RU2293185C2 - Method for increasing gas yield of coal-methane formation - Google Patents

Abstract

FIELD: technologies for extracting methane contained in coal and rocks.

SUBSTANCE: invention includes drilling inclined and horizontal channels, expanding them, and also usage for drying deposit and following extraction of coal methane. Method is special because after completion of channel drilling, face part of drilling tool is equipped with high pressure tip, through the tip liquid is forced under high pressure, channel walls are processed with high pressure liquid jet, drilling tool with the tip is extracted in stages, and hard components transported in flow of liquid are separated from liquid on the surface and utilized.

EFFECT: creation of universal method for expanding drilling channels in coal and rocks, usage of which guarantees increased methane yield of coal-gas deposit.

3 cl, 1 dwg

Description

The invention relates to a newly created coal-gas sub-industry, the main task of which is to extract methane contained in coal and rocks of coal deposits.

A known method of degassing (methane extraction) of a coal seam using wells drilled both from mine workings and from the surface [1]. The diameter of such wells does not exceed 100 mm; the small surfaces of such drilling channels cause small inflows of coal methane to them. Moreover, the inclusion of these channels in a vacuum-suction mine ventilation system leads to a large dilution of the suction methane (the methane content in the methane-air mixture ranges from 5 to 20%), which makes it difficult to use it as a fuel.

Another well-known technical solution was the drilling of an inclined well in the soil of a coal seam in the Donbass [2]. Fractures with a coal seam for its degassing were carried out along the length of this well. However, the small surfaces of the created hydraulic fracturing slots limited their draining abilities; the methane production rates were small.

The closest technical solution is the method of firing a horizontal drilling channel [3]. However, a significant drawback of this solution is the expansion of the drilling channel by moving along the combustion site. This method significantly limits its use. On the one hand, it is far from always permissible to have a burning center in the mine degassing system (according to safety regulations). On the other hand, the fire expansion of the drilling channel, passed in the soil and roof of the coal seam, is generally impossible. This disadvantage of the known technical solution severely limits its widespread use.

The aim of the present invention is to provide a universal method for expanding drilling channels in coal and rocks, the use of which would guarantee an increase in methane recovery of a coal-gas field.

This goal is achieved by the fact that in the known method of degassing coal seams, which consists in drilling inclined and horizontal channels, expanding, and also using them for subsequent drainage of the array and extraction of coal methane, they equip the downhole part of the drilling tool with a special high-pressure nozzle after completion of drilling, pump it through fluid under high pressure and thereby destroy the walls of the channel, gradually (stepwise) removing the drilling tool with a nozzle, expand the drilling channel throughout its length, and the solid particles transported in the fluid stream are separated on the surface and disposed of. In addition, as a high-pressure working fluid, not only water, but also more viscous fluids are used, and the drilling channels pass not only in the coal seam, but in its soil and roof, thereby working and working out (unloading) the coal seam, and use them for the extraction of methane from a gas and gas field. For greater coverage of the latter, drilling channels are placed in various combinations, mainly parallel to each other, and the distances between them are performed taking into account the methane content of the field (specific gravity - m ³ / sq. Km; specific methane content - m ³ / t).

A comparative analysis of the claimed invention with the prototype shows that the claimed technical solution is characterized in that the expansion of the drilling channels is carried out by a high-pressure jet of fluid along their entire length. At the same time, expandable drilling channels are used not only in the coal seam, but also in the soil and roof, and for greater coverage of the gas and gas field, the drilling channels are placed parallel to each other with distances between themselves, due to the methane content of the field. These differences meet the criterion of "novelty" for the claimed invention.

In addition, it according to the inventive step can be characterized by the criterion of "significant differences", since the inventive method has the versatility and the ability to be implemented not only in the coal seam, but also the rocks containing it.

The drawing shows a schematic diagram of the implementation of the proposed method in a coal seam.

The proposed method for increasing gas recovery is implemented on a coal-methane deposit as follows.

