RU2447290C1 - Method for degassing of coal beds - Google Patents

Method for degassing of coal beds Download PDF

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RU2447290C1
RU2447290C1 RU2010145974/03A RU2010145974A RU2447290C1 RU 2447290 C1 RU2447290 C1 RU 2447290C1 RU 2010145974/03 A RU2010145974/03 A RU 2010145974/03A RU 2010145974 A RU2010145974 A RU 2010145974A RU 2447290 C1 RU2447290 C1 RU 2447290C1
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coal
gas
bed
wells
low
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RU2010145974/03A
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Russian (ru)
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Игорь Юрьевич Зайцев (RU)
Игорь Юрьевич Зайцев
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Закрытое акционерное общество "Инконко"
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Abstract

FIELD: mining.
SUBSTANCE: method includes drilling of wells, casing of wells and cementing of the annular space, identification of at least one bed with low gas impermeability in a coal rock massif above at least one coal bed aimed for degassing, opening of coal beds and enclosing rocks, mechanical impact at coal beds, removal of working fluid, recovery of water along the entire thickness of the coal rock massif below the bed with low gas impermeability, production of gas along the entire thickness of the coal rock massif. Mechanical impact at coal beds is carried out with application of bed hydraulic rupture or gas-dynamic impact at the bed, or pneumatic hydrodynamic impact at the bed or hydraulic impact in cavitation mode. At least one bed with low gas impermeability is identified in the coal rock massif, arranged below the degassed coal bed, the coal rock massif is opened in the interval limited with the bed at the bottom having low water permeability and with the bed having low gas permeability at the top. Additional wells are drilled on the ways of gas migration and in areas of its accumulation.
EFFECT: invention provides for most complete extraction of gas contained both in coal beds and in enclosing water-saturated rocks.
6 cl, 6 dwg

