CN114965956B

CN114965956B - Multifunctional casing for fracturing, permeability-increasing and cooperative repairing test of low-permeability polluted soil

Info

Publication number: CN114965956B
Application number: CN202210562969.2A
Authority: CN
Inventors: 冯世进; 石福江; 张晓磊; 郑奇腾; 方金城; 张旭
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2022-05-23
Filing date: 2022-05-23
Publication date: 2023-04-11
Anticipated expiration: 2042-05-23
Also published as: CN114965956A

Abstract

The invention belongs to the technical field of contaminated soil remediation, and provides a multifunctional casing for a fracturing and permeability-increasing synergic remediation test of low-permeability contaminated soil, which comprises a casing in a well cementation zone and a casing in a medium transmission channel zone; the casing of the well cementation zone is provided with a casing annulus, so that the rapid coagulant can be injected into the casing from a coagulant input hole at the top end and then output through the perforation on the first outer casing; the sleeve of the medium transmission channel area is provided with an internal attached circular tube, and the internal attached circular tube is driven to rotate by rotating the rotating handle of the steel rod so as to control the opening and closing of the medium transmission channel; the invention designs an upper function subarea and a lower function subarea, realizes two functions of well cementation seepage prevention and free opening and closing of a medium transmission channel, fills the blank of a laboratory scale multifunctional sleeve in the field, and powerfully promotes the development process of a laboratory test instrument for fracturing, permeability-increasing and cooperative repair of low-permeability polluted soil.

Description

Multifunctional casing for fracturing, permeability-increasing and cooperative repairing test of low-permeability polluted soil

Technical Field

The invention relates to the technical field of contaminated soil remediation, in particular to a multifunctional casing for a fracturing and permeability-increasing synergistic remediation test of low-permeability contaminated soil.

Background

In recent years, the national sustainable development strategy demand of carbon peak carbon neutralization in the field of environmental geotechnics is actively developing the repair management and control of polluted sites, and the repair measures applied to the polluted sites are gradually changed from heterotopic repair with high cost, large site disturbance and large repair engineering quantity to in-situ repair with low cost, small disturbance and simple and convenient construction. However, the existing research shows that the in-situ remediation technology has the problems of long remediation period, incomplete or excessive remediation period and the like in engineering application, and particularly in low-permeability polluted sites, the rapid migration of remediation agents in the low-permeability polluted sites is seriously retarded by the compact structure and low porosity of the polluted soil, so that the remediation effect is poor. The fracturing and permeability increasing technology is considered to be an effective method for increasing the permeability of a low-permeability polluted site and improving the repairing effect in cooperation with other repairing methods, and can be roughly divided into a hydraulic fracturing technology and a pneumatic fracturing technology according to the difference of media used for expanding a primary fracture or increasing a new fracture. However, most of the existing fracturing and permeability-increasing collaborative repair results are from engineering practices, and corresponding indoor model test instruments are lacked to deeply probe the fracturing and repair development processes and reveal the fracture-making mechanism and the solute migration rule. One key to realizing the fracturing and permeability-increasing cooperative repair operation in the indoor model test instrument is to arrange a casing pipe in the polluted soil sample to provide a channel for injecting a fracturing and repairing medium into or extracting a multiphase medium from the polluted soil. The casing needs to fulfill two basic functions, one of which is fracturing cementing: the method has the advantages that the injection of fluid media is avoided to form a preferential seepage channel along the outer wall of the casing, cement grouting is adopted in engineering, the preferential seepage channel on the outer wall of the casing is filled and solidified preferentially after cement slurry is reversely discharged, but for indoor tests, the method has the defects of long cement slurry solidification time consumption, difficult casing cleaning, large environmental disturbance and the like; secondly, a medium transmission channel on the outer wall of the switch sleeve: the outer wall of the casing is kept closed during loading and consolidation, so that soil around the casing is prevented from being extruded into the casing, and a medium transmission channel needs to be opened to allow fluid media to be freely transmitted during fracturing infiltration or repairing operation. At present, a sleeve satisfying the above functions has not been developed yet. Therefore, the research and development of the multifunctional casing matched with the research and development process for promoting the research and development process of the indoor test instrument for fracturing, permeability-increasing and cooperative repair of low-permeability polluted soil are urgent.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a multifunctional casing for a fracturing and permeability-increasing synergic repair test of low-permeability polluted soil.

