the downstream of the lower debris catcher exceeds 2MPa for debris cleaning, the cleaned debris is short-lifted to a 30-degree well deviation position at the speed of less than or equal to 15m/min, and 10m is pumped³The glue solution is circularly washed for more than one week until the quality of the inlet and outlet liquid is the same;

s4, debris return cleaning: if the drilling plug has negative pressure, the effect of back-flowing fragments is poor, or the number of the bridge plugs exceeds 15, 1-time midway cleaning can be added, namely, the drilling plug tool string is lifted to a vertical well section for midway cleaning, and the well is washed by clean water, large-displacement and positive circulation to clean the fragments or sand in the well shaft;

s5 flowback monitoring: the tool string is lowered to a well depth position with a well inclination of 30 degrees, the discharge capacity of an outlet is measured after a shaft volume is circulated at a fixed point by the discharge capacity of 400L/min, and the discharge capacity of the outlet is ensured to be larger than 300L/min by adjusting an air nozzle;

arranging a specially-assigned person to continuously monitor, taking a water sample every 30min, standing for 5min, pausing drilling and grinding when the sand setting amount ratio reaches more than 5% (or the air output of outlet liquid obviously changes), lifting the tool string to leave the plug surface, alternately pumping circulating slickwater (or foam liquid) and KCl solution (the concentration of KCL is more than or equal to 15% and more than or equal to 10%) to clean the shaft until the outlet is normal and the sand content is less than 5%, and then continuously lowering the drilling and grinding.

The foregoing is merely an example of the present invention and common general knowledge of known specific structures and features of the embodiments is not described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.