METHOD FOR FLUID CARRIAGE IN DEEP-SEAM COAL HYDRAULIC MINING

Abstract

The present invention relates to a method for fluid carriage in deep-seam coal hydraulic mining, aimed at the mining of coal seams buried underground at depths of 500 metres to below several thousands of metres. By means of methods such as well drilling and tubular columns, hydraulic power is conveyed to the coal seam excavation using tubular columns, to erode and cut coal buried underground, and by circulating fluid at a certain flow rate, cut coal is carried to the surface, achieving unmanned excavation in the shaft. The present method is an integrated coal exploitation technique achieving synchronous mining of coal field gas and solids, and is suitable for coal seams where conventional methods are unable to mine or mining is not economically viable, while also being suitable for establishing gasification channels for underground coal gasification.

Description

TECHNICAL FIELD

Embodiment of the present invention relates to a novel process for hydraulic mining and fluid carrying of deep-seam coal, mainly aiming at mining of coal seams buried in the ground under 500 meters to thousands of meters of depth.

BACKGROUND

It is in developing that by processes such as well drilling, tubular columns and the like, coal deeply buried in the ground is washed and cut, and the cut coal is brought out of the ground through the circulation of fluid. The tubular columns are utilized to transmit hydraulic power to the coal seams for tunneling and then transmit coal to the ground through fluid, realizing downhole unmanned tunneling.

SUMMARY

The novel process is a coal development technology for realizing the integration of synchronous mining of gas and solid of coal fields, is especially suitable for the coal seams which can not be mined with a conventional method or are uneconomically mined, and is suitable for establishment of gasification tunnels of underground gasification of coal.

To overcome the deficiencies of the prior art, embodiment of the present invention provides a novel process for hydraulic mining and fluid carrying of deep-seam coal, particularly a method for hydraulic mining and fluid carrying of coal seams buried in the ground with a depth under one thousand meters. The process includes:

1. an overall development scheme in resource area is drawn up according to the amount of resources from coal resource exploration and the actual situation of the geological formation;

2. the simultaneous development of a same layer of a single well or multiple wells is implemented according to the overall scheme;

3. the development of several sets of coal seams is required to follow a principle of development from a deeper seam coal seam to a less deeper coal seam;

4. the pressure coefficient of coal seams needs to be greater than 0.9 to ensure the economical implementation of the development scheme;

5. a well drilling process is utilized to establish a production well, that is, after drilling to the top of the deepest coal seam by utilizing the well drilling process, a casing is put down for well cementation, and then a cement plug is drilled to open the coal seams;

6. a directional drilling process is utilized, a specific hydraulic cutting drill and specific double-layer tubular columns are used, fluid with a certain performance is prepared, and production is performed by a ground mud pump;

• • 1) a directional drilling process is utilized, and a downhole television set, a position finder and a direction instrument are used to ensure the quality of tunneling;
  • 2) for a specific hydraulic cutting drill, hydraulic cutting drills of different parameters are customized according to thicknesses and dip angles of the coal seams, and the parameters mainly include rotation speed, the diameter of nozzles, and the jet angle of nozzles;
  • 3) for specific double-layer tubular columns, tubular columns of different diameters are utilized according to capacity;
  • 4) the performance of the fluid is configured according to the pressure coefficient and density of coal seams, and the main performance indexes include density, viscosity and cutting force; the fluid (also called coal alkali liquor) is mainly prepared from water, bentonite, caustic soda (sodium hydroxide), coal powder and gangue powder;
  • 5) the main parameters of a mud pump include pressure (generally high pressure, which is greater than 10 MPa) and displacement;

7. mixture of coal briquettes and coal gas (CH4) is brought out of the ground through fluid with a certain flow velocity and then enters a processing system on the ground;

• • 1) the mixture of mud, coal and gas enters a three-phase separation system first so that the mud, coal and gas are separated simultaneously;
  • 2) the coal gas (CH4) enters a gas processing station, is then compressed and transmitted to users;
  • 3) the coal briquettes enter a coal washing workshop and are then processed into cleaned coal, which is transferred to a cleaned coal warehouse for sale; ash and gangue from the coal washing workshop enter a gangue grinding plant and are then processed into materials below 200 meshes for preparing mud; and waste water from the coal washing workshop is transferred to a mud preparation plant and used for preparing mud; and
  • 4) the mud flows into a sedimentation tank from the three-phase separator for settling powdered coal and fine sand particles; and the sediment is transferred to the coal washing workshop for processing, and the mud is recycled to a circulation pool for recycling.

