RU2453705C1 - Method for degassing of coal beds - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method consists in guiding the deviated horizontal/vertically horizontal wells from the ground surface with output of their downhole part to horizontal plane, provision the wells with pipe casing, connection to the vacuum pump and methane recovery from unworked coal. On the mine field a series of above-ground wells are guided with output of their horizontal portions into the working and superimposed coal seams. In addition to the above-ground wells, the short isolated from mine weather underground wells are designed and equipped, by means of those the hydraulic connection between above-ground well and underground ones is made with the capability of borehole fluid discharge. In preparation of excavation site for upwall development, the horizontal portion of above-ground well is guided along the axis of excavation site, and in preparation of excavation site for along-strike development - arriswise the lengthwise extended section of degassed reservoir, with minus angle of elevation of horizontal well portion. In the expanded excavation site a counter on-shore well is guided with placing its horizontal portion in the tapped coal seam.

EFFECT: gain in performance of gas drainage from the working and superimposed seams.

4 cl, 2 dwg

Description

The invention relates to mining and can be used to extract methane from a formation of coal seams in underground mining in order to reduce the methane abundance of mining sites (fields) without laying underground degassing pipelines.

There is a method of degassing coal seams that are closely aligned in a suite with wells drilled from the development of a coal seam being developed through roof rocks with the bottomhole part of the well being brought into the plane of degassed coal seams [1].

The essence of this method of degassing is to extract methane from adjacent seams only under the conditions of cleaning operations and unloading coal seams from rock pressure, which is its drawback, since the duration of underground wells is short-term, especially at high speeds of moving lavas.

There is a method of degassing coal seams based on their hydraulic separation through vertical wells drilled from the earth's surface. The essence of it is to conduct a vertical well, casing it, sealing the annulus, injecting fluid into the coal seam under pressure and at the expense of providing the disclosure of the natural fracture system in the coal seam, pumping out the liquid and extracting the coal gases [2].

The disadvantages of this method include the uneven treatment of coal seams through the borehole over the area due to the disclosure of 2-3 main crack systems oriented mainly in one direction, the duration of fluid pumping and the low efficiency of preliminary degassing of coal seams before the start of treatment work, contributing to the unloading of the rock mass and its drainage from the working fluid.

The closest in technical essence and the achievement of the goal to reduce methane emissions from coal seams is a method of degassing adjacent seams and worked out space, including drilling vertically horizontal curved wells from the earth's surface with the horizontal part under the first coal seam from the developed seam [3] .

The disadvantages of this method include the short duration of the wells, and only in the zone of influence of the working face. In addition, the location of the horizontal part of the well under the adjoining formation reduces its effectiveness and the concentration of methane in the captured mixture.

The aim of the invention is to increase the efficiency of sequentially preliminary degassing of the coal seam suite, including the developed seam, and their current degassing in the zone of influence of the working face, elimination of the underground degassing pipeline network by arranging the horizontal part of the wells in the plane of the coal being developed and adjoining, creating a hydraulic connection between surface wells (their horizontal part) and underground wells equipped with downhole drainage devices fluids from surface wells drilled both in the plane of the developed seam and in the plane of the adjacent coal seams.

This goal is solved by the fact that in the method of degassing coal mines, which includes conducting inclined horizontal / vertical-horizontal wells from the earth’s surface with the bottom being brought out to the horizontal plane, equipping the wells with casing pipes, connecting them to a vacuum pump and extracting methane from the carbonaceous massif conducting on the mine field a series of surface wells in excavation sections being prepared for mining with the withdrawal of horizontal parts of the well into the coal in the developed and adjacent formations, additional to the surface wells conducting and equipment in the excavation sections of short underground wells isolated from the mine atmosphere, with the help of which, prior to the start of the treatment work, they create a hydraulic connection between the surface and underground wells with the possibility of draining the borehole fluid, conducting horizontal parts of the surface well along the axis of the excavation section during preparation excavation site for mining by lava uprising, and in the preparation of the excavation site for mining lava along strike - conducting the horizontal part of the well diagonally extended along the length of the section of the degassed formation with a negative elevation angle; additional to the surface well, conducting an oncoming surface well with placing its horizontal part in the produced coal bed with orientation in the direction of the mounting chamber, holding short wells in the plane of the developed formation, rising and oriented to the horizontal part of the surface well, conducting short wells from the development of the produced formation across the horiz ntalnoy of the ground well in bringing together the formation.

The invention is illustrated by drawings.

Figure 1 in the mining specifications for the preparation of the excavation site for mining schematically shows the inclined part 1 of the surface well, its horizontal part 2, drilled from the conveyor workings 3 short formation wells 6, the mounting chamber 4 and the ventilation workout 5, as well as the direction of the angle of incidence formation α.

Figure 2 shows a schematic diagram of the location of the inclined part 1 of the well and horizontal parts of the well 2 in the plane of the developed formation and well 2 'in the plane of the adjacent formation, as well as the location of the mounting chamber 4 in the developed layer in preparation for the excavation section for development.

The method is as follows.

In the mine field, in accordance with the schedule for the preparation of the coal seam suite for development, a series of inclined horizontal (or vertically horizontal) wells are alternately drilled from the earth's surface to the developed and adjacent coal seams. In this case, for example, the inclined part 1 of the well (FIGS. 1 and 2) is carried out at an angle to the formation of coal seams so that it is more technologically feasible to transfer the well from the rock part to the horizontal part 2 'in the plane of the close-in side of the produced bed to the design length in accordance with the technical capabilities of the rig. Then, the inclined part of the surface well is deepened to approach the rocks of the immediate roof of the developed formation, the well is brought out into its plane, and horizontal drilling of the horizontal part 2 (Fig. 2) along the developed layer is carried out without completing the future (or actual) mounting chamber 4.

