SU1481409A1 - Method of methanization of water-saturated coal deposits - Google Patents

Abstract

The invention relates to the mining industry and can be used in the coal mining industry in the gasification of watered coal seams (UE). The goal is to increase methane output by maintaining optimal pressure in the UE. For this purpose, an injection well (PS) and a production well (DS) are drilled in the UE. Have the NA in the crease of the fold developed UE, and DS - in its lower part. The fracture of the HC and DS is fractured and the gas pressure is measured. The drills are drilled to a depth where the pressure of the reservoir water is equal to the pressure of the gas, equip the DW with a gas outlet column. The shoe of the latter is set at a level where the water pressure is greater than the hydrostatic, but less than the gas pressure. Cold air is supplied to the HC with simultaneous ejection of formation water into the DS. A gas (air) zone is created, which is accompanied by pressure stabilization in it. The UE is ignited, it is heated to 700–1500 K, and water or heated steam is supplied to the heated UE through NS. Combustible gases are pumped out of the DS, the main component of which is methane. At high temperatures at the bottom of the DS, cold water is fed into its annulus. With a decrease in the quality of methane, pressure in the DS is controlled by varying the depth of the gas exhaust shoe. 1 il.

Description

one

The invention relates to mining and can be used in the coal mining industry during the geotechnical development of gasification of watered coal.

The purpose of the invention is to increase the methane yield by maintaining optimum pressure in the coal seam by forming a gas zone of increased pressure at the bottom of the production well.

О About

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The drawing shows the implementation of the proposed method.

The method is carried out as follows.

A watered coal seam is drilled, for example, in the crest of the fold of the injection well 1, and on the wings - with the production well 2 to the bottom of the coal seam. The hydraulic fracturing is connected to the bottom of injection 1 and the production of 2 wells, and the hydraulic fracture pressure R is measured.

After that, a well 3 is drilled in the production well 2 to a depth h, which corresponds to the fracturing pressure in the formation. The depth of the well 3 is determined from the formula

,

where H is the depth of the production well;

h is the depth of the well; P - measured on the surface

fracture pressure; t is the volumetric weight of produced water.

The depth h provides control of the synthesis pressure from hydrostatic to fracture pressure. After that proceed to the arrangement of wells. Injection well 1 is adapted to separate air and water injection. Thermally insulated gas exhaust pipe 4 is lowered into production well 2, its shoe is installed at a predetermined design depth, where the pressure of the formation water pressure is greater than hydrostatic but less than the fracture pressure.

After the wells are set up, an artificial gas cap with a self-regulating water gate in the production well is created in the reservoir by injecting cold air into the injection well 1 while simultaneously producing water from the production well 2. The gas header is created to break the air through the production well 2, which is accompanied by pressure stabilization in the gas cap at the level of the reservoir water head at the gas exhaust pipe shoe 4. Then a stable pressure of the reservoir water is fixed almost equal to the gas pressure in the gas th cap.

In the next work stage, the coal seam is ignited at the bottom of the injection well 1 by any known method. By injecting air into this well, coal is crushed to a temperature of about 1500 K. Heating of the coal to this temperature is necessary because the methane synthesis reaction is endothermic and the subsequent methane synthesis is complete.

five

35 40 45

50 55

due to the heat accumulated in the reservoir during cooling of the latter from 1500 to 700 K.

When the temperature reaches 1500 K in the reservoir, the air supply to the injection well 1 is stopped and gasified reagent - water vapor or water is supplied through it to form methane by the reaction 2C + + 2H20 CH4 + C02.

The resulting gases, predominantly methane, with a pressure in the synthesis zone close to the fracture pressure, are discharged, pushing the water shutter, through the exhaust pipe 4 to the surface, where the resulting products are disintegrated, their physical body is disposed of.

The duty cycle of methane synthesis (water supply) is completed when the well productivity of methane starts to decrease dramatically. In order to obtain 100 m3 of methane, with this method, 1000 me of air is consumed (at the stage of reservoir heating) and approximately 150 kg of natural water. At the same time, about 100 kg of coal bed are gasified.

Claims (1)

After several cycles, the downhole temperature in the production well 2 can rise to high unacceptable values, for example above 600 K, which is recorded by the downhole thermometer 5. In this case, to prevent overheating of the exhaust pipe 4 and the casing of the production well 2 into the annulus between the production well 2 and the gas exhaust pipe 4, a stream of cold water is supplied to cool them and to reduce and maintain the bottomhole temperature of the well and the gases produced at a level not higher than 600 K. In this case, the steam-gas cm The mixture is also discharged through the exhaust gas pipe 4 to the surface, fed to a heat exchanger and a separator, where physical heat is utilized and the synthesis products are separated from the products of combustion and the liquid phase. Invention Formula The method of methanization of watered coal deposits, including the drilling of injection and production wells on the coal seam, sealing the wellhead, connecting the bottom of the wells under the pressure of hydraulic fracturing, equipment of the production well of the gas extraction column, ignition of the formation at the injection well, alternate supply of heated air for heating the formation to 700–1500 K and water into the heated formation for the synthesis of combustible gases, sequential removal of products of combustion and synthesis through the production well and cooling of the production that, in order to increase the methane output by maintaining optimum pressure in the coal seam by forming a gas zone at the bottom of the production well, goa production wells doburivayut below of gases the bottom of the coal seam to a depth where the pressure of the reservoir water pressure is equal to the hydraulic fracture pressure; the gas discharge column is lowered into the production well to a depth where the pressure of the formation water pressure is more hydrostatic but less than the hydrostatic pressure, and air is fed to the bottom of the production well through the injection well before the formation of the gas zone from the end of the gas exhausting column to the roof of the coal seam, while in the process of the synthesis of combustible make pressure control in the gas zone by varying the depth of the gas exhaust pipe installation. Hoopta 1 melts Water is cool - f