JP2006045839A - Well device having fluid injecting and recovering functions, and method of setting the well device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a well device which singly has both a function of injecting liquid or gaseous carbon dioxide into an underground coal layer and a function of recovering gaseous methane embedded in the coal layer, and to provide a method of setting the well device. <P>SOLUTION: The well device having the fluid injecting and recovering functions carries out injection of carbon dioxide (CO<SB>2</SB>) into the coal layer 31 in which gaseous methane (CH<SB>4</SB>) is embedded, then substitutes the carbon dioxide for the methane, and recovers the methane in the coal layer. The well device is formed of a main well 20 excavated from the ground surface 30 to the coal layer, a branch well 25 branched from some midpoint of the main well 20 and excavated in the coal layer 31 along a direction of the coal layer, injection port members 21, 23 arranged in the main well 20, for injecting carbon dioxide supplied from the ground side, into the coal layer 31, and recovery port members 15, 26 arranged in the main well and the branch well 25, for recovering methane to the ground side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides an anti-well apparatus equipped with a fluid injection / recovery function for injecting liquid or gaseous carbon dioxide into an underground coal seam and recovering gaseous methane buried in the coal seam to the ground; It is related with the installation method of the well apparatus. More specifically, in one well, the function of injecting liquid or gaseous carbon dioxide into the underground coal seam, and the function of recovering gaseous methane extruded from the coal seam by injecting carbon dioxide The present invention relates to a well apparatus equipped with a fluid injection / recovery function and a method for installing the well apparatus.

Although the amount varies depending on the conditions of the coal seam, a considerable amount of methane (CH ₄ ) is adsorbed and incorporated in the coal seam existing underground. Methane is a useful substance as a fuel or chemical raw material, and methods for collecting and effectively using methane present in coal seams have been studied and developed.
As a method for recovering methane (CH ₄ ) in the coal seam, there is a method in which a well penetrating into the coal seam by boring from the ground surface is provided, and methane is collected by self-injection or by pumping water to reduce pressure. This method is a relatively easy method, but has a problem that the recovery rate of methane is low and only about 50% of the reserves can be collected.

On the other hand, carbon dioxide (CO ₂ ), whose emissions are increasing in recent years, has become a problem as one of the causes of global warming, and various immobilization treatments and reduction methods by effective use have been proposed. However, it is hardly put into practical use.
In addition, by utilizing the difference in adsorption between the carbon dioxide and methane to the coal bed, carbon dioxide is injected into the coal bed and built in, and as a result, the methane absorbed in the coal bed is driven out and recovered. The technique which performs is proposed (for example, patent document 1). However, in this technology, there are a plurality of injection holes (injection wells) for injecting carbon dioxide into the coal seam from the ground side and recovery holes (production wells) for recovering methane from the coal seam to the ground side. It was necessary to drill a well. However, enormous costs were required to drill two wells, and the period for drilling and installing the well apparatus was long. Therefore, there has been a demand for the development of a well device that can perform the function of carbon dioxide injection and the function of methane recovery with a single borehole.
Japanese Patent No. 3283975

  The present invention has been made based on the technical background and social background described above, and achieves the following objects.

  An object of the present invention is to provide a well apparatus having a fluid injection / recovery function that combines a function of injecting gaseous or liquid carbon dioxide with a single well apparatus and a function of recovering gaseous methane. And it is providing the installation method of the well apparatus.

The present invention takes the following means in order to solve the above-described problems.
The well apparatus having the fluid injection / recovery function of the present invention 1
A well device for injecting carbon dioxide into a coal bed containing gaseous methane and recovering the methane expelled from the coal bed,
A main well drilled from the surface side to the coal bed, a branch well branched from the middle of the main well, and drilled in the coal bed, provided in the main well, the coal bed side A pressure inlet portion in the end portion and / or near the end portion, and provided in the main well and the branch well, and a pressure inlet member that discharges and presses the carbon dioxide supplied from the ground side into the coal bed And a recovery port member that has a recovery port portion inside the branch well extending from the branched position and recovers the methane substituted with the carbon dioxide in the coal bed to the ground side. .

