KR20160024485A

KR20160024485A - Enhanced Coalbed Gas Production Process

Info

Publication number: KR20160024485A
Application number: KR1020140111247A
Authority: KR
Inventors: 백영순; 조원준; 이현찬; 주우성; 모용기; 이지혜; 백현선; 안문성
Original assignee: 한국가스공사
Priority date: 2014-08-26
Filing date: 2014-08-26
Publication date: 2016-03-07

Abstract

The present invention relates to an improved method of producing coal bed gas, characterized in that vaporization pressure of liquid carbon dioxide is used in injecting carbon dioxide into the coal bed. According to the present invention, there is no need to use a separate compressor, so energy consumption is low, and pressure and flow rate can be adjusted by using a buffer tank, which is advantageous for application of commercial diatoms.

Description

Improved Coalbed Gas Production Process < RTI ID = 0.0 >

The present invention relates to an improved method for producing coal bed gas.

Coal has a function of adsorbing gas by its fine clearance structure, and usually, a large amount of hydrocarbon gas containing methane gas as a main component is packed in the coal layer in the ground. Since the main component of coal bed gas is methane, it is generally called coal bed methane gas or coal bed methane gas (CBM). Coal bed methane gas (CBM) is generated in the course of the plant's conversion to coal during the geological period and is present in the coal bed with the coal attached to the molecule or liberated in the pore.

The technology that captures and develops methane gas present in the coal bed and utilizes it as a resource not only minimizes the problems in global warming and environment but also is a way to solve the resource depletion problem which is becoming a global issue, Its importance continues to grow.

As a method for recovering the methane gas present in the coal layer, a process of injecting water into the coal layer is widely known. However, this method poses another problem due to disposal or disposal of a large amount of discharged water.

On the other hand, coal has a property of adsorbing carbon dioxide in a number of times of methane. When methane gas contained in coal is replaced with carbon dioxide, carbon dioxide, which is one of the greenhouse gases that cause global warming, And it is also advantageous that methane gas, which is a clean energy, can be recovered by substituting for carbon dioxide.

Therefore, studies for efficiently recovering methane gas, which is contained in a large amount in the coal bed, and using it as a fuel gas in other processes are still being conducted. For example, Japanese Patent Application Laid-Open No. 2004-3326 discloses a process of pressurizing supercritical carbon dioxide into a coal layer to recover gas. However, this method requires a high pressure because the carbon dioxide must remain in the supercritical state when it reaches the coal bed, and since the coal bed itself must withstand the pressure of the pressurized supercritical carbon dioxide, There is a limit to apply to coal beds.

In addition, in Korea, research for development of CBM is biased toward exploration drilling and test production, and research on displacement and flow mechanism for field-scale recovery enhancement technology, design of collection system based on a large number of production conditions, Research on key technologies such as technology is insufficient.

It is an object of the present invention to provide a method for producing coal bed gas which is advantageous for practical application because it is easy to control the process while reducing energy cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-

(a) locating a coalbed having a gas secured to the coal;

(b) providing at least one production well in communication with the coal bed;

(c) installing a carbon dioxide injection well communicating with the coal layer at a position spaced apart from the production well;

(d) vaporizing the liquid carbon dioxide and injecting the liquid carbon dioxide through the carbon dioxide injection well; And

(e) recovering the gas desorbed from the coal by the carbon dioxide injected into the coal seam through the production well.

Wherein in step (d), the carbon dioxide is injected into the carbon dioxide injection well by the vaporization pressure of the liquid carbon dioxide.

According to a preferred embodiment, in step (d), the carbon dioxide is injected into the carbon dioxide injection well by the vaporization pressure of the liquid carbon dioxide.

According to one embodiment, the vaporization pressure and the flow rate of the liquid carbon dioxide may be adjusted in a buffer tank installed at a carbon dioxide injection static front end.

At this time, the pressure to be regulated in the buffer tank may be 5 to 10 MPa and the flow rate may be 100 to 300 kg / h.

According to one embodiment, the liquid carbon dioxide may be stored in one or more storage tanks.

In addition, the storage tank may be maintained at a pressure of 1 to 2.5 MPa and a temperature of -30 to -10 DEG C to maintain the carbon dioxide in a liquid state.