Description

The invention relates to the coal industry and can be used in the production of methane both for its industrial use and for the degassing of developed coal seams in order to ensure safe working conditions for miners.
Known - copyright certificate SU No. 1566046, class. E21F 7/00, 1990 - a method of degassing a coal seam suite, including drilling a group of wells from the surface, perforating casing strings in the plane of the coal seams, cyclic injection of working fluid into the coal seams in the mode of hydraulic separation through a group of wells until a hydraulic breakdown between them is achieved, followed by pumping from the treated coal mass of the working fluid and extracting gas, while the working fluid is pumped out through the well, the bottom of which is the lowest located at the fall of the lower formation, and go to a certain level, and gas extraction is carried out from the remaining wells of the group.
The disadvantages of the method include the low efficiency of degassing of coal seams, because Perforation of casing strings is carried out only in the plane of coal seams; therefore, water from the host rocks enters the coal seam and prevents degassing of the coal seam. Another disadvantage is the uncontrolled accumulation of gas in the host rocks located between the coal seams, and its possible breakthrough to the surface or into the coal seams located above the degassed seam, which may be in development. Gas pops up at the uprising of the reservoir and can get into the mine workings, which are away from the degassed area. In addition, gas dissolved in water saturating the strata of rocks located between the coal seams is not involved in production. There is a gas contamination of the host rocks, since gas from the coal seam enters the overlying rock layers above the roof of the degassed seam under the influence of gravitational forces.
Known - patent RU No. 2117764, class. E2 F 7/00, 1998 - a method of degassing coal seams, including drilling a well, oriented interval hydraulic fracturing in the direction from the bottom to the wellhead, removing the working fluid and suction of gas, while the degassed mass is drilled with wells, and the tensile strength of the rock layers is determined containing coal seams, hydraulic fractures are created in the soil and roof of each formation, and the location of hydraulic fractures is selected from certain conditions.
The disadvantage of this method is the uncontrolled accumulation of gas in the host rocks and its possible breakthrough to the surface or into coal seams located above the degassed seam, which may be in development. The process of gas leakage from the coal seam into the host rocks is ensured by creating cracks communicating the coal seam and the host rocks.
Known - patent RU No. 2136890, class. E21F 7/00, 1999 - a method of degassing coal seams, including drilling a well towards the roof of the produced seam, casing part of the wells, connecting them to a pump and vacuum station and extracting gas from the undermined coal seam, while evaluating while drilling in the coal seam the strength of the rock layers, distinguish the most durable layer of rocks with a deviation from the arithmetic mean value of the strength of the overburdened rocks exceeding 10%, located at a minimum distance from the undermining layer and having its own power the thickness is not less than 0.1a, where a is the width of the lava, the undermining layer, this strong layer is considered gas-shielding, and the well is drilled to the soil of the gas-shielding layer.
The disadvantage of this method is the obligatory availability of mining for coal sampling in the degassing area for the formation of decompression cracks. Therefore, the application of the method is limited by the depth of mining for the purpose of coal mining. For deep seams of coal, the use of the method becomes ineffective, since the cost of mining coal increases with depth.
Known - patent RU No. 2339818, class. E21F 7/00, 2008 - a method of degassing a suite of adjoining coal seams with a pillar mining system, mainly during the first development of one of the seams in the suite, including determining the zone of greatest gas accumulation in which discharge cavities form during the clearing of the developed seam, drilling from the surface of the directional well, the working part of which is oriented parallel to the plane of the layers and is located in the discharge cavities under the shielding rocks, sealing the wellhead and unloading coal the main array, followed by suction of gas from the well using vacuum pumps, while the location of the directed well on the surface is chosen between the two excavation pillars of the reservoir being planned for development, and the directed well is multilateral, namely, after drilling the indicated working part of the directed well, which is placed along one of the extraction columns, additionally form its other working part with orientation in the opposite direction relative to the last and along another of the excavation column, then each working part of the directional well is branched into at least two shafts, each of which, when drilling, is oriented parallel to the working part of the well in the plane of the discharge cavities, and the drilling process of the directed multilateral well is completed before the preparation of the extraction columns for the treatment recess, and unloading the coal-bearing massif is carried out in the preparation of the extraction columns for the treatment recess along the developed seam and in stages in order to intensify the gas recovery process of the said coal a solid array, for which, first, mechanical action is performed on the coal-bearing massif through the working parts of the directional multilateral well, for example, by pumping liquid under pressure in a hydro-pulse mode, vacuum pumps are connected to the directed well and the gas released from it from the cracks of the unloaded coal-bearing mass is sucked out the area of the working parts of the directional well, and then from the workings that delineate the extraction columns, drill unloading wells are drilled in the direction p position the working parts of the directional well and produce mechanical impact through them on the coal-bearing massif, for example, by camouflage blasting, which provides the formation of an additional system of collector cracks in the coal-bearing massif, which conduct gas towards the directional well, which is aspirated as it enters the well, then Conducting treatment works in the extraction columns of the developed formation, the unloading of the coal-bearing massif continues due to the displacement of the rocks, and into the formation formed during the treatment The work of the discharge cavity above the undermined reservoir produces gas from the destroyed coal-bearing massif, followed by its suction through the directional well; upon completion of the treatment works in the extraction columns of the developed reservoir, gas continues to be extracted from the worked-out coal-bearing massif while the worked-out reservoir is worked out and gas is exhausted from the worked-out space of this reservoir, moreover, the gas suction from the directed well continues after the development of coal seams in the formation, later on until the development of the next yemochnyh pillars producing formation is drilled following directions of multilateral wells and repeat the cycle of works for the unloading and degassing of coal-bearing massif.
