CN104727802B - Subterranean coal penetrates method - Google Patents

Abstract

The invention relates to an underground coal seam penetration method, which is used to penetrate a coal seam between a prefabricated passage during underground coal gasification and a burnt-out area, the passage is formed by extending directional holes on the ground in the underground coal seam, and the passage The end of the channel is close to the burn-out area, an injection pipe is arranged in the directional hole, and gas is injected into the vicinity of the end of the channel through the injection pipe. The gasification agent of the invention directly acts on the coal seam of the section to be penetrated, thereby reducing the penetration time, shortening the furnace construction period, and achieving the effects of rapid furnace construction and rapid production.

Description

Underground coal seam penetration method

technical field

The invention relates to the technical field of underground coal gasification, in particular to an underground coal penetration method.

Background technique

Underground coal gasification technology mainly refers to the process in which solid fuels such as coal, coke or semi-coke react with gasification agents under high temperature, normal pressure or pressurized conditions, and are converted into gas products and a small amount of residue. The gasification agent is mainly water vapor, air, enriched oxygen of different concentrations or their mixture. Coal gasification process produces fuel gas, which can be used as industrial kiln gas or city gas, and can also be used to make mixed gas as raw material for synthetic ammonia, synthetic methanol and synthetic liquid fuel. Therefore, coal gasification technology is one of the important technologies of coal chemical industry .

In order to achieve large-scale production, gasification channels need to be prefabricated before underground coal gasification to build a gasifier. The coal seam water in the coal seam will seep into the burn-out area, this phenomenon is called liquid leakage. A large amount of liquid leakage is unfavorable to gasification operation. In the late stage of drilling tool construction, the coal seam in the channel and the burn-out interval is prone to landslide, which makes the drilling tool unable to continue working. Due to the limitation of construction technology level, it is impossible to completely connect the channel established by machinery with the area adjacent to the burn-out area, that is, the fire area. At the same time, considering the adverse effects of water in the coal seam and drilling fluid on gasification when the gasifier is built, the general situation Next, when there is fluid leakage during channel construction, that is, when there is drilling fluid leakage, the construction will be stopped, resulting in a section of coal seam blocking the channel between the channel established by the machine and the channel where the burnout area is located. In the process of coal seam gasification, the coal seam of this section must first be fractured by high-pressure gas to create channels, so that the two channels can be connected before gasification production can be carried out.

The existing way of connecting channels is to input gasification agent through the orifice and continuously increase the inlet pressure to fracture the coal seam. When a crack appears in the coal seam, the gas connects the two channels through the crack; because the gas enters through the crack The fire area, resulting in the formation of reverse ignition near the fire area, the channel is completely penetrated by the action of heat, and finally the pressure of the two channels is balanced. Although the above method realizes the penetration of the underground coal seam, the penetration time is long and the leakage rate is high. The main reasons are the following two points: (1) After the drilling is completed, the existence of coal seam water and drilling fluid makes most of the constructed channels full of water , the existing pressurization through the orifice, the gasification agent in the channel can reach the position to be penetrated after the water in the channel is drained under pressure, the longer the channel, the longer the drainage time, resulting in prolonged penetration time; (2) hole When the port is pressurized, the water in the coal seam will leak into the combustion void area during the pressurized drainage process. For the coal seam that has been drained of water, since the gasification agent is directly transmitted in the channel, it is easy to leak into the coal seam, thus prolonging the life of the coal seam. through time.

Contents of the invention

For this reason, the technical problem to be solved by the present invention is to overcome the problems in the prior art that it takes a long time to penetrate the coal seam, and the gasification agent is easy to leak in the coal seam, so as to provide a gasification agent that can directly act on the coal seam to be penetrated. And the underground coal seam penetration method with short penetration time.

