CN112593893A - Multipurpose single-stage continuous well cementation method for preventing pollution of production zone - Google Patents

Abstract

The invention provides a multipurpose single-stage continuous well cementation method for preventing a production zone from being polluted, which belongs to the technical field of coal bed gas well cementing.

Description

Multipurpose single-stage continuous well cementation method for preventing pollution of production zone

Technical Field

The invention belongs to the technical field of coal bed gas well cementing, and particularly discloses a multipurpose single-stage continuous well cementing method capable of preventing a production zone from being polluted.

Background

At present, in a conventional coal bed gas pre-pumping vertical well, for the purposes of preventing collapse of a well wall and isolating a water-bearing stratum, a full-well-section cement well cementation method is generally adopted, solid-phase particles and filtrate in cement slurry easily enter pores of a coal reservoir stratum during well cementation, and a part of coal bed gas migration channels are blocked, so that the coal reservoir stratum is damaged. In order to reduce the damage to the coal reservoir in the well cementation process, the process methods of low-density cement slurry well cementation, graded well cementation, plug flow displacement well cementation and the like are mainly adopted, although the damage of the cement slurry to the coal reservoir is relieved to a certain extent, the current situation that the cement slurry contacts and invades the coal reservoir cannot be avoided fundamentally, and finally the damage to the coal reservoir in different degrees is caused.

CN101975041A discloses a method and a device for cementing wells around coal seams, which can realize continuous full-well cementing and can be applied to multi-producing zone combined discharge and mining. Although the device can make the coal seam not contact with well cementation cement paste, the damage of the well cementation cement paste to the coal seam is avoided. However, the well cementing device is directly connected with the production casing, and the structure in the well cementing device is complex, so that after the well cementing is completed, the difficulty of the discharging and extracting equipment to enter the production casing is high, the discharging and extracting in the later period are affected, and the complex well cementing device increases the well cementing cost and is not beneficial to the practical field application.

When the coal-bed gas well passes through the goaf, the coal-bed gas well is damaged or destroyed due to the residual deformation of the old goaf and the disturbance of the new mining area. The patent CN107313745A discloses a well cementation method for reinforcing a coal-bed gas well by multi-node intensive grouting in an over-goaf, and CN107313716A discloses a well drilling method for penetrating the coal-bed gas well with a hole bottom blocking a broken rock mass through the goaf.

Disclosure of Invention

In view of the defects of the well cementation process of combined drainage and production wells of various production layers, the invention provides a multi-purpose single-stage continuous well cementation method for preventing pollution to the production layers, the method is suitable for a vertical well and a horizontal well, and the well body structure of the vertical well is a two-opening well body structure; the well body structure of the horizontal well is a three-opening well body structure; the vertical well mainly comprises well cementation of a plurality of production layer combined drainage production wells, wherein well cementation of a goaf coal-bed gas well and well cementation of a goaf and the goaf, a goaf and coal reservoir, a multi-layer coal reservoir and a coal-based gas multi-layer production layer combined drainage production well are mainly used for sectional fracturing well cementation, and the purpose of preventing well cementation cement slurry from damaging the production layers is achieved.

In order to achieve the above object, the present invention provides a multi-purpose single-stage continuous well cementing method for preventing pollution to a producing zone, comprising the steps of:

s1, adopting an underbalanced drilling process to drill a well to a preset distance below a bottom plate of the target coal seam section, stopping drilling, lifting a drilling tool, and determining the position and the thickness of a target production layer;

s2, mounting a sleeve outside the production sleeve according to the position and the thickness of a target production zone, wherein the sleeve comprises an upper annular rubber sleeve, a lower annular rubber sleeve and a cement slurry channel penetrating through the upper annular rubber sleeve and the lower annular rubber sleeve, the annular rubber sleeve comprises a water-permeable rubber sleeve and a water-absorbing expansion material filled in the water-permeable rubber sleeve, a float collar and a float shoe are mounted at the bottom end of the production sleeve, and the production sleeve is put into the well shaft so that the upper annular rubber sleeve and the lower annular rubber sleeve are respectively positioned at a preset distance above a top plate of the target production zone and at a preset distance below a bottom plate;

s3, injecting water from the production casing and the annulus between the production casing and the well wall to expand the annular rubber cylinder to block the annulus between the production casing and the well wall and isolate a target production layer;

s4, pouring isolation liquid, cementing, opening a stop pin and a rubber plug, replacing slurry, performing impact pressing, cementing and waiting for setting.