The disadvantage of this method is the drilling of expensive multi-lateral horizontal wells. Therefore, the method is applicable for powerful coal seams with a small depth. In the case of deep-seated low-power coal seams, the method becomes unprofitable.
The technical result of the invention is to provide the most complete extraction of gas contained in both coal seams and in the host water-saturated rocks, preventing uncontrolled gas leaks into the seams lying above the degassed seams, preventing the gas seams of coal seams located above the degassed coal seams, i.e. . ensuring safe working conditions for miners, thanks to the joint selection of gas and water from the coal seam and the surrounding rocks. The method is most effective for groups of low-power coal seams located in the host water-saturated rocks.
The specified result is achieved by the fact that the method of degassing coal seams includes drilling wells, casing wells and cementing the annulus, the allocation in the coal rock mass of at least one layer with low gas permeability over at least one coal seam intended for degassing, opening coal seams and host rocks, for example, by sandblasting or cumulative perforation, mechanical impact on coal seams, removal of the working fluid, water withdrawal throughout the thickness of the coal-bearing rock reservoir below the array with a low gas tightness, gas production over the entire thickness ugleporodnogo array. In addition, at least one layer with low water permeability, located below the degassed coal seam, is separated in the coal-bearing massif, and the carbonaceous mass is opened in an interval limited from below by a low-permeability formation and from above by a low gas-permeability formation.
Wells can be vertical or have an angle of inclination. Inclined wells are drilled when drilling vertical wells is not possible due to limited surface area, for example, the location of buildings.
As a mechanical effect on coal seams in order to increase permeability, hydraulic fracturing, or gas-dynamic impact on the formation, or pneumohydrodynamic effect on the formation, or hydraulic action in the cavitation mode can be used.
In this case, the autopsy and mechanical action is carried out in wells in degassed coal seams and between the degassed coal seams, and additional wells are drilled on the gas migration paths and in the areas of its accumulation.
As layers with low gas permeability and water permeability can be used low-power coal seams.
To increase gas production and reduce gas leakage when the formations are inclined, additional rows of horizontal wells are drilled perpendicular to the formation uprising. In the event of a breakthrough and gas movement along the uprising of the reservoir, it is selected by horizontal wells.
To reduce gas leaks with an inclined arrangement of the wellbore, at least in one row perpendicular to the uprising of the wellbore, they are placed at a closer distance from each other than the rest of the drilled area.
To reduce gas leaks with an inclined formation in vertical wells, sidetracks are drilled perpendicular to the formation uprising. Sidetracks are located at intervals at which gas leaks are expected in the drilled area. Sidetracks are drilled in at least one row of wells perpendicular to the uprising of the strata.
In the case of an inflection of layers at the upper points of an inflection, technogenic gas deposits can form. To select this gas, additional wells are drilled to the places of inflection of the strata.
In the case of displacement of formations in the places of shear, technogenic gas deposits can form. For the selection of this gas, additional wells are drilled to the places of shear formation.
Figure 1 shows the layout of the wells; figure 2 is a section aa of figure 1; figure 3 - arrangement of wells; figure 4 - layout of wells; figure 5 - arrangement of wells; Fig.6 is a section bb In Fig.5.
The method is as follows. Wells 1 are drilled from the surface into the coal-bearing massif (Figs. 1, 2) to a depth exceeding the depth of the lowest coal seam 2 intended for degassing, geophysical surveys are conducted in well 1 and the position of at least one seam 3 s is determined the lowest gas permeability, located above all coal seams 2, scheduled for degassing. Wells casing and cementing annulus. The coal seams 2 and the host rocks 4 are opened, for example, by sandblasting or cumulative perforation, in the range of 5 depths below the bottom of the seam 3 with low gas permeability to a depth exceeding the depth of the lowest coal seam 2. Carry out a mechanical action on the coal seams 2, for example , by hydraulic fracturing. Development of well 1 and pumping of water are carried out. Gas production is carried out in self-discharge mode or using pump-vacuum units. When degassing a coal seam 2, part of the gas 7 enters the wells 1 through the coal seam 2 through a system of natural and artificial cracks 6. The other part of the gas 7, under the action of gravity, floats into the water-saturated host rocks 4 and flows through them into the wells 1. Production of gas-saturated water and gas over the entire opening interval to the gas-tight formation 3 allows this gas to be extracted from the carbonaceous massif.
As a result of the simultaneous withdrawal of water from the coal seam 2 and the host rocks 4, an intense pressure drop occurs and, as a result, accelerated degassing of the coal seam 2 and water saturating the host rocks 4, because when water and gas are taken only in the interval of coal seam 2, it is compensated by its fluid flow from below and overlying water-saturated seams 4, which leads to a slowdown in pressure reduction in coal seam 2. As a result of gas evolution from water saturating the host rocks 4, additional extraction is provided water-soluble gas 7.
When low-permeable water-saturated seams 8 located between the degassed coal seams 2, a mechanical effect is carried out on the coal seams 2 and the seams 8, for example, by hydraulic fracturing (Fig. 3). As a result of mechanical action on low-permeable water-saturated seams 8, water is taken from these layers and the flow of water into the coal seams 2 is limited.
At least one formation 9 with low water permeability, located below the degassed coal formation 2, is isolated in the coal-rock massif (Fig. 4), autopsy and mechanical action is performed in the wells 1 in an interval limited from below by the formation 9 with low permeability, and above by the formation 3 with the lowest gas permeability. Allocation of the interval limited from below by a seam 9 with low water permeability, and from above by a seam 3 with low gas permeability, allows you to select the development object in a coal-bearing massif and reduce the cost of pumping water in order to reduce the pressure in coal seams 2, since in this case the flow of water from underlying water-saturated intervals.
When the inclined location of the layers (Fig.5, 6) determine the path of migration and accumulation of gas 7 and drill additional wells 10 in order to select it.