According to the development scheme, a multi-well and multilayer well pattern is implemented so as to perform the underground hydraulic mining of coal.

For a mining area having multiple coal seams, it is preferred to mine bottom coal seams and then upper coal seams successively.

Embodiments of the present invention has the following advantages:

1. the synchronous mining of gas and solid of a coal field is realized, and the utilization ratio of resources is high; the recovery ratio of coal may be 80% and above; the gas is completely recycled;

2. downhole unmanned and hydraulic operations are realized, so as to avoid production accidents such as gas explosion, collapse and the like during conventional coal mining;

3. this novel process is more advantageous in terms of environmental protection than the conventional coal mining, is free of damages to the ambient environment, and has small occupation of production land, no sewage discharge, no waste, gangue and dust; and, the coal gas is fully recycled;

4. stock resources in various places may be fully utilized, thereby avoiding the long-distance transportation of coal and reducing the energy consumption;

5. less investment in construction, short cycle and high production efficiency are realized; and

6. vigorous exploration and development of deep resources, mainly coking coal, may significantly make up the resource shortage and has good benefit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of flow of a process according to an embodiment of the present invention.

Reference numerals and corresponding explanation FIG. 1 are listed as below:

1  Electricity transformer
   and distributor
2  Power distribution
   cabinet
3  Fluid circulating pump
4  Well winch
5  Derrick
6  Three-phase separator
7  Natural gas processing station
8  Separated liquid phase
9  Separated coal
10 Sedimentation tank
11 Sediment processing device
12 Fluid
13 Specific hydraulic mining
   drill
14 Inner tubular column
15 Outer tubular column
16 Casing
17 Coal seams

FIG. 2 is a planar graph of flow of the process according to an embodiment of the present invention.

Reference numerals and corresponding explanation in FIG. 2 are listed as below:

1  Electricity transformer
   and distributor
2  Pump
3  Mud circulating pool
4  Wellhead
5  Three-phase separator
6  Natural gas processing station
7  Users
8  Sedimentation tank
9  Sediment processing device
10 Separated liquid phase
11 Separated coal
12 Coal washing workshop
13 Cleaned coal warehouse

DETAILED DESCRIPTION

The specific embodiments of the present invention will be further described hereinafter with reference to the accompanying drawings.

Referring to FIG. 1, according to the well drilling process of an embodiment of the present invention, a system which includes an electricity transformer and distributor (1), a power distribution cabinet (2), a mud circulating pump (3), a well winch (4) and a derrick (5) is utilized to perform drilling to the top of the deepest coal seam, a casing (16) is put down for well cementation, and then a cement plug is drilled to open the coal seams (17). The pressure coefficient of coal seams is required to be greater than 0.9 to ensure the economical implementation of the development scheme.

Referring to FIG. 1, a directional drilling process according to an embodiment of the present invention is utilized, the prepared fluid (12) with certain performance transmits hydraulic power to the coal seams for tunneling by a ground mud pump (3) via a specific double-layer tubular column (i.e., an inner tubular column (14) and an outer tubular column (15)), and the coal deeply buried in the ground is washed and cut by using a specific hydraulic cutting drill (13). The coal mixture is brought out of the ground through fluid with a certain flow velocity and then enters a ground processing system.

Referring to FIG. 1, the parameters of the mud pump (3) in an embodiment of the present invention mainly include pressure and displacement. The pressure is required to be a high pressure, generally greater than 10 MPa.

Referring to FIG. 1, for the specific double-layer tubular columns in an embodiment of the present invention, i.e., the inner tubular column (14) and an outer tubular column (15), the tubular columns (14, 15) of different diameters are utilized according to production capacity. The performance of the fluid (12) in an embodiment of the present invention is configured according to the pressure coefficient and density of coal seams, and the main performance indexes include density, viscosity and cutting force.

Referring to FIG. 1, for a specific hydraulic cutting drill (13) in an embodiment of the present invention, hydraulic cutting drills (13) of different parameters are customized according to thicknesses and dip angles of the coal seams (17), and the main parameters include rotation speed, the diameter of nozzles, and the jet angle of nozzles.

Referring to FIG. 1, the fluid (12) (also called coal alkali liquor) in an embodiment of the present invention is mainly prepared from water, bentonite, caustic soda (sodium hydroxide), coal powder and gangue powder.

Referring to FIG. 2, a planar graph of flow of the process is shown, including an electricity transformer and distributor (1), a pump (2), a mud circulating pool (3) and a wellhead (4). The coal mixture in an embodiment of the present invention enters a three-phase separation system (5) first so that the mud (10), coal (11) and gas (7) of three phases are separated, respectively.