In order to achieve the above purpose, the solution of the invention is as follows:

a multifunctional casing for a fracturing, permeability-increasing and cooperative repairing test of low-permeability polluted soil, comprising: the well fixing area comprises a well fixing area sleeve (1) and a medium transmission channel area sleeve (2); the solid-well area sleeve (1) and the medium transmission channel area sleeve (2) are of an integral structure, the solid-well area sleeve (1) is located on the upper portion, and the medium transmission channel area sleeve (2) is located on the lower portion.

Wherein the cementing well casing (1) comprises: a first outer sleeve (108) and an inner sleeve (109); a gap is arranged between the first outer sleeve (108) and the inner sleeve (109) and is called a sleeve annulus (101); a plurality of rows of perforations (110) are arranged in the outer sleeve I (108) along the normal direction, each row of perforations (110) is positioned on the same cross section, and the perforations are uniformly distributed on the wall of the outer sleeve I (108); the perforations (110) of adjacent rows are staggered vertically, and the lower row of perforations are positioned on the central line of the connecting line of the adjacent perforations of the upper row; the inner sleeve (109) is not subjected to any hole opening treatment; the bottom end of the casing annular space (101) is rigidly connected and sealed by a first outer casing pipe (108) and an inner casing pipe (109), and the top end of the casing annular space (101) is completely open;

the medium transmission channel area sleeve (2) comprises a second outer sleeve (206), a medium transmission channel (205), an inner attached circular tube (201), a ball (203), a groove base (204) and a steel rod (102); a plurality of medium transmission channels (205) are arranged on the second outer sleeve (206) along the circumferential direction, and the medium transmission channels (205) penetrate through the pipe wall of the second outer sleeve (206); the inner attached circular tube (201) is arranged in the outer sleeve II (206), the outer wall of the inner attached circular tube is tightly attached to the inner wall of the outer sleeve II (206), and inner attached circular tube orifices (202) with the same shape, size and number as the medium transmission channel (205) are formed;

the bottom of the internal round tube (201) is provided with a downward groove; a groove base (204) is arranged on the inner wall of the second outer sleeve (206); a plurality of balls (203) which are closely arranged in a circle are arranged between the groove base (204) and the groove of the inner attached circular pipe (201); weld steel pole (102) on interior attaches pipe (201), the sleeve pipe top is extended along the sleeve pipe inboard to steel pole (102), steel pole (102) top level is buckled into steel pole turning handle (105), can make interior attaches pipe (201) rotate on the recess base (204) that cloth has ball (203) through rotatory steel pole turning handle (105), when medium transmission passageway (205) and interior attaches pipe drill way (202) coincidence, can realize the free transmission of medium, when medium transmission passageway (205) and interior attaches pipe drill way (202) stagger completely, can close the medium transmission passageway (205) of outer tube (108).

Using scenario 1, the casing annulus (101) may be embedded in a solid circular tube (111), the solid circular tube (111) being sized to match the casing annulus (101);

using the scene 2, the sleeve annulus (101) can be kept hollow and a T-shaped rubber plug (107) is embedded into the top end, and a right-angle fixed steel ring (104) is covered on the T-shaped rubber plug (107); a coagulant input hole (106) penetrates through the T-shaped rubber plug (107) and the right-angle fixed steel ring (104) and is communicated with the sleeve annulus (101) from the outside; and a plurality of fixing bolts (103) are inserted into the contact area of the right-angle fixing steel ring (104) and the first outer sleeve (108) along the periphery of the pipe, and the fixing bolts (103) penetrate through the right-angle fixing steel ring (104) and are embedded into the first outer sleeve (108) but do not penetrate through the first outer sleeve to ensure that the top end of the annular sleeve (101) is sealed.

Due to the adoption of the scheme, the invention has the beneficial effects that:

the multifunctional casing pipe fills the blank of the casing pipe required by the indoor test instrument for fracturing and permeability-increasing collaborative repair of low-permeability polluted soil, two major functions of well cementation and seepage prevention and free opening and closing of a medium transmission channel are respectively realized by the upper partition and the lower partition, various fracturing and permeability-increasing tests such as hydraulic fracturing, pneumatic fracturing and multi-stage combined fracturing and various in-situ repair tests such as in-situ chemical oxidation, in-situ multiphase extraction, in-situ thermal desorption and thermal enhanced gas phase extraction can be carried out in an indoor low-permeability polluted soil sample unit through the multifunctional casing pipe, and the development process of the indoor test instrument for fracturing and permeability-increasing collaborative repair of low-permeability polluted soil is forcefully promoted.

Drawings

Fig. 1 is a schematic longitudinal sectional view of the multifunctional casing according to the embodiment.