In the case when it is planned to mine the coal seam with lavas on the uprising of the seam, the mouth of the surface well is located at the upper boundary of the excavation section, that is, closer to the earth's surface. In the process of drilling a well, its horizontal parts are carried out in the plane of the coal seams by their dip, mainly along the center of the extraction column.

If the mining plan provides for the development of a coal seam with lavas along strike, then the surface well is located in the part of the extraction column opposite to the mounting chamber, and at a distance of 1/3 of its width in the upper part. The horizontal parts of the borehole both in adjacent coal seams and in the developed seam are carried out with a negative elevation angle diagonally along the length of the seam section, ranging from 1/3 of the width of the extraction column from the upper (ventilation) mine to 1/3 of the width of the excavation section from the bottom (conveyor) production. This geometric arrangement of the horizontal parts of the well contributes to the discharge of the wellbore fluid.

To drain the wells drilled in the near-by-worked coal seams, conduct from the development of the developed seam and equip short underground wells oriented to the bottomhole part of the horizontal wellbore. Thus drilled underground wells before the start of treatment work are used to drain fluid from a surface well with its horizontal part, which initially functions as a well for preliminary degassing of an adjacent formation. During the treatment process, these wells are isolated from the mine atmosphere and used to extract methane from the worked out space.

In order to increase the efficiency of preliminary degassing of the developed coal seam, ascending formation wells are additionally carried out in its plane in the direction of the horizontal part of the surface well. Through short formation wells drilled near the bottomhole part of the horizontal wellbore of the surface well, a hydraulic connection is created between the long horizontal part of the well and short formation wells both for draining the wellbore and preliminary degassing of the coal seam being worked out. At the same time, short stratum wells are equipped with a device for draining well fluid. During the treatment period, they are isolated from the mine atmosphere, and methane released from the formation due to aerological connection between the horizontal part of the well and short formation wells is led to the surface through a surface well, at the mouth of which a mobile vacuum pump station is installed.

In cases where the length of the excavation sections exceeds the horizontal part of the well that is technically feasible for drilling, in addition to the surface well with its horizontal part oriented in the direction of the mounting chamber, an on-ground well will be directed towards it with the horizontal part being placed in the undermined coal seam. To drain the well, short wells are also drilled from the development of the producing formation across the horizontal part of the surface well in the adjacent formation. In the process of cleaning work, when the horizontal part of an additionally drilled surface well loses its integrity due to unloading of a nearby formation or its fracture, the well functions as a flank, extracting methane and diverting it to the surface under the vacuum created by the vacuum pump, which is installed at the mouth of an additional surface well with its horizontal part in a contiguous formation drilled above the assembly chamber in the area of the discharge effect of treatment operations on the contiguous formation.

Two surface wells are drawn in excavation areas with unstable hypsometry, the width of which exceeds 300-350 m, with horizontal shafts located along the extraction column in the upper and lower (or left and right) widths of the parts of the excavation section.

To create a hydraulic connection between the horizontal parts of the surface wells and underground wells, drilling tools can be used taking into account the location parameters of the faces of both systems of wells, or hydraulic fracturing of degassed developed and adjacent coal seams through surface wells to form cracks, for example, interval formation fracturing during horizontal shafts of surface wells. It is possible to use hydraulic fracturing of coal seams through underground wells drilled near the faces of horizontal parts of surface wells.

The implementation of the method will simplify the degassing system of the mine, eliminating the laying of degassing pipelines in the mine workings of coal mines, increase the efficiency of degassing of the developed and adjacent coal seams by implementing it both preliminary and in the process of cleaning operations.

Information sources

1. Methodological recommendations on the degassing of coal mines (RD-15-09-2006). Series 05. Issue 14 / Coll. author - M .: OJSC "Scientific and Technical Center for Safety in Industry", 2007. - 256 p.

2. Puchkov L.A., Slastunov S.V., Kolikov K.S. Extraction of methane from coal seams. - M.: Publishing. Moscow State Mining University, 2002. - 383 p.

3. Guidelines for the degassing of coal mines. - M .: Nedra, 1975 .-- 189 p. (prototype).

Claims (4)

1. The method of degassing coal mines, including conducting from the earth's surface of inclined horizontal / vertical horizontal wells with the output of their bottomhole parts in a horizontal plane, equipping the wells with casing pipes, connecting to a vacuum pump and extracting methane from the carbonaceous massif, characterized in that a mine field conducts a series of surface wells in excavation sections being prepared for mining with the withdrawal of the horizontal part of the wells into the coal in the developed and adjacent formations, in addition to short wells isolated from the mine atmosphere are carried out and equipped in the excavation sections of the earth’s wells, with the help of which they create a hydraulic connection between the surface-oriented well in the direction of the mounting chamber and the underground ones, with the possibility of draining the borehole fluid, while horizontal parts are being prepared for the extraction section for lava mining the surface well is carried out along the axis of the excavation section, and when preparing the excavation section for lava mining along strike, it extends diagonally along along the length of the section of the degassed formation, with a negative elevation angle of the horizontal part of the well. 2. The method according to claim 1, characterized in that on an extended excavation section, in addition to a surface well with a horizontal part oriented in the direction of the mounting chamber, a counter ground well is placed with its horizontal part being placed in the coal bed being worked out. 3. The degassing method according to claim 1, characterized in that when methane is extracted from the developed formation, short wells are carried out in its plane by rising upright oriented to the horizontal part of the surface well. 4. The method of degassing according to claims 1 and 2, characterized in that when methane is extracted from the produced near formation, short wells are carried out from the production of the produced formation across the horizontal part of the surface well in the adjacent formation.

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