The well apparatus equipped with the fluid injection / recovery function of the present invention 2 is the present invention 1,
The main well is composed of a large-diameter portion excavated to a desired depth position in the upper part of the coal bed or near the upper part of the coal bed, and a small-diameter part excavated in the coal bed below the large-diameter part. And
The recovery port member is provided in the large-diameter portion and has one end side connected to the methane recovery portion on the ground side and the branch well, and one end side is connected to the casing and has the recovery port portion It consists of a sub casing and
The pressure inlet member extends through the casing to the small diameter portion, and is connected to a first pipe whose one end is connected to the carbon dioxide supply section on the ground side, and to the other end of the first pipe, It is characterized by being comprised from the 2nd pipe which has the said pressure inlet part.

The well apparatus having the fluid injection / recovery function of the third aspect of the present invention is the second aspect of the present invention.
The small diameter portion is excavated so as to be inclined at a predetermined angle and / or partially bent with respect to the large diameter portion.

The installation method of the well apparatus provided with the fluid injection / recovery function of the present invention 4
A method of installing a well apparatus for injecting carbon dioxide into a coal bed containing gaseous methane and recovering the methane expelled from the coal bed,
A main well is excavated from the surface side toward the coal bed, branched from the middle of the main well, and a branch well formed in the coal bed is excavated and supplied to the main well from the ground side. An inlet member having an inlet portion for releasing and injecting carbon dioxide into the coal bed is provided, and the main well and the branch well are provided inside the branch well extending from the branched position. A recovery port member having a recovery port portion for recovering the methane substituted with the carbon dioxide in a coal bed to the ground side is provided.

The installation method of the well apparatus having the fluid press-fitting / recovery function of the present invention 5 is the present invention 4,
The main well has a large-diameter portion excavated from the ground surface to a desired depth position in the upper part of the coal bed or in the vicinity of the upper part of the coal bed, and a small-diameter part excavated in the coal bed below the large-diameter part. Consisting of
After excavating the large diameter portion, a casing connected to the methane recovery unit on the ground side is installed in the large diameter portion, and a small diameter portion having a smaller diameter than the large diameter portion in the coal layer below the large diameter portion. The branch well is branched from the middle of the large-diameter portion and formed along the coal bed, and one end side of the branch well is connected to the casing, and the recovery port portion is A second casing having a secondary casing having a secondary casing extending through the casing to the small-diameter portion, having one end connected to a ground-side carbon dioxide supply section, and the other end having the pressure inlet section. A first pipe connected to the pipe is provided.

The installation method in the well device having the fluid injection / recovery function of the present invention 6 is the present invention 5,
The small diameter portion is excavated so as to be inclined at a predetermined angle and / or partially bent with respect to the large diameter portion.

  In the present invention, by installing one well device, adsorption (absorption) / immobilization of carbon dioxide in the coal bed and recovery of methane buried in the coal bed and substituted for carbon dioxide are performed. Useful functions can be performed at a high immobilization rate and a high recovery rate, so that practical use can be achieved. In addition, the installation period of the well apparatus can be shortened, the installation cost can be reduced, etc., and the economic effect is also great.

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing a well device 1 of the present invention.
As shown in FIG. 1, the well 10 is excavated in the ground 32 from the surface 30 side. The well 10 is composed of a main well 20 and a branch well 25 branched from the middle of the main well 20.
In the main well 20, the large-diameter portion 20a is excavated in a vertical direction, a substantially vertical direction, or a slight inclination to a desired depth position in the upper part of the coal bed 31 and in the vicinity of the upper part (including the upper part of the coal bed 31). In this embodiment, the large diameter portion 20 a is excavated to the upper part of the coal bed 31. A small-diameter portion 20b having a smaller diameter than the large-diameter portion 20a is excavated on the lower end side. The small diameter portion 20b is excavated in the coal layer 31 along the direction (direction) of the coal layer 31 to a desired depth (or a desired length) while controlling the direction and the inclination. In this embodiment, the small-diameter portion 20b is excavated as an inclined well so as to be curved or partially bent. The small-diameter portion 20b may be anything that is excavated so as to be inclined at a predetermined angle and / or partially bent with respect to the large-diameter portion 20a. Further, it may be excavated substantially parallel to the ground surface 30.