Claims (6)

1. A method of degassing coal seams, including drilling wells, casing wells and cementing the annulus, the allocation in the coal rock mass of at least one layer with low gas permeability over at least one coal seam intended for degassing, opening the coal seams and host rocks, mechanical impact on coal seams, removal of working fluid, water withdrawal throughout the thickness of the carbonaceous massif below the formation with low gas impermeability, gas production throughout the thickness of the carbonaceous mass willow.
2. The method according to claim 1, characterized in that the mechanical action on the coal seams is carried out using hydraulic fracturing, or gas-dynamic effects on the formation, or pneumohydrodynamic effects on the formation, or hydraulic action in the cavitation mode.
3. The method according to claim 1, characterized in that at least one layer with low water permeability, located below the degassed coal seam, is separated in the carbon rock massif, the carbon rock mass is opened in the interval bounded from below by the low water permeability reservoir and from above by the reservoir with low gas permeability.
4. The method according to claim 1 or 2, characterized in that the opening and mechanical action on the coal seams is carried out in wells in degassed coal seams and seams located between the degassed coal seams.
5. The method according to claim 1 or 3, characterized in that as the layers with low gas permeability and water permeability, low-power coal seams can be used.
6. The method according to claim 1, characterized in that additional wells are drilled on the gas migration paths and in the areas of its accumulation.
RU2010145974/03A 2010-11-11 2010-11-11 Method for degassing of coal beds RU2447290C1 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103321669A (en) * 2013-07-08 2013-09-25 中国矿业大学(北京) Method for increasing permeability of low-permeability coal seam by means of deep-hole directional pre-splitting blasting
CN103470298A (en) * 2013-10-02 2013-12-25 河南理工大学 Design method of hole-drilling and hole-forming process scheme for drainage of outburst coal seam
CN104234738A (en) * 2014-07-21 2014-12-24 河南理工大学 Low-permeability coal bed multi-branch directional drilling seam cutting anti-reflection method
CN105673063A (en) * 2016-01-06 2016-06-15 中国矿业大学 Impact-disaster control method for large-dip-angle gas-containing thick coal seam

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1298404A1 (en) * 1985-07-02 1987-03-23 Московский Горный Институт Method of degassing coal-bearing strata
RU2117764C1 (en) * 1996-04-08 1998-08-20 Институт угля СО РАН Method for degassing of coal seams
RU2121062C1 (en) * 1997-04-15 1998-10-27 Московский государственный горный университет Method of withdrawal of methane from coal bed
RU2136890C1 (en) * 1998-05-07 1999-09-10 Государственный научно-исследовательский институт горной геомеханики и маркшейдерского дела - Межотраслевой научный центр (ВНИМИ) Method for degassing of coal seams
EP1440220A1 (en) * 2001-10-30 2004-07-28 CDX Gas, LLC An entry well with slanted well bores and method
RU2339818C1 (en) * 2007-05-14 2008-11-27 Геннадий Дмитриевич Задавин Degassing method of set of contiguous coal beds for barrier method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1298404A1 (en) * 1985-07-02 1987-03-23 Московский Горный Институт Method of degassing coal-bearing strata
RU2117764C1 (en) * 1996-04-08 1998-08-20 Институт угля СО РАН Method for degassing of coal seams
RU2121062C1 (en) * 1997-04-15 1998-10-27 Московский государственный горный университет Method of withdrawal of methane from coal bed
RU2136890C1 (en) * 1998-05-07 1999-09-10 Государственный научно-исследовательский институт горной геомеханики и маркшейдерского дела - Межотраслевой научный центр (ВНИМИ) Method for degassing of coal seams
EP1440220A1 (en) * 2001-10-30 2004-07-28 CDX Gas, LLC An entry well with slanted well bores and method
RU2339818C1 (en) * 2007-05-14 2008-11-27 Геннадий Дмитриевич Задавин Degassing method of set of contiguous coal beds for barrier method

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103321669A (en) * 2013-07-08 2013-09-25 中国矿业大学(北京) Method for increasing permeability of low-permeability coal seam by means of deep-hole directional pre-splitting blasting
CN103321669B (en) * 2013-07-08 2015-05-27 中国矿业大学(北京) Method for increasing permeability of low-permeability coal seam by means of deep-hole directional pre-splitting blasting
CN103470298A (en) * 2013-10-02 2013-12-25 河南理工大学 Design method of hole-drilling and hole-forming process scheme for drainage of outburst coal seam
CN103470298B (en) * 2013-10-02 2015-07-01 河南理工大学 Design method of hole-drilling and hole-forming process scheme for drainage of outburst coal seam
CN104234738A (en) * 2014-07-21 2014-12-24 河南理工大学 Low-permeability coal bed multi-branch directional drilling seam cutting anti-reflection method
CN105673063A (en) * 2016-01-06 2016-06-15 中国矿业大学 Impact-disaster control method for large-dip-angle gas-containing thick coal seam

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Effective date: 20141112