In order to solve the above-mentioned technical problems, an underground coal seam penetration method according to the present invention is used to penetrate the coal seam between the prefabricated channel and the burnout zone during underground coal gasification, and the channel is formed by directional holes on the ground. The coal seam is extended and formed, and the end of the channel is close to the burn-out area. The method includes the following steps: Step S1: setting an injection pipe in the directional hole, injecting gas into the injection pipe to improve the flow rate of the channel. Slowly pressurize near the end; step S2: increase the pressurization amount of the injection pipe, observe the pressure change at the injection pipe, if the pressure starts to drop, it indicates that the gas in the injection pipe is leaking to the coal seam to be penetrated; step S3: Increase the air intake of the injection pipe to maintain the pressurization of the injection pipe; observe the pressure change value at the orifice of the directional hole, when the pressure value at the orifice approaches the When the pressure value of the empty zone is reached, the penetration is completed.

In one embodiment of the present invention, there is also a step of adjusting the pressure at the orifice of the directional hole to zero between the step S1 and the step S2.

In one embodiment of the present invention, the step of adjusting the pressure at the orifice of the directional hole to be zero is as follows: sealing the orifice of the directional hole, and slowly reducing the pressure of the orifice through a release pipe arranged below the sealing position. pressure until the pressure at the orifice is zero.

In one embodiment of the present invention, when the water in the release pipe is discharged to the ground, the pressure at the orifice is zero.

In one embodiment of the present invention, in the step S2, the amount of air entering the end of the channel is increased by increasing the pressurization amount of the injection pipe.

In one embodiment of the present invention, after the pressurization of the injection pipe is increased, a gap is formed between the passage and the coal seam to be penetrated, so that the gas in the injection pipe flows toward the coal seam to be penetrated. The leak causes the pressure in the injection pipe to begin to drop.

In one embodiment of the present invention, the maximum pressure of the pressurized volume of the injection pipe should be less than the pressure on the roof of the coal seam.

In one embodiment of the present invention, in the step S3, in order to maintain the pressurization amount of the injection pipe, the intake air volume of the injection pipe is gradually increased, and when the intake air volume rises to the set value, keep The intake air volume is constant, and the pressure change value at the orifice of the directional hole is observed.

In one embodiment of the invention, the end of the injection tube is near the end of the channel.

In one embodiment of the invention, the horizontal section of the channel is provided with supporting pipes.

The above technical solution of the present invention has the following advantages compared with the prior art:

The gasification agent of the invention directly acts on the coal seam of the section to be penetrated, thereby reducing the penetration time, shortening the furnace construction period, and achieving the effects of rapid furnace construction and rapid production.

Description of drawings

In order to make the content of the present invention more easily understood, the present invention will be described in further detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein

Fig. 1 is the structural representation of underground coal seam described in the present invention;

Fig. 2 is a schematic diagram of related equipment adopted on the ground by the present invention.

detailed description

As shown in Fig. 1 and Fig. 2, the present invention provides a kind of underground coal seam penetration method, is used for coal seam penetration between prefabricated channel 11 and burn-out zone 12 when underground coal is gasified, and described channel 11 is formed by the coal seam on the ground The directional hole 11A is extended and formed in the underground coal seam 10, the horizontal section of the passage 11 is located near the coal seam floor 10A, and the end 11B of the passage 11 is close to the burn-out area 12, and the method includes the following steps: S1: Install the injection pipe 13 in the directional hole 11A, and slowly pressurize the vicinity of the end 11B of the channel 11 by injecting gas into the injection pipe 13; Step S2: Increase the pressure of the injection pipe 13 amount, observe the pressure change at the injection pipe 13, if the pressure starts to drop, it indicates that the gas in the injection pipe 13 leaks to the coal seam to be penetrated; step S3: increase the intake air volume of the injection pipe 13 to maintain The pressurization amount of the injection pipe 13; observe the pressure change value at the orifice of the directional hole 11A, when the pressure value at the orifice approaches the pressure value of the burn-out zone 12, the penetration is completed.