According to one embodiment, the liquid carbon dioxide transferred from the storage tank may be vaporized via a vaporizer and then supplied to a buffer tank.

At this time, the vaporizer may be adjusted to a pressure of 5 to 10 MPa and a temperature of 40 to 80 ° C.

According to one embodiment, the liquid carbon dioxide from the storage tank may be transferred to the vaporizer by a liquid pump.

Also, according to one embodiment, the product pellet and the carbon dioxide pellet may be spaced 100 to 500 m apart.

The method according to the present invention enables capturing methane gas, sail gas, and natural gas buried in the basement layer to be secured as fuel resources of the country. In addition, CO ₂ , which is known to seriously affect global warming, It also has the effect of storing CO ₂ in the basement. Particularly, since the method of the present invention is injected by using the vaporization pressure of liquid CO ₂ , energy consumption can be significantly reduced compared with the process of injecting gaseous CO ₂ by using a compressor, It can be easily applied to an actual process.

1 is a schematic view for explaining the principle of a coal bed gas production method using carbon dioxide.
2 is a schematic device configuration diagram according to an embodiment of the present invention.
3 is a process flow diagram according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It should be understood, however, that the present invention is not intended to be limited to any particular embodiment, but is to be understood as all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the present invention will be described in more detail.

The gas production in the coal bed is calculated by taking into consideration the pressure gradient across the production facilities such as the production line, the production line, the wellhead, the separator, etc., depending on the production facility system and their operating conditions. . Also, considering the inflow pressure and temperature condition necessary for the production operation plan and refinery facility design, optimum operating pressure and temperature condition for each production facility should be set for each node separately. A series of production systems from the coal bed to the refineries are represented by the collection system, and designing and constructing them appropriately is an essential technology for the coal bed recovery business.

The methane recovery process, known as CBM or ECBM, generally extracts gas through a pipeline installed in the coal bed, and the extracted gas is eventually recycled through collection and purification processes. The produced CBM contains nitrogen (N ₂ ), oxygen (O ₂ ), carbon dioxide (CO ₂ ), water vapor (H ₂ O), hydrogen sulfide (H ₂ S) and the like. Engineering technologies such as enhancement technology, capture technology, and refining technology are inevitably needed to make this a resource. In other words, the CBM produced is mixed with various gas components and selectively purified to obtain high-efficiency methane gas. In addition, it can be converted into various energy resource types by refining it according to the feed composition by varying the purification process according to the final target material.

A method for producing a coal bed gas according to the present invention comprises:

(a) determining the position of the carbonaceous layer having the gas fixed to the carbonaceous material;

(b) providing at least one production well in communication with the coal bed;

(e) recovering the gas desorbed from the coal by the carbon dioxide injected into the coal seams through the production well.

As shown in FIG. 1, the present invention provides a process for recovering and recovering hydrocarbon gas (mainly methane gas) fixed to a coal layer by supplying carbon dioxide into a coal bed by installing a carbon dioxide injection well at a position spaced a predetermined distance from the production well . Coal is more resistant to carbon dioxide than hydrocarbons such as methane.

1 shows a carbon dioxide injection pipe 11 penetrating the coal layer 1 from an indicator 2 as a means for pressurizing carbon dioxide into an underground coal layer 1 and extracting a gas component from the coal layer 1, And a carbon dioxide injecting device 12 for injecting carbon dioxide into the coal layer 1 from the pipe 11 at a predetermined pressure.

Here, the carbon dioxide injector 12 extracts the gas component fixed to the carbonitride layer 1 by injecting carbon dioxide of a predetermined purity into the carbonitride layer 1 at a predetermined pressure.

In addition, the gas recovery pipe 31 can be installed at a position relatively far from the carbon dioxide injector 12, preferably at a low depth.

As shown in FIG. 1, when the coal layer 1 is inclined, it is preferable to install the carbon dioxide injection pipe at a deeper depth and to install the gas recovery pipe 31 at a shallow place, have. The gas recovery device 32 may be a device that recovers the gas that is naturally produced or a device that recovers by using forced suction means.

In the present invention, it is characterized in that to the press by the vaporization of the liquid carbon dioxide to a pressure in an underground coal seam, extracting the gas fixed to the coal.