Furthermore, the cement slurry channel is a circular pipe, a plurality of circular pipes are uniformly welded outside the production casing pipe, and the upper annular rubber cylinder and the lower annular rubber cylinder are bonded on the circular pipe and the production casing pipe through the bonding agent.

Furthermore, the cement slurry channel is a fan-shaped ring pipe, a plurality of fan-shaped ring pipes are uniformly arranged along the outer wall of the production casing pipe, a supporting framework is arranged between every two adjacent fan-shaped ring pipes, the inner walls of the fan-shaped ring pipes and the supporting framework are welded outside the production casing pipe, and an upper annular rubber cylinder and a lower annular rubber cylinder are bonded on the outer walls of the fan-shaped ring pipes and the supporting framework through bonding agents.

Further, in step S1, an underbalanced drilling process is used to drill a well to 30-50m below the floor of the target coal seam section.

Further, in step S2, the distance between the upper ring rubber cylinder and the top plate of the target zone and the distance between the lower ring rubber cylinder and the bottom plate of the target zone are both 0.5 m.

Furthermore, the highest pressure resistance of the upper ring-shaped rubber cylinder and the lower ring-shaped rubber cylinder after water absorption and expansion is 60 MPa.

Further, in step S3, the water injection amount is higher than the top plate of the uppermost-purpose producing zone.

Further, in step S4, a fluid loss additive and a stabilizer are added to the cement slurry before the cement is injected, and the distance between the cement return height and the top plate of the uppermost target producing zone is 150m or less.

Further, the single-stage continuous well cementation method also comprises the following steps,

and S5, logging again after well cementation and waiting coagulation, detecting the well cementation quality, and completing the well cementation operation after the design requirements are met.

The invention has the following advantages:

by adopting the multi-purpose single-stage continuous well cementation method for preventing pollution of the production layer, cement slurry enters the annular area of the top bottom plate of the target production layer through the cement slurry channel, so that the cement slurry is prevented from entering the annular area of the target production layer, the damage to the production layer caused by solid-phase particles and filtrate in the cement slurry entering the hole cracks of the production layer is effectively reduced, and the purposes of high yield and stable yield of a gas well can be realized. Moving parts such as mechanical or hydraulic packers and the like are not adopted, so that the whole set of well cementation device is simple, safe, reliable and relatively low in cost. The highest pressure resistance of the upper annular rubber cylinder and the lower annular rubber cylinder after water absorption and expansion can reach 60Mpa, which is far higher than the highest pump pressure value in the conventional well cementation process.

Drawings

FIG. 1 is a schematic view of a well bore structure according to example 2;

FIG. 2 is a first structural view of the cuff;

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a second structural view of the cuff;

FIG. 5 is a top view of FIG. 4;

FIG. 6 is a schematic illustration of a spacer fluid;

FIG. 7 is a schematic illustration of cementing;

FIG. 8 is a schematic view of the trip pin, ejecting the plug;

FIG. 9 is a schematic view of a slurry replacement slurry;

FIG. 10 is a schematic view of the bump;

FIG. 11 is a schematic view of the well bore structure of example 6.