The underground coal seam penetration method described in the present invention is used to penetrate the coal seam between the prefabricated channel 11 and the burn-out area 12 during underground coal gasification. Below the burn-out area 12 is ash 16, and the channel 11 It is formed by extending the directional hole 11A on the ground in the underground coal seam, the horizontal section of the channel 11 is located near the coal seam floor 10A, and the end 11B of the channel 11 is close to the burn-out area 12, in the step S1, An injection pipe 13 is arranged in the directional hole 11A, and the near end 11B of the passage 11 is slowly pressurized through the injection pipe 13, so that a certain pressure value is generated in the passage 11. When gas is injected into the coal seam, the gas can be directly transported to the coal seam to be penetrated, avoiding the possibility of gas leakage during the transmission process, thus improving the gas utilization rate and reducing the penetration time; in the step S2, increasing The pressurization amount of the injection pipe 13, with the continuous increase of the pressurization amount in the injection pipe 13, the gas in the injection pipe 13 will gradually leak to the coal seam to be penetrated, resulting in the pressure at the injection pipe 13. There is a downward trend in the pressure, and the pressurization amount in the injection pipe 13 can be inferred through the step S2 to effectively save energy; In step S2, the pressure has a downward trend, so it is necessary to increase the intake air volume of the injection pipe 13 to maintain the pressurized amount of the injection pipe 13, so that the gas in the injection pipe 13 continuously leaks to the coal seam to be penetrated , when the pressure value at the orifice of the directional hole 11A approaches the pressure value of the burn-out zone 12, it means that the coal seam to be penetrated between the passage 11 and the burn-out zone 12 has been completely opened , through to complete.

In the step S1 of the present invention, the intake pressure change is observed through the pressure gauge P1 provided on the injection pipe 13 on the ground, and the orifice pressure change is observed through the pressure gauge P2 provided at the orifice of the directional hole 11A. When slowly pressurizing near the end 11B of the channel 11 through the injection pipe 13, the pressurization process is carried out at a frequency of 0.5MPa/2h, and the maximum intake pressure is controlled between 2.5MPa and 3MPa.

Since the coal seam is in the gasification process, the channel 11 is generally longer and there is a certain amount of water in the channel 11, so the pressure value of the injection pipe 13 is different from the pressure value of the end 11B of the channel 11, In order to measure the pressure value at the end 11B, the pressure value at the orifice passing through the directional hole 11A can roughly reflect the pressure at the end 11B. In order to overcome the air and a certain amount of water present in the passage 11 Therefore, there is also a step of adjusting the pressure at the orifice of the directional hole 11A to zero between the step S1 and the step S2. Specifically, the step of adjusting the pressure at the orifice of the directional hole 11A to be zero is as follows: seal the orifice of the directional hole 11A, thereby preventing the pressure in the channel 11 from being disturbed by the external environment, by setting the pressure in the sealing position The relief pipe 14 below 11C slowly reduces the pressure at the orifice until the pressure at the orifice is zero.

In the above method of adjusting the pressure at the orifice of the directional hole, the pressure is slowly lowered through the release pipe 14 and repeated several times, and the pressure reduction rate is kept at 0.1MPa/h, so that the injection pipe 13 is fed into the air to ensure further The gas pressure is between 2.5MPa and 3MPa, so as to achieve the purpose of reducing the orifice pressure to zero. When water is discharged from the ground in the release pipe 14, it indicates that the air from the top of the water surface in the channel 11 to the orifice of the directional hole 11A is drawn out, and the valve 17 is closed at this time, and the pressure of the orifice drops to zero. When the construction continues, if the pressure change occurs again at the end 11B of the channel 11, the influence of the external environment can be directly eliminated, thereby avoiding the influence of the external environment on the end of the channel.

In the step S2 of the present invention, due to the pressurization of the injection pipe 13 in the step S1, the end 11B of the channel 11 already has a certain pressure, so that the coal seam to be penetrated is in the stage of self-drainage or the coal seam In the internal drainage stage, this stage is characterized by high pressure and low flow rate. In order to increase the pressurization amount of the injection pipe 13, it can be realized by increasing the pressurization amount of the injection pipe 13. In order to increase the intake air volume to 500Nm 3 /h, the intake air pressure is increased at a frequency of 0.5Nm ³ /4h, and when the intake air volume reaches 500Nm ³ /h by increasing the pressurization volume, the pressure is maintained. If the pressurization amount of the injection pipe 13 is gradually increased, a gap is gradually formed in the coal seam to be penetrated between the passage 11 and the burn-out area 12, and this gap can be a crack or a gap, and finally the injection The gas in the pipe 13 leaks to the coal seam to be penetrated through the gap, causing the pressure of the injection pipe 13 to gradually drop.