FIG. 2 is a schematic structural view of a solid circular tube capable of being inserted into a casing annulus of a multi-functional casing-in-well zone in the present embodiment.

Fig. 3 is a working principle diagram of the multifunctional bushing provided by the embodiment.

Reference numerals: a-longitudinal section of a sleeve, B-longitudinal section of an outer sleeve, 1-well cementation zone sleeve, 2-medium transmission channel zone sleeve, 101-sleeve annular space, 102-steel rod, 103-fixing bolt, 104-right angle fixing steel ring, 105-steel rod turning handle, 106-coagulant input hole, 107-T-shaped rubber plug, 108-outer sleeve I, 109-inner sleeve, 110-perforation, 111-solid circular tube, 201-internal circular tube, 202-internal circular tube orifice, 203-ball, 204-groove base, 205-medium transmission channel, 206-outer sleeve II, 3-low-permeability pollution soil sample unit, 4-fracturing/repairing well pipe, 5-loading top plate, 6-air bag packer, 7-coagulation zone, 8-well pipe perforation, and 9-multifunctional sleeve.

Detailed Description

The invention provides a multifunctional casing for a fracturing and permeability-increasing synergic restoration test of low-permeability polluted soil.

The technical solutions provided in the present application will be further described with reference to specific embodiments and accompanying drawings. The advantages and features of the present application will become more apparent in conjunction with the following description.

Example (b):

the multifunctional casing for the fracturing, permeability-increasing and cooperative repair test of the low-permeability polluted soil comprises the following structural components: the device comprises a casing annular space 101, a steel rod 102, a fixing bolt 103, a right-angle fixing steel ring 104, a steel rod rotating handle 105, a coagulant input hole 106, a T-shaped rubber plug 107, a first outer casing 108, an inner casing 109, a perforation 110, a solid circular tube 111, an inner attached circular tube 201, an inner attached circular tube orifice 202, a ball 203, a groove base 204, a medium transmission channel 205 and a second outer casing 206.

As shown in fig. 1, the multifunctional casing for the fracturing, permeability-increasing and cooperative repairing test of low-permeability contaminated soil of the embodiment includes a casing 1 in a well cementation zone and a casing 2 in a medium transmission channel zone; the casing 1 of the well cementation zone and the casing 2 of the medium transmission channel zone are of an integral structure, the casing 1 of the well cementation zone is positioned at the upper part, and the casing 2 of the medium transmission channel zone is positioned at the lower part.

Wherein, well cementation zone sleeve 1 includes: a first outer sleeve 108 and an inner sleeve 109; a gap is arranged between the first outer sleeve 108 and the inner sleeve 109 and is called a sleeve annulus 101; a plurality of rows of perforations 110 are arranged in the outer sleeve 108 along the normal direction, each row of perforations 110 is positioned on the same cross section, the perforations 110 in adjacent rows are vertically staggered, and the perforations in the lower row are positioned on the central line of the connecting line of the adjacent perforations in the upper row; the inner sleeve 109 is not subjected to any hole opening treatment; the bottom end of the casing annular space 101 is rigidly connected and sealed with the inner casing 109 through the first outer casing 108, and the top end of the casing annular space 101 is completely open;

the medium transmission channel region sleeve 2 comprises a second outer sleeve 206, a medium transmission channel 205, an inner attached circular tube 201, a ball 203, a groove base 204 and a steel rod 102; a plurality of medium transmission channels 205 are arranged on the second outer sleeve 206 along the circumferential direction, and the medium transmission channels 205 penetrate through the pipe wall of the second outer sleeve 206; the internal circular tube 201 is arranged in the second outer sleeve 206, the outer wall of the internal circular tube is tightly attached to the inner wall of the second outer sleeve 206, and the internal circular tube orifices 202 with the same shape, size and number as the medium transmission channel 205 are formed;

the bottom of the internal round tube 201 is provided with a downward groove; a groove base 204 is arranged on the inner wall of the second outer sleeve 206; a plurality of balls 203 which are closely arranged in a circle are arranged between the groove base 204 and the groove of the internal round pipe 201; the steel rod 102 is welded on the inner attached circular tube 201, the steel rod 102 extends out of the top of the sleeve along the inner side of the sleeve, the top end of the steel rod 102 is horizontally bent into a steel rod rotating handle 105, the inner attached circular tube 201 can rotate on the groove base 204 provided with the balls 203 by rotating the steel rod rotating handle 105, when the medium transmission channel 205 is overlapped with the orifice 202 of the inner attached circular tube, free medium transmission can be realized, and when the medium transmission channel 205 is completely staggered with the orifice 202 of the inner attached circular tube, the medium transmission channel 205 of the outer sleeve 108 can be closed.