A vertical-horizontal well 1 is cased before entering the coal seam, and a drilling channel 2 with a diameter of 150-200 mm passes through the coal seam. After drilling is completed to the design elevation, the drilling tool 3 is removed to the surface and equipped (at the end) with a special nozzle 4 for supplying a high-speed jet of working fluid to the walls of the drilling channel 2. The hydropercussion effect of the liquid on the walls of the drilling channel 2 is accompanied by the destruction and breaking off of solid particles from the surface of the channel. In the reverse flow of the working fluid flowing between the drilling tool 3 and the walls of the drilling channel 2 or the casing of the well string 1, the breakaway solid particles are carried to the surface. On the surface carry out (one of the known methods) the separation of solid particles from liquid. Based on environmental considerations, the liquid and solid fraction are disposed of in the surface complex. Gradually removing the tool 3, mechanically process the drilling channel 2 along its entire length to the end of the casing 1.

Similar vertically horizontal wells pass in the soil and roof of a coal seam (not shown). After water treatment of their open-hole drilling channels, drains with a developed lateral surface are obtained, which contributes to an increase in the flow of methane from a gas and gas field to them. In addition, these pedigree expanded channels are used for unloading the coal seam (part-time and part-time work).

Hydraulically treated drilling channels in the coal seam and the rocks surrounding it are reliable high-yield drains both at the stage of drainage of the field and at the main stage - production of coal methane.

The choice of the type of working fluid, as well as the hydraulic parameters of its outflow through nozzles 4, is determined based on the strength characteristics of destructible solid surfaces and the lifting force of transport of solid particles to the surface.

For greater coverage of a coal-gas field with coal methane extraction technology, hydraulically treated drilling channels can be located in various combinations. The most optimal is their parallel arrangement.

Depending on the angle of incidence of the coal seam and coal methane production technology, the drilling channels 2 can be not only horizontal, but also inclined. The technique of their hydraulic expansion remains the same (discussed above).

The claimed invention is planned to be implemented at the experimental site of Promgaz OJSC in the South Kuzbass. The expected production rates of coal methane per drilling channel are 100,000 m ³ / day, which will ensure the profitability of the coal and methane field.

Information sources

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

2. Yarunin S.A. Experience in conducting hydrodynamic effects on a coal mass through a well with horizontal completion. M .: Coal, 1990, No. 6, p. 18-20.

3. Patent No. 2209984, 7 E 21 F 7/00, 2003.

Claims (3)

1. A method of increasing the gas recovery of a coal-methane field, which consists in drilling inclined and horizontal channels, expanding them, and also using coal methane to drain the coal-field and subsequent extraction of carbon methane, while the drilling channels are placed parallel to each other, after they have been drilled from open-hole drilling channels, high-yield drains with a developed lateral surface, which are used at the stage of drainage of the field, for drainage of coal methane and for unloading coal about the reservoir, carried out by its underworking and underworking by drilling channels, which pass not only in the coal seam, but also in its soil and roof, and receive drains with a developed lateral surface by equipping the downhole part of the drilling tool with a high-pressure nozzle, injection through the high-pressure nozzle of the working fluid under high pressure and treatment of the wall of the drilling channel with a high-pressure, high-speed jet of working fluid, which provides a hydraulic impact on the walls of the drilling channel, accompanied by breaking and breaking off solid particles from the surface of the drilling channel, while gradually removing the drilling tool with a high-pressure nozzle in steps, hydraulically treat the drilling channel along its entire length to the end of the well casing, and the breakaway solid particles transported in the return flow of the working fluid are separated from the liquid on the surface and disposed of. 2. A method of increasing the gas recovery of a coal-methane deposit according to claim 1, characterized in that not only water, but also more viscous solutions are used as the working fluid. 3. The method of increasing gas recovery of a coal-methane deposit according to claim 1, characterized in that the distances between the drilling channels are determined taking into account the methane content of the field — specific gravity and specific methane content.