In the figure: 1-producing a casing; 2-oversleeves; 2.1-upper ring rubber cylinder; 2.2-lower ring rubber cylinder; 2.3-grout passage; 2.4-supporting the skeleton; 3-floating hoop; 4-floating shoes; 5-surface casing pipe; 6-opening a shaft; 7-first-opening well cement; 8-technical sleeve; 9-opening a shaft for two times; 10-second-opening well cementing cement; 11-three-opening the shaft; 12-three-opening well cementation cement; 13-a goaf; 14-target zone I; 15-destination zone II; 16-pressure gauge; 17-a rubber plug; 18-a pin; 19-drilling fluid; 20-an insulating fluid inlet; 21-spacer fluid; 22-a cementing cement inlet; 23-cementing cement; 24-displacing liquid; 25-pushing a rubber plug; 26-displacement fluid inlet; 27-coal seam.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment provides a multipurpose single-stage continuous well cementation method for preventing pollution of a production zone, which comprises the following steps:

s1, according to basic information such as contour lines of a coal seam floor, adopting an underbalanced drilling process to drill a well to a preset distance below the floor of a target coal seam section, stopping drilling, extracting a drilling tool, and accurately determining the position and the thickness of a target production layer by using a logging means;

s2, installing a sleeve 2 outside a production casing 1 according to the position and the thickness of a target production zone, wherein the sleeve 2 comprises an upper annular rubber sleeve 2.1, a lower annular rubber sleeve 2.2 and a cement slurry channel 2.3 penetrating through the upper annular rubber sleeve 2.1 and the lower annular rubber sleeve 2.2, the annular rubber sleeve comprises a water-permeable rubber sleeve and a water-absorbing expansion material filled in the water-permeable rubber sleeve, a float collar 3 and a float shoe 4 are installed at the bottom end of the production casing 1, and the production casing 1 is put into a shaft, so that the upper annular rubber sleeve 2.1 and the lower annular rubber sleeve 2.2 are respectively positioned at a preset distance above a top plate of the target production zone and at a preset distance below a bottom plate;

s3, injecting water from the production casing 1 and the annulus between the production casing 1 and the well wall, so that the annular rubber cylinder expands to block the annulus between the production casing 1 and the well wall, and isolating a target production layer;

s4, pouring spacer fluid, cementing, opening a stop pin and a rubber plug, replacing slurry, performing collision pressure, cementing and setting-waiting;

and S5, logging again after well cementation and waiting coagulation, detecting the well cementation quality, and completing the well cementation operation after the design requirements are met.

Further, the cement slurry channel 2.3 is a circular pipe, a plurality of circular pipes are uniformly welded outside the production casing 1, and the upper annular rubber cylinder 2.1 and the lower annular rubber cylinder 2.2 are bonded on the circular pipe and the production casing 1 through a bonding agent; the cement slurry channel 2.3 is a whole section of complete casing, namely, connecting pieces such as casing couplings and the like do not exist, and parameters such as caliber, pipeline friction and the like can meet the basic requirement of effective passing of the well cementation cement slurry.

Further, grout passageway 2.3 is the ring canal of fan, and a plurality of ring canals of fan evenly arrange along production casing 1's outer wall, for supporting framework 2.4 between two adjacent ring canals of fan, and the inner wall of the ring canal of fan and supporting framework 2.4 all welds outside production casing 1, encloses into the synthetic ring shape, goes up annular packing element 2.1 and lower annular packing element 2.2 and bonds on the outer wall of ring canal of fan and supporting framework 2.4 through the binder.

Further, in step S1, an underbalanced drilling process is used to drill a well to 30-50m below the floor of the target coal seam section.

Further, in step S2, the distance between the upper ring rubber sleeve 2.1 and the top plate of the target zone and the distance between the lower ring rubber sleeve 2.2 and the bottom plate of the target zone are both 0.5 m.

Further, the highest pressure resistance after the upper ring rubber cylinder 2.1 and the lower ring rubber cylinder 2.2 absorb water and expand is 60 MPa.

Furthermore, in step S3, the water injection amount is higher than the top plate of the uppermost layer of the target production zone, so as to ensure that the expansion progress of the annular rubber cylinders is consistent, and achieve the purpose of synchronously separating the top plate and the bottom plate of the target production zone.