Referring to fig. 3, the use method of the multifunctional casing for the fracture permeability-increasing synergic restoration test of the low-permeability contaminated soil of the embodiment includes the following steps:

the first step is as follows: before the test model box is filled with polluted soil to prepare the low-permeability polluted soil sample unit 3, the multifunctional casing 9 is placed in the center of the test model box in advance, at the moment, the steel rod rotating handle 105 is rotated to close the medium transmission channel 205 of the multifunctional casing 9, the casing annular space 101 of the multifunctional casing 9 is also embedded into the solid circular tube 111, and the two operations are both used for preventing polluted soil particles from entering the multifunctional casing 9 through the medium transmission channel 205 and the perforation 110;

the second step is that: after the low-permeability polluted soil sample unit 3 is prepared, taking out a solid circular tube 111 embedded into the casing annulus 101, sequentially installing a T-shaped rubber plug 107 and a right-angle fixed steel ring 104 at the top end of the casing annulus 101, finally inserting a fixed bolt 103 into the periphery of the right-angle fixed steel ring 104 to seal the top end of the casing annulus 101, then injecting a rapid coagulant into the casing annulus 101 through a coagulant input hole 106, seeping the rapid coagulant onto an outer casing I108 through a perforation 110, and rapidly contacting and coagulating with a peripheral soil body to form a coagulation zone 7, so as to realize well cementation and seepage prevention;

the third step: slowly pumping out the residual quick coagulator by using a vacuum pump, removing a fixing bolt 103, a right-angle fixing steel ring 104 and a T-shaped rubber plug 107, embedding a solid circular tube 111 in the sleeve annular space 101 again, and applying consolidation stress to the low-permeability polluted soil sample unit 3 through a loading top plate 5;

the fourth step: after the consolidation is finished, rotating the steel rod rotating handle 105 to open the medium transmission channel 205, placing the fracturing/repairing well pipe 4 into the multifunctional casing pipe 9, enabling the well pipe perforation 8 to be aligned with the medium transmission channel 205, and injecting gas into the two airbag packers 6 wound on the fracturing/repairing well pipe 4, wherein the pressure in the airbag packers 6 after gas injection is at least 1.5 times of the pressure applied to the fracturing/repairing well pipe 4, so as to ensure the tightness in the fracturing permeation-increasing or in-situ repairing process;

the fifth step: selecting to carry out a fracturing and permeability increasing or in-situ remediation test on the low-permeability polluted soil through a matched facility connected outside the fracturing/remediation well pipe 4;

and a sixth step: after the test is finished, the gas in the air bag packer 6 is slowly released, the fracturing/repairing well pipe 4 and the multifunctional casing pipe 9 are sequentially taken out, and the operations such as cleaning and maintenance are carried out on the fracturing/repairing well pipe 4 and the multifunctional casing pipe 9.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments. Those skilled in the art should appreciate that many modifications and variations are possible in light of the above teaching without departing from the scope of the invention.

Claims

1. A multifunctional sleeve for a low-permeability contaminated soil fracturing and permeability-increasing collaborative restoration test is characterized by comprising: the well fixing area comprises a well fixing area sleeve (1) and a medium transmission channel area sleeve (2); the solid well region sleeve (1) and the medium transmission channel region sleeve (2) are of an integral structure, the solid well region sleeve (1) is positioned at the upper part, and the medium transmission channel region sleeve (2) is positioned at the lower part;

wherein the cementing zone sleeve (1) comprises: a first outer sleeve (108) and an inner sleeve (109); a gap is arranged between the first outer sleeve (108) and the inner sleeve (109) and is called a sleeve annulus (101); a plurality of rows of perforations (110) are arranged in the outer sleeve I (108) along the normal direction, each row of perforations (110) is positioned on the same cross section, and the perforations are uniformly distributed on the wall of the outer sleeve I (108); the perforations (110) of adjacent rows are staggered vertically, and the lower row of perforations are positioned on the central line of the connecting line of the adjacent perforations of the upper row; the inner sleeve (109) is not subjected to any hole opening treatment; the bottom end of the casing annular space (101) is rigidly connected and sealed by a first outer casing pipe (108) and an inner casing pipe (109), and the top end of the casing annular space (101) is completely open;

