RU2251000C1 - Method for complex extraction of coal bed - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: method includes drilling a system of hydraulically connected wells, directed and horizontal, cased and not cased along coal bed. Hydrodynamic and fire effect on coal bed is performed through these. Gassing and degassing processes for coal bed are performed serially via a system of hydraulically connected wells. In that case degassing process is performed by thermal treatment of channels of coal by counter-flow displacement of burning source after combustion of coal bed in one of wells. Then neutral gas is forced into system of hydraulically connected wells, ignited zone is quenched and coal methane is extracted from several wells, equipped for degassing. Gassing process is performed via repeated combustion through specially drilled vertical well and forcing flow into directed cased wells. Formed combustible gas is drained through directed non-cased wells in direction by normal lines from horizontal transverse well.

EFFECT: higher efficiency.

1 dwg

Description

The invention relates to the problem of using coal in natural conditions of its occurrence with obtaining gaseous energy carriers.

Known shaftless method of underground coal gasification using wells drilled from the surface / 1 /. The use of this method for the degassing of a coal seam cannot be implemented.

There is also known a technical solution for mine degassing of coal deposits using wells drilled from the surface and from mine workings / 2 /. Such a solution to the problem, firstly, provides the degree of extraction of coal methane by only 20-25%, and secondly, provides for the subsequent less dangerous extraction of coal and does not allow coal gasification without drilling additional wells.

The closest in technical essence and the achieved result is a method of intensifying methane recovery of a coal seam by preliminary firing of horizontal drilling channels / 3 /. However, this decision does not provide for the possibility of combining the processes of degassing and gasification of a coal seam. The technological regulations that ensure the consistent implementation of degassing and underground gasification processes in a single system of hydraulically connected wells have not been worked out.

The aim of the invention is the integrated development of a coal seam by combining the processes of degassing and gasification through a system of the same wells.

This goal is achieved by the fact that in the method of integrated development of a coal seam, which consists in drilling a system of hydraulically coupled wells, directed and horizontal, cased and uncased in a coal seam, performing hydrodynamic and fire effects on the coal seam through them, the processes of degassing and gasification of the coal seam are carried out sequentially by means of a system of hydraulically connected wells, igniting a coal seam in one of the wells, heat treatment of drilling channels about coal by countercurrent movement of the combustion zone, injection of neutral gas into the system of hydraulically connected wells and quenching of the inflamed zone, extraction of coal methane from several wells equipped for degassing, and at the end of the degassing process, the coal seam gasification is carried out by re-ignition through a specially drilled vertical well, injection of blast into directional cased wells and removal of the resulting combustible gas through directional uncased wells in The direction along the normal from the horizontal transverse borehole.

A comparative analysis of the proposed solution with the prototype shows that the proposed method is distinguished by specific proposals for drilling a special system of directional and horizontal wells, as well as detailed technological regulations aimed at the sequential implementation of the processes of degassing and gasification of a coal seam, which meets the criterion of “novelty”.

Analysis of the claims showed that the claimed invention meets the criterion of "significant differences".

The proposed method is illustrated in the drawing, which shows a system of directional and horizontal wells in the plane of the coal seam, which allows for the sequential degassing and gasification of coal in the natural environment of its occurrence. Directional wells 1 are cased to the full length, directional wells 2 are cased by the column only until the well path enters the coal seam, a horizontal transverse well 3, passed through coal without casing, an additional vertical well 4 connected to the well path 3.

The method of integrated development of a coal seam is implemented as follows.

Directional wells 1, cased to the full length, and directional wells 2, cased by a column only before the well path enters the coal seam, are drilled on a coal seam. Directional wells 1 and 2 alternate with each other.

Directional wells 1 and 2 are connected using a horizontal transverse well 3, passed through coal without casing. All wells are connected in a hydraulically coupled system. Such a well system makes it possible to first degass a coal seam and then gasify it (gas out).

To increase the efficiency of the first stage of the degassing process, the drilling channels of wells 2 and 3 are thermally expanded, for which a coal seam is fired at the horizon of well 3, air blast is injected into well 3 and well 2. The combustion center moves towards the injected air blast, leaving behind thermally developed reservoirs with a diameter of 0.5-0.75 m (the diameter of the drilling channels 0.15-0.2 m).

After quenching with a neutral gas, such as nitrogen, the developed drilling channels are artificial reservoirs with increased drainage ability, which allows us to proceed to the stage of draining this section of the coal seam, and then to the extraction of coal (desorbed) methane. Due to the high drainage ability of the created reservoirs, the processes of drainage and degassing of the coal seam are carried out intensively, with a high degree of energy extraction.

At the end of the degassing process, after a drop in the methane production rate, they begin the second stage of the process - underground coal gasification. To do this, drill an additional vertical well 4 in the immediate vicinity of the path of the well 3, re-ignite the coal seam in the bottom of the well 4 and connect it to the path of the horizontal transverse well 3.

The blast is injected into wells 1, and the resulting combustible gas is discharged through wells 2. Gasification of the coal seam occurs normal to the horizontal transverse well 3. The process of gasification of coal continues until the coal seam is completely degassed, the reserves of which are limited by the extreme directional wells 2 and the horizontal transverse well 3.

The problem of implementing integrated development of a coal seam by combining technological processes is currently of great interest in countries with an industrially developed method for the extraction of coal methane (USA, China, Austria).

The claimed invention, aimed at solving the problem of sequentially conducted degassing and underground gasification processes in a system of hydraulically coupled wells, will allow to obtain a high economic effect by reducing the cost of recoverable energy.

Sources of information

1. Kreinin E.V. Coal as a source of substitute for natural gas // Coal, 2001, No. 7, p.17, Fig. 2.

2. Guidelines for the degassing of coal mines. - M .: 1990, p.186.

3. Patent No. 2209984, 2003-11-24 (prototype).

Claims (1)

The method of integrated development of a coal seam, which consists in drilling a system of hydraulically connected wells, horizontal transverse and directed, cased and uncased in a coal seam, through which hydrodynamic and fire effects are applied to the coal seam, characterized in that the processes of degassing and gasification of the coal seam are carried out sequentially by systems of hydraulically coupled wells, ignition of a coal seam in one of the wells, heat treatment of drilling channels for coal by the otiochnical movement of the combustion zone, injection of neutral gas into the system of hydraulically connected wells and quenching of the ignited zone, extraction of coal methane from several wells equipped for degassing, and at the end of the degassing process, the coal seam gasification is carried out by re-ignition through an additional drilled vertical well, blowing into directional cased wells and removal of the resulting combustible gas through directional open-hole wells in lenii along the normal from the horizontal transverse borehole.