Further, in step S4, when cement slurry fills the annular area at the lower part of the annular rubber cylinder of the bottom plate of the target production zone and then rises into the annular area of the top plate through the cement slurry channel, the pump pressure will rise obviously, and before the cement slurry is injected, a fluid loss agent and a stabilizer are added into the cement slurry, so as to control the distance between the cement height return and the top plate of the target production zone at the uppermost layer within 150m, thereby avoiding adverse effects caused by high pump pressure as much as possible.

Example 2

In this embodiment, the single-stage continuous well cementation method described in embodiment 1 is specifically described by taking the well cementation of the coal-bed gas well in the goaf as an example, as shown in fig. 2, the target production zone i 14 and the target production zone ii 15 are both coal reservoirs, and the goaf-passing well is a coal-bed gas well which passes through the goaf and pre-pumps lower group coal, and the implementation steps are as follows.

1) The well body structure of the cross goaf well adopts a two-well-body structure: drilling a hole with the diameter of 311mm to 10m below bedrock, putting a 244.5mm surface casing 5, and cementing and returning to the hole opening; the diameter of the second opening is 215.9mm, the drilling is finished until the diameter is 30m below a target coal seam, and the specification of the production casing 1 is 139.7 mm.

2) The sleeve 2 is arranged on a target production layer, the position of the annular rubber cylinder is 0.5m above a top plate of the target production layer and 0.5m below a bottom plate of the target production layer, the position of the outer surface of the production sleeve 1 is the position, from top to bottom, of the well cementation tool string: well head cementing device, production casing 1, oversleeve 2, float collar 3, float shoe 4.

3) After the well cementation tool string is installed, firstly, injecting a proper amount of clear water into the annular space of the production casing 1, the production casing 1 and the well wall to ensure that the annular rubber cylinder expands to a production layer capable of effectively isolating a target, and then performing well cementation operation by adopting conventional well cementation methods such as isolation liquid injection, rubber plug feeding, replacement of slurry, impact pressing and the like;

4) and logging again after well cementation and waiting for setting, detecting the well cementation quality, and completing the well cementation operation after the design requirements are met.

5) And perforating, fracturing, and discharging and extracting, wherein perforating and fracturing are only needed to be carried out on the lower coal reservoir group.

Example 3

The single-stage continuous well cementation method in the embodiment 1 is adopted in well cementation of combined mining gas wells of a goaf and a lower coal reservoir, wherein a target production layer I14 and a target production layer II 15 are coal reservoir layers, the well body structure and the well cementation method are the same as those in the embodiment 2, after well cementation and completion, after perforation and fracturing of the lower coal reservoir layer are completed, perforation is carried out on a target interval of the goaf, and then combined drainage and mining are carried out on multiple production layers.

Example 4

Example 3 is the same as the combined drainage and mining of multi-layer coal reservoirs and multi-layer coal-series gas.

Example 5

And (3) performing combined drainage and mining in the multilayer goaf, perforating the target goaf section after the well cementation is finished, and performing negative pressure drainage on the ground after the drainage and mining equipment is installed.

Example 6

The single-stage continuous well cementation method of the embodiment 1 is adopted in the coal bed gas horizontal well, and the implementation steps are as follows.

The horizontal coal-bed gas well adopts a three-opening well body structure, wherein the opening diameter is 425mm, the horizontal coal-bed gas well is drilled to 10m below bedrock, a 377mm surface casing 5 is put in, and well cementation is returned to an orifice; drilling a secondary opening with the aperture of 311mm to a landing point of a target coal seam, putting a 244.5mm technical casing 8, and cementing and returning to the ground; three openings with the aperture of 215.9mm are drilled to a target point, a production casing 1 with the diameter of 139.7mm is put in, sleeves 2 are installed at a target layer section, and the position of the annular rubber cylinder is 0.5m above a top plate of the target production layer and 0.5m below a bottom plate of the outer surface of the production casing 1; the bottom of the production casing 1 is provided with a float collar 3 and a float shoe 4 for well cementation. The process flow of the well cementation is the same as that of the embodiment 2, after the well cementation is finished, fracturing and perforating are carried out on the target interval, and drainage and production equipment is installed for drainage and production.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (9)

