RU2091574C1 - Method of underground gasification - Google Patents

Abstract

FIELD: processing of thick brown coal seams by underground gasification. SUBSTANCE: the offered method includes injection of gel-forming compounds in volume V=0.01xTu.s.xSxW cu.m, where Tu.s. is thickness of processed top bands; S is area of seam opened by holes; W is maximum hygroscopic moisture content in per cent. EFFECT: higher rate of recovery of coal substance due to treatment of top bands with gel-forming compounds and their coagulation. 2 cl, 1 dwg

Description

 The invention relates to mining and can be used in underground coal processing.

A known method of gasification of coal, which consists in the supply of a gaseous oxidizer, blast (air, steam-air mixture, etc.) through the wells drilled to the coal seam, the filtration breakdown between them and subsequent gasification. At the exit from the diverting wells receive energy combustible gases [1]
However, due to the fact that the gas heated at about 1000 ^o C at the reaction surface of the coal seam is concentrated at the upper bundles, the reaction surface (bottom) has an inclined position of up to 20-30 ^o to the soil [2], as a result of which the upper bursts of coal are preferentially burned out.

 Closest to the invention by the sequence of operations is a method [3] comprising plugging overlying rocks during gasification. The method prevents the penetration of water and leakage of blast in the gasification centers. The main disadvantage is that the method, as well as the analogue, is implemented with an inclined orientation of the reaction surface, which led to faster burnup of the upper packs of coal, as well as the fact that packs are often used (gasified) incompletely.

 The aim of the invention is to increase the completeness of the use of coal matter from powerful coal seams due to the uniform gasification of the seams throughout the power.

The goal is achieved in that the upper packs of coal seams are pretreated with gelling agents containing a solution of water glass or ammonium chloride or sodium bicarbonate, the gelling agent is injected in a volume of V 0.01 • m _vp • S • W, m ³ , where M _vp power of processed packs; S the area of the reservoir, opened by wells for gasification, m ² ; W maximum hygroscopic humidity, while the process of filtration failure, gasification of the formation begin in the lower coal bundle.

 The second distinguishing feature is that in order to increase the efficiency of the method implementation in dense, slightly disturbed packs of coal, hydraulic fracturing is performed before the injection of gel-forming compounds, followed by pumping of water.

 The drawing shows a schematic diagram of the implementation of the method.

The gasified formation 1 consists of packs 2, 3, 4. The blast hole 5 and diverting wells 6 are first drilled to positions 7 and 8, respectively, and the gelling compositions are pumped into micro- and macrocracks of packs 2 and 3. 5-10% are used as the mentioned compositions solution of water glass or sodium bicarbonate. The volume of injected solution is described below. Then the wells are drilled to the design depths of 9 and 10, the wells are knocked down by filtration failure, for example, pumping air at a pressure of 1.5-2 atm, first P is ignited and gasified (pack 4), and then overlying packs 2 and 3. In some cases if necessary, gasify the formations, the upper packs of which are composed of dense, slightly disturbed coals, they produce hydraulic fracturing followed by (after a drop in water pressure (hydraulic fracturing) pumping water and subsequent injection of gel-forming compounds.
V 0.01 • m _vp • S • W, m ³ ,
where m _vp power of the processed packs; S formation area, opened by wells and prepared for gasification; W maximum hygroscopic humidity, which characterizes the disturbance of the processed packs.

 The implementation of the method is illustrated by an example from the operating conditions of the Angren station "Podzemgaz" PO "Sredazugol", the gasified reservoir in the gas generator section N5 was opened with three blast holes and three by-holes, which were drilled through 20 m in pairs. The layer with a thickness of 8 m is divided by layers of mudstone into 3 packs. The lower 2 m, the middle 4 m and the upper 2 m. When opening the well, we did not drill 2 m to the formation soil and coal samples were taken from the resulting block.

 The average maximum hygroscopic humidity was determined from coal samples.

Затем поместили бюксы в эксикатор с 10%-ным раствором соляной кислоты и, взвешивая через 5 ч, через 35 ч получили максимальное водонасыщение со средним значением

Откуда определяли объем закачки гелеобразующих составов в среднюю и верхнюю пачки
V 0,01 • 6м • (20•2•20) • 5,2 240 м³.To do this, took 10 g of coal from each well and placed in boxes. They were heated to 140 ^o C, and then weighed. Got the following value

Then the bucks were placed in a desiccator with a 10% hydrochloric acid solution and, after weighing after 5 hours, after 35 hours the maximum water saturation was obtained with an average value

Where did they determine the volume of injection of gelling agents into the middle and upper packs?
V 0.01 • 6m • (20 • 2 • 20) • 5.2 240 m ³ .

In this case, 240/6 40 m ^{3 of} gel-forming composition in the form of a solution of sodium bicarbonate in water (10% solution) was pumped through each of the wells. Then, the well was drilled to the design depth (formation soil) and 2 days after the injection of the composition, filtration disruption, ignition and gasification of the formation were performed. Wells drilled after gasification showed full recovery of reserves at the processing site, losses from incomplete gas extraction amounted to 3% compared to standard 25-30%
Compared with the prototype, which is the basic option, the proposed method provides a reduction in the loss of coal substance in the bowels, its more complete and efficient use.

 Literature.

 1. A.P. Dmitriev, S.A. Goncharov, Thermodynamic processes in rocks. M. Nedra, 1990, p. 226-245.

 2. V.N. Cossack. Investigation of the manifestation of rock pressure during shaftless thermal processing of coal seams, Diss. for the competition step. Cand. tech. sciences. M. MGI, 1966, VNIIIPromgaz, p. 116a.

 3. Copyright certificate of the USSR 1764358, cl. E 21 B 43/295, 1989.

Claims (2)

1. A method of underground gasification of coal seams, including opening a coal seam with two well systems, pre-treating overlying seams, creating a blast channel between the wells with filtration failure, igniting the seam, blowing and pumping productive gas, characterized in that, in order to increase the fullness of use of coal substances from powerful coal seams due to the uniform gasification of the seams throughout the power, pre-process the upper packs of coal seams with gelling agents and containing a solution of water glass or ammonium chloride or sodium bicarbonate, gelling agents are pumped in a volume
V 0.001 m _{in . n} • S • W,
where m _{in . p the} power of the processed packs, m;
S formation area, autopsy wells for gasification, m ² ;
W maximum hygroscopic humidity,
while the process of filtration failure and gasification of the formation begin on the lower coal bundle.  2. The method according to claim 1, characterized in that, in order to increase the efficiency of gasification in dense weakly broken coal packs, a hydraulic fracturing is performed before laying gel-forming compositions with subsequent pumping of water.