A casing 15 is installed in the large diameter portion 20 a of the main well 20. In the upper part of the casing 15, a wellhead part 11 and a joint part 12 are provided. The joint part 12 is connected to the piping of the methane recovery part 51 via a valve (open / close valve) 17. A first pipe 21 is provided inside the casing 15, and one end of the first pipe 21 extends through the casing 15 to the small diameter portion 20 b side of the main well 20. On one end side of the first pipe 21, a packer 22 and a second pipe 23 having a hole in the outer peripheral portion are provided. In this embodiment, the pressure inlet member is constituted by the first pipe 21, the second pipe 23, and the like. The packer 22 can be brought into close contact with the well wall of the small diameter portion 20b when the pressure fluid is supplied and expands. The second pipe 23 has a hole 23a such as a slit shape or a round shape on the outer peripheral portion. In this embodiment, the hole 23a forms a pressure inlet portion. The other end of the first pipe 21 is connected to the carbon dioxide supply unit 50 via a valve (open / close valve) 16. That is, the carbon dioxide (CO ₂ ) supplied from the carbon dioxide supply unit 50 on the ground side is discharged and injected into the coal layer 31 from the hole 23 a (pressure inlet portion) of the second pipe 23 through the first pipe 21. In addition, the pressure inlet part should just be provided in the edge part by the side of the coal bed 31, and / or the edge part, and the hole etc. were formed so that a carbon dioxide can be discharge-pressed into the coal bed 31.

  A cement filler 32 a is filled between the well wall of the large-diameter portion 20 a of the main well 20 and the casing 15. Similarly, the cement filler 32b is also filled between the well wall of the small diameter portion 20b of the main well 20 and the first pipe 21.

The branch well 25 is excavated in the coal bed 31 to a desired depth (or a desired length) along the direction of the coal bed 31 while the direction and inclination are controlled. A sub casing 26 having a slit 26a or a round hole 26a is inserted into the branch well 25. The sub casing 26 has a hole 26a such as a slit shape or a round shape on the outer peripheral portion, and this hole 26a forms a recovery port portion. Then, the hole 26a is to recover the gaseous methane have been pushed out by the adsorption of carbon dioxide (CO ₂₎ from coal layer 31 (CH _4). The sub casing 26 is connected to the casing 15 and recovers methane (CH ₄ ) to the methane recovery section 51 via the joint section 12 and the valve 17. In this embodiment, the recovery port member is formed by the casing 15, the sub casing 26, and the like.
In addition, it is preferable that the hole (collection port part) 26a of the subcasing 26 and the hole (pressure inlet part) 23a of the second pipe 23 are separated as much as possible by a predetermined distance or more in the same or substantially the same coal layer. .

  In the casing 15, a pumping pipe 40 is provided for discharging the groundwater in the casing 15 to the outside. The pumping pipe 40 is connected to a pumping pump (not shown) via a valve (open / close valve) 41. Has been.

The installation method of the well apparatus 1 is demonstrated.
(1). The large-diameter portion 20a of the main well 20 is excavated from the ground surface 30 to a desired depth above the coal bed 31 by a normal drilling method. The casing 15 is installed in the large diameter portion 20 a, and the cement filler 32 a is filled between the pit wall of the large diameter portion 20 a and the outer peripheral portion of the casing 15.
(2). The small-diameter portion 20b, which is smaller in diameter than the large-diameter portion 20a of the main well 20, has a desired depth (or desired length) along the direction of the coal bed 31 in the coal bed 31 while controlling the direction and inclination of the well. The small-diameter portion 20b of the main well 20 is excavated in a direction-oriented manner. In this embodiment, the small-diameter portion 20b is an inclined well that is partially bent. This excavation method is a known technique such as inclined digging, and further description thereof is omitted.

(3). A whip stock (not shown) or the like is installed below the casing 15 installed in the item (1), and a hole is made on the side of the casing 15 with a window mill or the like, and the branch well 25 is excavated therefrom. This branch well 25 also excavates the inside of the coal bed 31 to a desired depth (or a desired length) along the direction of the coal bed 31 while controlling the direction and inclination. The technique for excavating the branch well 25 is also a known technique such as a multi-leg excavation method or a multilateral well, and further description thereof is omitted. A sub casing 26 is inserted into the branch well 25.
(4) The whip stock or the like installed in the casing 15 is collected and the large diameter portion 20a of the main well 20 is finished.