It should be pointed out that the maximum pressure of the injection pipe 13 pressurization amount should be less than the pressure on the coal seam roof 10B, so as to prevent the coal seam roof 10B from collapsing due to excessive pressure on the coal seam roof 10B. If the pressurization amount of the injection pipe 13 reaches the maximum, the intake air amount does not reach 500Nm ³ /h, and the pressure is maintained for operation. When the intake air volume reaches 500Nm ³ /h, after a period of time, the pressure at the injection pipe 13 begins to drop, indicating that a small amount of gas has entered the burn-out zone.

In order to further expand the gap of the coal seam to be penetrated so that the gas in the injection pipe 13 can continue to act on the coal seam to be penetrated, in step S3 of the present invention, it is necessary to maintain the pressurization amount of the injection pipe 13 , and in order to maintain the pressurized amount of the injection pipe 13, the intake air volume of the injection pipe 13 needs to be gradually increased. The operation is to maintain the pressure by increasing the intake air volume and continue to operate. When the intake air volume reaches 800Nm ³ /h, do not increase the intake air volume and keep the intake air volume unchanged. Observe the orifice of the directional hole 11A When the pressure change value at the orifice shows a downward trend and the pressure at the orifice approaches the pressure of the burn-out zone 12, it indicates that the pressure between the channel 11 and the burn-out zone 12 is When the through coal seam has been completely opened up, the through-through is completed.

The following is combined with specific data to illustrate how to realize the penetration of underground coal seams:

Embodiment one:

The injection pipe 13 is set in the directional hole 11A, the injection pipe 13 is lowered to a position 1 m away from the end 11B of the passage 11, and the injection pipe 13 is slowly moved toward the end 11B of the passage 11. Pressurize, slowly increase the intake pressure value to 2.0MPa, and observe the change of orifice pressure; when the orifice of the directional hole 11A has pressure, release the orifice through the release pipe 14 and slowly release the pressure to the orifice. , then close the valve 17 arranged at the release pipe 14; increase the pressurization of the injection pipe 13, and when the intake air reaches 300Nm ³ /h, stop the pressurization and observe the pressure at the injection pipe 13 If the pressure is lower than 3.0MPa, it indicates that the gas in the injection pipe 13 starts to leak into the coal seam to be penetrated. Increase the intake air volume of the injection pipe 13 to maintain the pressurized volume of the injection pipe 13, so that the intake air pressure is maintained at about 3.0MPa. By increasing the intake air volume several times, when the intake air volume reaches 600Nm ³ /h , stop increasing the intake air volume, keep the intake air volume through, and observe the pressure change value at the orifice of the directional hole 11A at the same time, when the air intake pressure value of the injection pipe 13 and the directional hole When the pressure value at the orifice of 11A drops to 0.7MPa, it indicates that the penetration is completed.

Embodiment two:

The injection pipe 13 is set in the directional hole 11A, and the injection pipe 13 is lowered to a position 0.5m away from the end 11B of the passage 11, and passes through the injection pipe 13 toward the vicinity of the end 11B of the passage 11. Pressurize slowly while controlling the valve 17 at the release pipe 14 to keep the inlet pressure of the injection pipe 13 within the range of 2.5MPa to 3.0MPa, so that the water in the channel 11 passes through the discharge pipe 14 discharge. When no more water is discharged in the release pipe 14, stop the orifice air intake, increase the pressurization of the injection pipe 13, observe the pressure change at the injection pipe 13, if the pressure begins to drop, it indicates that the The gas in the injection pipe 13 leaks to the coal seam to be penetrated, and at this moment, the air intake reaches 300Nm ³ /h, then the pressure at the injection pipe 13 is maintained, and the air intake of the injection pipe 13 is increased; The intake air volume of the injection pipe 13 is used to maintain the pressurized volume of the injection pipe 13. If the intake air volume is lower than 300Nm ³ /h, the pressure at the injection pipe is increased to increase the flow rate to 300Nm ³ /h h, under the condition of keeping the intake pressure constant, increase the intake air volume to 650Nm ³ /h, observe the pressure change value at the orifice of the directional hole 11A, when the orifice pressure drops below 0.7MPa, it means through Finish.