the bottom of the internal round tube (201) is provided with a downward groove; a groove base (204) is arranged on the inner wall of the second outer sleeve (206); a plurality of balls (203) which are closely arranged in a circle are arranged between the groove base (204) and the groove of the inner attached circular pipe (201); the steel rod (102) is welded on the inner attached circular tube (201), the steel rod (102) extends out of the top of the sleeve along the inner side of the sleeve, the top end of the steel rod (102) is horizontally bent into a steel rod rotating handle (105), the inner attached circular tube (201) can rotate on a groove base (204) distributed with balls (203) by rotating the steel rod rotating handle (105), when the medium transmission channel (205) is superposed with the hole opening (202) of the inner attached circular tube, free medium transmission can be realized, and when the medium transmission channel (205) is completely staggered with the hole opening (202) of the inner attached circular tube, the medium transmission channel (205) of the outer sleeve I (108) can be closed;

the casing annulus (101) may be embedded with a solid circular tube (111), the solid circular tube (111) sized to match the casing annulus (101).

2. The multifunctional casing for the low-permeability polluted soil fracturing permeability-increasing cooperative repair test is characterized in that the casing annulus (101) can be kept hollow, a T-shaped rubber plug (107) is embedded into the top end of the casing annulus, and a right-angle fixed steel ring (104) is covered on the T-shaped rubber plug (107); a coagulant input hole (106) penetrates through the T-shaped rubber plug (107) and the right-angle fixed steel ring (104) and is communicated with a sleeve annulus (101) from the outside; and a plurality of fixing bolts (103) are inserted into the contact area of the right-angle fixing steel ring (104) and the first outer sleeve (108) along the periphery of the pipe, and the fixing bolts (103) penetrate through the right-angle fixing steel ring (104) and are embedded into the first outer sleeve (108) but do not penetrate through the first outer sleeve to ensure that the top end of the annular sleeve (101) is sealed.

3. The multifunctional casing for the fracturing and permeability-increasing synergic restoration test of the low-permeability polluted soil as claimed in claim 1, wherein when used for the fracturing and permeability-increasing synergic restoration test of the low-permeability polluted soil, the multifunctional casing comprises the following steps:

the first step is as follows: before the test model box is filled with the polluted soil to prepare the low-permeability polluted soil sample unit (3), a multifunctional casing (9) is placed in advance at the central position of the test model box, at the moment, a steel rod rotating handle (105) is rotated to close a medium transmission channel (205) of the multifunctional casing (9), and a casing annular space (101) of the multifunctional casing (9) is also embedded into a solid circular tube (111), wherein the two operations are to prevent polluted soil particles from entering the multifunctional casing (9) through the medium transmission channel (205) and a perforation (110);

the second step is that: after the low-permeability polluted soil sample unit (3) is prepared, taking out a solid circular tube (111) embedded into the sleeve annulus (101), sequentially installing a T-shaped rubber plug (107) and a right-angle fixed steel ring (104) at the top end of the sleeve annulus (101), finally inserting a fixed bolt (103) at the periphery of the right-angle fixed steel ring (104) to seal the top end of the sleeve annulus (101), then injecting a rapid coagulant into the sleeve annulus (101) through a coagulant input hole (106), and allowing the rapid coagulant to seep out of an outer sleeve I (108) through a perforation (110) and rapidly contact and coagulate with a peripheral soil body to form a coagulation zone (7), thereby realizing well cementation and seepage prevention;

the third step: slowly pumping out the residual quick coagulator by using a vacuum pump, removing a fixing bolt (103), a right-angle fixing steel ring (104) and a T-shaped rubber plug (107), embedding a solid circular tube (111) in the sleeve annular space (101) again, and applying consolidation stress to the low-permeability polluted soil sample unit (3) through a loading top plate (5);

the fourth step: after consolidation is completed, rotating a steel rod rotating handle (105) to open a medium transmission channel (205), putting the fracturing/repairing well pipe (4) into a multifunctional casing (9), aligning a well pipe perforation (8) with the medium transmission channel (205), and injecting gas into two gas bag packers (6) wound on the fracturing/repairing well pipe (4), wherein the pressure in the gas bag packers (6) after gas injection is at least 1.5 times of the pressure applied in the fracturing/repairing well pipe (4), so as to ensure the tightness in the fracturing infiltration or in-situ repairing process;

the fifth step: selectively developing a fracturing and permeability increasing or in-situ remediation test of low-permeability polluted soil through a matched facility connected outside the fracturing/remediation well pipe (4);

and a sixth step: after the test is finished, the gas in the air bag packer (6) is slowly released, the fracturing/repairing well pipe (4) and the multifunctional casing pipe (9) are sequentially taken out, and the fracturing/repairing well pipe and the multifunctional casing pipe are cleaned and maintained.