(5) A tool with a packer 22 attached to the tip of the first pipe 21 and a second pipe 23 attached to the tip of the packer 22 is inserted into the small diameter portion 20 b of the main well 20.
(6) A pressure fluid is supplied to the packer 22 to expand the outer peripheral portion, and to closely contact the well wall of the small diameter portion 20b.
(7) The bottom of the casing 15 between the outer peripheral portion of the first pipe 21 and the small-diameter portion 20b is filled with a cement filler 32b such as cement slurry.
The well apparatus 1 as shown in FIG. 1 is installed by performing the installation work of this procedure.

A method for replacing carbon dioxide (CO ₂ ) and methane (CH ₄ ) in the coal bed 31 will be described.
Gaseous methane is adsorbed (absorbed) in the fine holes on the surface of the coal in the coal layer 31. That is, gaseous methane is buried in the coal layer 31. When carbon dioxide is injected here, methane having a large molecule is expelled and carbon dioxide having a small molecule is adsorbed (absorbed) (for example, at least two molecules of carbon dioxide are absorbed and immobilized per molecule of methane. Is replaced by carbon dioxide). That is, it is considered that substitution of methane and carbon dioxide is performed due to the difference in adsorptivity to coal.

The valve 16 and the valve 17 of the well device 1 are changed from the closed state to the open state. Gaseous or liquid carbon dioxide (CO ₂ ) is supplied in the direction of arrow A from the carbon dioxide supply unit 50 to the first pipe 21. Gaseous or liquid carbon dioxide supplied to the first pipe 21 is discharged / pressed in the direction of arrow B from the hole 23a formed in the second pipe 23 into the coal layer 31. In the coal layer 31, since carbon dioxide has better adsorptivity than methane (CH ₄ ), carbon dioxide is adsorbed on the coal layer 31, and gaseous methane pushed out to the carbon dioxide is released from the coal layer 31. That is, in the coal bed 31, carbon dioxide and methane are replaced.

The liberated methane flows in and is collected in the direction of arrow C from the hole 26a formed in the sub casing 26. The recovered methane flows in the direction of arrow D through the casing 15, the joint portion 12, and the valve 17, and is recovered by the methane recovery portion 51 on the ground. Thus, in the present invention, methane (CH ₄ ) can be recovered at a recovery rate that greatly exceeds the recovery rate of the prior art.
Although groundwater or the like may flow into the casing 15, it is discharged by a pumping pump (not shown) through the pumping pipe 40 and the valve 41.

As mentioned above, although embodiment of this invention was described, it cannot be overemphasized that it is not limited to description of this embodiment.
In the above-described embodiment, the description has been given by digging a branch well in an inclined direction, but it may be excavated in another direction such as a horizontal direction. That is, it is only necessary to excavate in an arbitrary direction in the coal bed where it is determined that replacement can be most efficiently performed.
Moreover, although it demonstrated by the form which provided the small diameter part, the pressure inlet part, etc. of the main well, you may provide several small diameter parts, an inlet part, etc. of a main well. Furthermore, although the description has been given in a form in which one branch well and one recovery port are provided, a plurality of branch wells and a plurality of recovery ports may be provided.

Further, the main well and the branch well may not be captured on the same plane, but may be one in which an inclined well is drilled in an arbitrary direction.
In addition, the description has been given in the form in which one casing is provided in the large-diameter portion of the boring well and the space between the outer wall of the large-diameter portion and the casing is filled with the cement filler. It is good also as a thing of the structure which provided the casing and was filled with the cement filling body between the outer peripheral part of the innermost casing from the well wall of a large diameter part. For example, a structure in which a plurality of nested casings such as double and triple are provided in the large diameter portion, and the space between the large diameter well wall and the outer peripheral portion of the innermost casing is filled with a cement filler. It may be. In this case, it is preferable that the large diameter portion is also excavated into a plurality of stages.

  In addition, it goes without saying that various forms and shapes can be used without departing from the object and spirit of the present invention.