Referring to FIG. 2, the coal gas (CH4) in an embodiment of the present invention enters a gas processing station (6), is then compressed and transmitted to users.

Referring to FIG. 2, coal briquettes (11) in an embodiment of the present invention enter a coal washing workshop (12) and are then processed into cleaned coal, and the cleaned coal is transferred a cleaned coal warehouse (13) for marketing.

Referring to FIG. 2, the mud (10) in an embodiment of the present invention flows into a sedimentation tank (8) after separation, powdered coal and fine sand particles are settled by a sediment processing device (9), the sediment is transferred to the coal washing workshop (12) for processing, and the mud is recycled to a circulation pool (3) for recycling.

Claims

1-10. (canceled)

11. A method for hydraulic mining and fluid carrying of deep-seam coal, for realizing a coal development with integration of synchronous mining of gas and solid of coal fields, for the coal seams which cannot be mined with a conventional method or are uneconomically mined, and for the establishment of gasification tunnels of underground gasification of coal, wherein the method includes:

by a directional drilling process, using a hydraulic cutting drill and double-layer tubular columns, preparing and using fluid with a certain performance as a carrier, and bringing mixture of underground deep-seam coal out of the ground through the fluid with a flow velocity;

simultaneously separating mud, coal and gas in the mixture by a three-phase separator system; and

coal gas being fed into a gas processing station, then being compressed and transmitted to users;

coal briquettes entering a coal washing workshop and being processed into cleaned coal, which is then transferred to a cleaned coal warehouse for subsequent sale; and

the mud being recycled to a circulation pool for recycling.

12. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 11, wherein an overall development scheme is drawn up according to the amount of resources from coal resource exploration and the actual situation of the geological formation, and the simultaneous development of a same layer of a single well or multiple wells is implemented according to the overall scheme.

13. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 11, wherein, several sets of coal seams is developed from deep coal seam to shallow coal seam, and pressure coefficient of coal seams is greater than 0.9.

14. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 12, wherein, several sets of coal seams is developed from deep coal seam to shallow coal seam, and pressure coefficient of coal seams is greater than 0.9.

15. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 11, wherein the well drilling process is utilized to establish a production well; after drilling to the top of the deepest coal seam by the well drilling process, a casing is put down for well cementation, and then a cement plug is drilled to open the coal seams.

16. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 11, wherein the directional drilling process is utilized, a specific hydraulic cutting drill and specific double-layer tubular columns are utilized, fluid with a certain performance is prepared, and finally production is performed by a ground surface mud pump.

17. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 13, wherein the directional drilling process is utilized, a specific hydraulic cutting drill and specific double-layer tubular columns are utilized, fluid with a certain performance is prepared, and finally production is performed by a ground surface mud pump.

18. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 15, wherein the directional drilling process is utilized, and a downhole television set, a position finder and a direction instrument are used to ensure the quality of tunneling.

19. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 16, wherein, hydraulic cutting drills of different parameters are customized according to thicknesses and dip angles of the coal seams, and the parameters include rotation speed, the diameter of nozzles, and the jet angle of nozzles.

20. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 16, wherein, the double-layer tubular columns of different diameters are utilized according to production capacity, the performance of the fluid is configured according to the pressure coefficient and density of coal seams, and indexes of the performance include density, viscosity and cutting force; the fluid is prepared from water, bentonite, caustic soda, coal powder and gangue powder; and parameters of the mud pump include pressure and displacement.

21. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 11, wherein the mixture of coal briquettes and coal gas is brought out of the ground through fluid with a certain flow velocity and then enters a processing system on the ground.

22. The method for hydraulic mining and fluid carrying of deep-seam coal according to claim 21, wherein the mixture of the fluid enters a three-phase separation system first so that the mud, coal and gas are separated simultaneously; the coal gas enters a gas processing station, is then compressed and transmitted to users; the coal briquettes enter a coal washing workshop and are then processed into cleaned coal, and the cleaned coal is transferred a cleaned coal warehouse for subsequent sale; ash and gangue from the coal washing workshop enter a gangue grinding plant and are then processed into materials below 200 meshes for preparing mud; waste water from the coal washing workshop is transferred to a mud preparation plant and used for preparing mud; the mud flows into a sedimentation tank from the three-phase separator for settling powdered coal and fine sand particles; and the sediment is transferred to the coal washing workshop for processing, and the mud is recycled to a circulation pool for recycling.