Regardless of Embodiment 1 or Embodiment 2, the distance between the end 11B of the channel and the burn-out area 12 of the present invention is the shortest in the coal seam section, thereby facilitating the penetration of the coal seam and making the penetration time the shortest. The injection pipe is driven forward and backward by ground machinery, and the injection pipe 13 can be a coiled tubing with mature technology.

In order to ensure the smooth progress of the penetration and avoid the problem that the coal seam 10 may collapse in the channel 11 and block the injection pipe 13 after the coal seam loses water, the end of the injection pipe 13 is arranged near the end 11B of the channel 11 . Specifically, the distance between the terminal position of the injection pipe 13 and the end 11B of the channel 11 is about 0.5m to 1.0m.

In order to overcome the leakage of drilling fluid and coal seam water in the channel to the burn-out area during the coal bed gasification process, the injection pipe 13 can be lowered in front of the channel, and the front end of the injection pipe 13 Sealing, in this way, can not only prevent the coal seam 10 from collapsing and blocking the injection pipe 13 after dehydration of the coal seam 10, but also prevent the coal slag deposited in the channel 11 from blocking the injection pipe 13. After the front end of the injection tube 13 is sealed, the seal can be broken by inputting a certain pressure into the injection tube 13 before use.

The horizontal section of the passage 11 is provided with a support pipe 15, and the payment pipe 15 can be supported by glass fiber reinforced plastics. The support pipe 15 mainly plays a role of supporting the horizontal section of the passage 11, thereby preventing The coal seam 10 collapsed and blocked the channel; at the same time, considering the steps of channel penetration and reverse gasification in the later stage, the support pipe 15 should have certain pressure resistance and flammability under high temperature conditions. Pressure-grade glass steel pipes. In actual construction, if the coal quality of the gasification coal field is relatively hard, the horizontal section of the channel 11 may not lower the support pipe 15 .

In the present invention, the passage 11 can be constructed in advance according to the plan, and when the measured fire area reaches the position to be penetrated by the passage 11, it will be pressurized and penetrated according to the method of the present invention; the vertical section and the inclined section of the passage 11 can also be constructed first. For the hole section, when the fire area burns to its vicinity, the horizontal section can be constructed. It can also be constructed after gasification for a period of time according to the actual situation.

The gas in the present invention refers to the gasification agent commonly used in the coal seam gasification process. The gasification agent can be selected from air or oxygen and other inert gases for proportioning, and the oxygen concentration is between 21% and 50%. In the second embodiment, the gasification agent is 35% carbon dioxide enriched with oxygen.

In summary, the underground coal seam penetration method of the present invention has the following advantages:

1. In the step S1 of the present invention, slowly pressurize the vicinity of the end of the passage through the injection pipe, so that a certain pressure value is generated in the passage, because when the gas is injected from the ground to the coal seam through the injection pipe, The gas can be directly transported to the coal seam to be penetrated, avoiding the possibility of gas leakage during the transmission process, thus increasing the utilization rate of the gas and reducing the penetration time; in the step S2, the injection pipe is increased The amount of pressurization, the gas in the injection pipe will gradually leak to the coal seam to be penetrated, resulting in a downward trend in the pressure at the injection pipe, through the step S2, the pressurization amount in the injection pipe can be inferred to effectively save Energy; in the step S3, in order to speed up the penetration of the coal seam between the passage and the burn-out area, it is necessary to increase the intake air volume of the injection pipe to maintain the pressurization of the injection pipe, so that the gas in the injection pipe is continuously flowing When the pressure value at the orifice of the directional hole approaches the pressure value of the burn-out area, it means that the coal seam to be penetrated between the channel and the burn-out area has It is completely opened up and completed.