It is explanatory drawing which showed the outline | summary of the well apparatus provided with the fluid press-fit and collection | recovery function of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Well apparatus 10 provided with fluid injection | pouring and collection | recovery function ... Well 11 ... Wellhead part 12 ... Joint part 15 ... Casing 16, 17, 41 ... Valve (open / close valve)
20 ... main well 20a ... large diameter part 20b ... small diameter part 21 ... first pipe 22 ... packer 23 ... second pipe 23a ... hole (pressure inlet part)
25 ... Branch well 26 ... Sub casing 26a ... Hole (recovery port)
DESCRIPTION OF SYMBOLS 30 ... Ground 31 ... Coal bed 32a, 32b ... Cement filler 50 ... Carbon dioxide supply part 51 ... Methane recovery part

Claims (6)

A well device for injecting carbon dioxide (CO ₂ ) into a coal bed (31) containing gaseous methane (CH ₄ ) and recovering the methane expelled from the coal bed (31). ,
A main well (20) drilled from the surface (30) side to the coal bed;
A branch well (25) branched from the middle of the main well (20) and excavated in the coal bed (31);
It is provided in the main well (20) and has a pressure inlet in the end and / or near the end on the coal bed side, and releases the carbon dioxide supplied from the ground side to the coal bed (31). Pressure inlet members (21, 23) to be press-fitted,
The main well (20) and the branch well (25) are provided with a recovery port in the branch well (25) extending from the branched position, and the coal well (31) A well apparatus having a fluid injection / recovery function comprising a recovery port member (15, 26) for recovering the methane substituted for the carbon dioxide to the ground side. A well apparatus having a fluid injection / recovery function according to claim 1,
The main well (20) includes a large diameter portion (20a) excavated to a desired depth position in the upper part of the coal bed (31) or in the vicinity of the upper part of the coal bed, and the lower part of the large diameter part (20a). A small diameter portion (20b) excavated in the coal bed (31),
The recovery port member is provided in the large-diameter portion (20a), and has one end connected to the methane recovery portion (51) on the ground side and the branch well. A side casing connected to the auxiliary casing (26) having the recovery port,
The pressure inlet member extends through the casing (15) to the small diameter portion (20b), and has a first pipe (21) having one end connected to the ground-side carbon dioxide supply portion (50). And a second pipe (23) connected to the other end of the first pipe (21) and having the pressure inlet portion. Well equipment. A well device having a fluid injection / recovery function according to claim 2,
The small diameter portion (20b) is excavated so as to be inclined at a predetermined angle and / or partially bent with respect to the large diameter portion (20a). Well equipment provided. A method of installing a well apparatus for injecting carbon dioxide (CO ₂ ) into a coal bed in which gaseous methane (CH ₄ ) is buried and recovering the methane expelled from the coal bed,
Excavating the main well (20) from the surface side toward the coal bed,
Branching from this main well, drilling a branch well (25) formed in the coal bed,
The main well is provided with an inlet member (21, 23) having an inlet portion for discharging and injecting the carbon dioxide supplied from the ground side into the coal bed,
The main well and the branch well have a recovery port for recovering the methane substituted with the carbon dioxide in the coal bed to the ground side inside the branch well extending from the branched position. A method for installing a well apparatus having a fluid injection / recovery function, characterized in that a mouth member (15, 26) is provided. It is the installation method of the well apparatus provided with the fluid injection / recovery function according to claim 4,
The main well has a large-diameter portion excavated from the ground surface to a desired depth position in the upper part of the coal bed or in the vicinity of the upper part of the coal bed, and a small-diameter part excavated in the coal bed below the large-diameter part. Consisting of
After excavating the large diameter part, a casing (15) connected to the ground side methane recovery part (51) is installed in the large diameter part,
Excavating a small diameter portion smaller than the large diameter portion in the coal layer below the large diameter portion,
Branching from the middle of the large diameter part, excavating the branch well formed along the coal bed,
The branch well is provided with a sub-casing (26) having one end connected to the casing and having the recovery port,
A second pipe (23) that extends through the casing to the small-diameter portion, has one end connected to the ground-side carbon dioxide supply unit (50), and the other end has the pressure inlet. The first pipe (21) connected to the borehole) is provided. A method for installing a well apparatus having a fluid injection / recovery function. It is the installation method of the well apparatus provided with the fluid injection / recovery function according to claim 5,
The small diameter portion is excavated so as to be inclined at a predetermined angle and / or partially bent with respect to the large diameter portion. Installation method.

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