The coal layer in the present invention refers to a stratum (coal layer) composed of coal existing in the ground, and its kind is not particularly limited. Examples of the coal layer include bituminous coal, lignite, low quality coal, and anthracite coal.

The depth of the carbonaceous layer is not particularly limited, but may be a carbonaceous layer having a depth of about 500 m to 3000 m. In the present invention, the gasification pressure is used when injecting the carbon dioxide injection pellets, and since the carbon dioxide does not need to be in a special state inside the coal pellet, the depth of the carbonitride layer is not limited.

In the present invention, a carbon dioxide injection pipe reaching the coal layer is installed, and high-purity carbon dioxide is injected at a pressure and a temperature sufficient to push out the gas fixed to the coal layer.

In the present invention, the temperature and the pressure of the carbon dioxide in the carbon dioxide injection well are, for example, in the case where the depth of the coal layer 1 at the pressure point is about 1000 m, for example, the carbon dioxide having a purity of 99.9% 10 MPa, a temperature of about 20 to 40 DEG C, most preferably about 7 MPa, and a temperature of about 30 DEG C.

When reaching the coal bed, the pressure of the carbon dioxide can be adjusted to be about 5 to 10 MPa, preferably about 6 to 8 MPa, and most preferably about 7 MPa. When liquid carbon dioxide is injected under the above conditions, pressurization is possible by the pressure of vaporizing from the liquid phase.

Preferably, the high-purity liquid carbon dioxide is injected at a predetermined pressure and temperature to extract the gas fixed on the coal. The high purity is about 99% or more, preferably 99.9% or more.

Carbon dioxide injection can be continuous or intermittent. The injection interval or the injection amount can be determined in consideration of the state of the coal layer.

By pressurizing and infiltrating carbon dioxide into the coal seam, the gas component can be extracted from the coal. It is preferable that the pressurized flow rate of the carbon dioxide is appropriately controlled so that carbon dioxide is rarely contained in the recovered coal bed gas component. That is, the carbon dioxide permeated into the coal layer is preferably immobilized on the coal layer.

Such high-purity carbon dioxide can be separated and recovered from a thermal power plant or a waste gas of a factory. The recovery and recovery of carbon dioxide from such a facility is currently carried out, and the recovered carbon dioxide is dumped into the sea or the ground in some cases. In the invention, such carbon dioxide can be used as it is, or the purity can be increased to some extent. In addition, high-purity carbon dioxide can be relatively easily obtained by an amine method in which the product is absorbed and recovered by an amine such as ethanolamine. The method of obtaining liquid carbon dioxide can be carried out by any method known in the art without any specific description.

In the present invention, one or more carbon dioxide injection pits may be provided per one carbon monoxide production process. The method is not particularly limited as far as the pressurization of the supercritical carbon dioxide into the coal bed can effectively infiltrate carbon dioxide into the coal as much as possible.

It is preferable that the carbon dioxide injection pellets are separated from the production pellets by about 100 to 500 m, preferably about 100 to 300 m. If the distance is too close, the carbon dioxide may not be sufficiently adsorbed on the carbon layer to be removed, The desorption effect may not be sufficient.

In particular, since the present invention is injected into the carbon dioxide injection nozzle using the vaporization pressure of liquid carbon dioxide, the energy consumption can be reduced as compared with the process of injecting gaseous carbon dioxide using a compressor. In addition, the buffer pressure can be easily controlled by utilizing the buffer tank.

That is, according to one embodiment, in step (d), the carbon dioxide may be injected into the carbon dioxide injection well by the vaporization pressure of the liquid carbon dioxide. At this time, since the gasification pressure is about 7 MPa at a temperature of 30 ° C, energy can be reduced because it can be injected into the injection well without using a separate compressor.

According to another embodiment, it is also possible to control the vaporization pressure and the flow rate of liquid carbon dioxide by placing a buffer tank at the carbon dioxide injection front end.

2 is a device configuration diagram according to an embodiment of the present invention. 2 is merely illustrative of a preferred embodiment, and the scope of the present invention is not limited thereto.

The liquid carbon dioxide transported from the liquid carbon dioxide transport vehicle is stored in the storage tanks (V-201A, V-201B). It is preferable to install one or more storage tanks.