2. In the coalbed gasification process of the present invention, since the pressure value of the injection pipe is different from the pressure value at the end of the passage, in order to measure the pressure value at the end, the pressure at the orifice through the directional hole The value can roughly reflect the pressure at the end, so there is also a step of adjusting the pressure at the orifice of the directional hole to zero between the step S1 and the step S2.

3. The end of the injection pipe in the present invention is arranged near the end of the passage, so as to avoid the problem that the coal seam may collapse in the passage after the coal seam loses water, thereby blocking the injection pipe.

4. In one embodiment of the present invention, when the injection pipe is ventilated, when pressure appears at the orifice of the directional hole, the orifice is released through the release pipe to slowly release the pressure to the orifice, so that the The pressure at the orifice drops to zero, and the gasification agent can directly act on the part to be penetrated, which is beneficial to reduce the penetration time and improve the penetration efficiency.

Apparently, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. However, the obvious changes or changes derived therefrom are still within the scope of protection of the present invention.

Claims (10)

1. a kind of subterranean coal penetrates method, during for by underground coal gasification(UCG) between prefabricated passage (11) and burned out area (12) Coal seam insertion, the passage (11) formed by the directional hole (11A) on ground in subterranean coal (10) extension, and the passage (11) end (11B) is close to the burned out area (12), it is characterised in that methods described comprises the following steps：

Step S1：Ascending pipe (13) is set in the directional hole (11A), passes through the injection gas pair into the ascending pipe (13) The end (11B) of the passage is nearby slowly pressurizeed, and the end of the terminal location of the ascending pipe (13) and the passage The distance at end (11B) is in 0.5m between 1.0m；

Step S2：The amount of pressurization of the ascending pipe (13) is improved, the pressure change at the ascending pipe (13) place is observed, if pressure is opened Begin to decline, show gas in the ascending pipe (13) to coal seam seepage to be penetrated；

Step S3：Increase the air inflow of the ascending pipe (13) to maintain the amount of pressurization of the ascending pipe (13)；Described in observation Change value of pressure at the aperture of directional hole (11A), the pressure value at aperture level off to the pressure values of the burned out area (12) When, insertion is completed.

2. subterranean coal according to claim 1 penetrates method, it is characterised in that：The step S1 and step S2 it Between be additionally provided with the step of pressure is zero at the aperture for adjusting the directional hole (11A).

3. subterranean coal according to claim 2 penetrates method, it is characterised in that：The hole of the regulation directional hole (11A) The step of pressure is zero at mouthful is as follows：The directional hole (11A) aperture is sealed, by being arranged on below sealing station (11C) Exhaust stack (14) slowly reduce the aperture pressure until aperture at pressure be zero.

4. subterranean coal according to claim 3 penetrates method, it is characterised in that：There is water discharge in the exhaust stack (14) During ground, the pressure in the aperture is zero.

5. subterranean coal according to claim 1 penetrates method, it is characterised in that：In the step S2, by improving State the amount of pressurization of ascending pipe (13) and be passed through channel end (11B) air inflow to increase.

6. subterranean coal according to claim 5 penetrates method, it is characterised in that：The amount of pressurization of the ascending pipe (13) carries Gao Hou, the coal seam to be penetrated between the passage (11) and the burned out area (12) forms gap, so that the ascending pipe (13) gas in causes the pressure of the ascending pipe (13) to begin to decline to coal seam seepage to be penetrated.

7. subterranean coal according to claim 6 penetrates method, it is characterised in that：Ascending pipe (13) amount of pressurization is most High pressure should be less than the pressure that roof (10B) is born.

8. subterranean coal according to claim 1 penetrates method, it is characterised in that：In the step S3, in order to maintain The amount of pressurization of ascending pipe (13) is stated, the air inflow of the ascending pipe (13) gradually increases, and after air inflow is increased to setting value, protects Hold that the air inflow is constant, observe the change value of pressure at the directional hole (11A) aperture.

9. the subterranean coal insertion method according to any one in claim 1 or 5-8, it is characterised in that：The injection The end of (13) is managed near the end of the passage (11) (11B).

10. subterranean coal according to claim 1 penetrates method, it is characterised in that：The horizontal segment of the passage (11) is set There is supporting tubing (15).