1. A multi-purpose single-stage continuous well cementation method for preventing pollution to a production zone is characterized by comprising the following steps:

s1, adopting an underbalanced drilling process to drill a well to a preset distance below a bottom plate of the target coal seam section, stopping drilling, lifting a drilling tool, and determining the position and the thickness of a target production layer;

s2, mounting a sleeve outside the production sleeve according to the position and the thickness of a target production zone, wherein the sleeve comprises an upper annular rubber sleeve, a lower annular rubber sleeve and a cement slurry channel penetrating through the upper annular rubber sleeve and the lower annular rubber sleeve, the annular rubber sleeve comprises a water-permeable rubber sleeve and a water-absorbing expansion material filled in the water-permeable rubber sleeve, a float collar and a float shoe are mounted at the bottom end of the production sleeve, and the production sleeve is put into the well shaft so that the upper annular rubber sleeve and the lower annular rubber sleeve are respectively positioned at a preset distance above a top plate of the target production zone and at a preset distance below a bottom plate;

s3, injecting water from the production casing and the annulus between the production casing and the well wall to expand the annular rubber cylinder to block the annulus between the production casing and the well wall and isolate a target production layer;

s4, pouring isolation liquid, cementing, opening a stop pin and a rubber plug, replacing slurry, performing impact pressing, cementing and waiting for setting.

2. The multi-purpose, single-stage continuous well cementation method of preventing pollution to a production zone as claimed in claim 1, wherein the cement slurry channel is a circular tube, a plurality of circular tubes are uniformly welded outside the production casing, and the upper annular rubber tube and the lower annular rubber tube are bonded to the circular tube and the production casing by an adhesive.

3. The multipurpose single-stage continuous well cementation method for preventing pollution of a production zone as claimed in claim 1, wherein the cement slurry channel is a fan-shaped ring pipe, a plurality of fan-shaped ring pipes are uniformly arranged along the outer wall of the production casing, a support framework is arranged between two adjacent fan-shaped ring pipes, the inner walls of the fan-shaped ring pipes and the support framework are welded outside the production casing, and the upper annular rubber sleeve and the lower annular rubber sleeve are bonded on the outer walls of the fan-shaped ring pipes and the support framework through bonding agents.

4. The multi-purpose, single stage continuous well cementing method to prevent contaminated producing zones according to claim 1, wherein in step S1, the well is drilled to 30-50m below the floor of the target coal seam section using an underbalanced drilling process.

5. The multi-purpose, single-stage continuous well cementing method for preventing contamination of a producing zone according to claim 1, wherein the distance between the upper ring rubber cylinder and the top plate of the objective producing zone and the distance between the lower ring rubber cylinder and the bottom plate of the objective producing zone are both 0.5m in step S2.

6. The multi-purpose, single-stage continuous well cementation method of preventing contamination of a producing zone as claimed in claim 1, wherein the maximum pressure resistance after water absorption and expansion of the upper and lower ring packing cylinders is 60 Mpa.

7. The multi-purpose, contamination-free pay zone single stage continuous cementing method of claim 1, wherein in step S3, the water injection rate is higher than the top deck of the uppermost destination pay zone.

8. The multi-purpose, single-stage continuous well cementing method for preventing contamination of a producing zone according to claim 1, wherein a fluid loss additive and a stabilizer are added to the cement slurry before the cement is injected, and the distance between the cement back height and the top plate of the uppermost target producing zone is within 150 m.

9. The multi-purpose, single stage continuous cementing process to prevent contamination of a producing formation according to claim 1, further comprising,

and S5, logging again after well cementation and waiting coagulation, detecting the well cementation quality, and completing the well cementation operation after the design requirements are met.

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