The storage tank may be maintained at a pressure of from about 1 to about 2.5 MPa and a temperature of from about -30 DEG C to about -10 DEG C, preferably from about 1.0 to about 2.5 MPa, and at a temperature of from about -20 DEG C to -10 DEG C Most preferably about 2.1 MPa, and a temperature of about -17.8 < 0 > C.

The liquid carbon dioxide from the storage tanks V-201A and V-201B can be transferred to the vaporizer E-201 by the pump P-201. The vaporizer is operated at a temperature and pressure capable of vaporizing liquid carbon dioxide. Preferably at a pressure of about 5 to 10 MPa, preferably at a pressure of about 6 to 8 MPa, most preferably at 7 MPa, and at a temperature of about 40 to 80 DEG C, preferably about 60 DEG C.

In the vaporizer E-201, the vaporized carbon dioxide may be supplied directly to the carbon dioxide injection tank, but in a preferred embodiment, it may be supplied to the buffer tank V-202.

In the buffer tank (V-202), the pressure of carbon dioxide is 5 to 10 MPa, preferably 6 to 8 MPa, most preferably about 7 MPa, and the flow rate is about 100 to 300 kg / h, 250 kg / h, and most preferably about 200 kg / h.

According to another embodiment, the gas component recovered by the carbon dioxide indentation may be recovered in the state of coexistence with the groundwater, or may be recovered as gasified. In either method, only the carbon dioxide is selectively adsorbed and immobilized on the coal seams by recovering the carbon monoxide after the carbon monoxide has been infiltrated, thereby recovering the gas component whose carbon dioxide content has decreased or has been removed.

As shown in FIG. 3, the CBM recovered with water can be transferred to the purification apparatus via the gas-liquid separator.

In the case of using vaporization pressure of liquid carbon dioxide, energy saving is expected compared with a process of injecting carbon dioxide using a compressor. It is also expected that the efficiency of the process will increase if buffer tanks are used.

As described above, since the method of the present invention is injected using the vaporization pressure of liquid CO _2, the method of the present invention can significantly reduce energy consumption compared to the process of injecting gaseous CO ₂ using a compressor In addition, since the injection pressure can be easily controlled by utilizing the buffer tank, it can be effectively applied to the actual process.

1 layer
11 Carbon dioxide injection tube
12 CO2 injection system
31 Gas recovery pipe
32 Gas recovery device
V-201A, V-201B storage tank
P-201 pump
E-201 vaporizer
V-202 Buffer Tank

Claims

(a) determining the position of the carbonaceous layer having the gas fixed to the carbonaceous material;
(b) providing at least one production well in communication with the coal bed;
(c) installing a carbon dioxide injection well communicating with the coal layer at a position spaced apart from the production well;
(d) vaporizing the liquid carbon dioxide and injecting the liquid carbon dioxide through the carbon dioxide injection well; And
(e) recovering the gas desorbed from the coal by the carbon dioxide injected into the coal seam through the production well.

The method according to claim 1,
Wherein in step (4) the carbon dioxide is injected into the carbon dioxide injection well by the vaporization pressure of the liquid carbon dioxide.

3. The method of claim 2,
Wherein the vaporization pressure and the flow rate of the liquid carbon dioxide are adjusted in a buffer tank installed at a carbon dioxide injection static front end.

The method of claim 3,
Wherein the pressure in the buffer tank is 5 to 10 MPa and the flow rate is 100 to 300 kg / h.

The method according to claim 1,
Wherein the liquid carbon dioxide is stored in one or more storage tanks.

6. The method of claim 5,
Wherein the storage tank maintains carbon dioxide in a liquid state at a pressure of from 1 to 2.5 MPa and a temperature of from -30 to -10 占 폚.

6. The method of claim 5,
Wherein the liquid carbon dioxide transferred from the storage tank is vaporized via a vaporizer and then supplied to a buffer tank.

8. The method of claim 7,
Wherein the vaporizer is regulated at a pressure of 5 to 10 MPa and a temperature of 40 to 80 占 폚.

6. The method of claim 5,
Wherein the liquid carbon dioxide from the storage tank is delivered to the vaporizer by a liquid pump.

The method according to claim 1,
Wherein the production pitch and the carbon dioxide injection pitch are spaced apart by a distance of 100 to 500 meters.