scholarly journals DYNAMICS OF GAS EMISSION FROM EXPOSED SURFACE OF GAS-BEARING COAL SEAMS HAVING MEDIUM THICKNESS

2021 ◽  
Vol 13 (3) ◽  
pp. 441-448
Author(s):  
Nikolai KACHURIN ◽  
◽  
Galina STAS ◽  
Alexander KACHURIN ◽  
◽  
...  
Keyword(s):  
Coal Seam ◽  
Mathematical Models ◽  
Driving Forces ◽  
Mathematical Physics ◽  
Gas Release ◽  
Coal Seams ◽  
Excessive Pressure ◽  
Methane Release ◽  
Mine Workings ◽  
Gas Bearing

The goal of the research was to clarify the regularities of the dynamics of gas release from the surface of the outcrop of the developed coal seam. The main research methods were theoretical methods of mathematical physics and non-equilibrium thermodynamics. Gas-bearing coal seams are usually mined underground. When driving development workings, outcropping surfaces of gas-bearing coal seams appear and gases in the seams under excessive pressure are released into the atmosphere of the mine workings. Gas-bearing coal seams are usually mined underground. When driving preparatory workings, surfaces of outcropping of gas-bearing coal seams arise and gases that are in the seams under excessive pressure are released into the atmosphere of the mine workings. The most important gas-dynamic characteristic of this process is the rate of gas release, which represents the volume of gases released from a unit area of exposure of a coal seam per unit of time. A generalized law of resistance for gas filtration in a rock mass is recommended, and a fairly rigorous thermodynamic substantiation is given. It is shown that the densities of gas mass flows in accordance with the postulate of their linear relationship with the driving forces are determined by the Onsager relation. The results obtained and their discussion is presented. Mathematical models are proposed for engineering calculations of the dynamics of methane release from the outcropping surface of medium-thick coal seams. The error of the adopted approximations does not exceed 3%. The intensity of methane release is directly related to the planogram of work in the working face. Analysis of this dependence indicates that during the extraction cycle, methane release increases due to an increase in the area of the gas-release surface. The main conclusions are as follows: mathematical modeling of the processes of gas movement in a porous sorbing medium using approximate mathematical models representing linearized equations of mathematical physics; the regularities of the dynamics of the rate of gas release from the surface of the outcrop of a gas-bearing coal seam is the theoretical basis for the mathematical description of the process of gas release; the use of a linearized hyperbolic filtration equation most accurately describes the processes of methane release from the outcropping surface of mined coal seams.

MATHEMATICAL DEGASATIONMODELS OF COAL BANDS, RELEASED INTO MINING FACES

2019 ◽  
Vol 4 (1) ◽  
pp. 249-258
Author(s):  
A.N. Kachurin ◽  
◽  
V.K. Demin ◽  
D.N. Shkuratskyi ◽  
P.I. Karnachev ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mathematical Models ◽  
Coal Seams ◽  
Methane Release ◽  
Full Capacity

Mathematical models have been developed for the degassing of roofing coal packs discharged into treatment faces when mining powerful flat coal seams with one face. It was shown that when a powerful coal seam is excavated to full capacity with one face with the release of a sub roofing pack, methane release from the sub roofing pack of a disturbed structure will be formed according to the laws of gas motion in fractured-porous sorbing media.

Optimization of Coal Seam Connectivity via Multi-Seam Pinpoint Fracturing Operations in the Walloons Coal Measures, Surat Basin

2021 ◽  
Author(s):  
Vibhas J. Pandey ◽  
Sameer Ganpule ◽  
Steven Dewar
Keyword(s):  
Coal Seam ◽  
History Matching ◽  
Design Matrix ◽  
Coal Seams ◽  
Major Step ◽  
Well Completion ◽  
Eastern Australia ◽  
Treatment Designs ◽  
Coal Measures ◽  
Gas Bearing

Abstract The Walloons coal measures located in Surat Basin (eastern Australia) is a well-known coal seam gas play that has been under production for several years. The well completion in this play is primarily driven by coal permeability which varies from 1 Darcy or more in regions with significant natural fractures to less than 1md in areas with underdeveloped cleat networks. For an economic development of the latter, fracturing treatment designs that effectively stimulate numerous and often thin coals seams, and enhance inter-seam connectivity, are a clear choice. Fracture stimulation of Surat basin coals however has its own challenges given their unique geologic and geomechanical features that include (a) low net to gross ratio of ~0.1 in nearly 300 m (984.3 ft) of gross interval, (b) on average 60 seams per well ranging from 0.4 m to 3 m in thickness, (c) non-gas bearing and reactive interburden, and (d) stress regimes that vary as a function of depth. To address these challenges, low rate, low viscosity, and high proppant concentration coiled tubing (CT) conveyed pinpoint stimulation methods were introduced basin-wide after successful technology pilots in 2015 (Pandey and Flottmann 2015). This novel stimulation technique led to noticeable improvements in the well performance, but also highlighted the areas that could be improved – especially stage spacing and standoff, perforation strategy, and number of stages, all aimed at maximizing coal coverage during well stimulation. This paper summarizes the findings from a 6-well multi-stage stimulation pilot aimed at studying fracture geometries to improve standoff efficiency and maximizing coal connectivity amongst various coal seams of Walloons coal package. In the design matrix that targeted shallow (300 to 600 m) gas-bearing coal seams, the stimulation treatments varied in volume, injection rate, proppant concentration, fluid type, perforation spacing, and standoff between adjacent stages. Treatment designs were simulated using a field-data calibrated, log-based stress model. After necessary adjustments in the field, the treatments were pumped down the CT at injection rates ranging from 12 to 16 bbl/min (0.032 to 0.042 m3/s). Post-stimulation modeling and history-matching using numerical simulators showed the dependence of fracture growth not only on pumping parameters, but also on depth. Shallower stages showed a strong propensity of limited growth which was corroborated by additional field measurements and previous work in the field (Kirk-Burnnand et al. 2015). These and other such observations led to revision of early guidelines on standoff and was considered a major step that now enabled a cost-effective inclusion of additional coal seams in the stimulation program. The learnings from the pilot study were implemented on development wells and can potentially also serve as a template for similar pinpoint completions worldwide.

scholarly journals The results of monitoring of hydroimpulsive disintegration of outburst-prone coal seams using ZUA-98 system

2020 ◽  
Vol 168 ◽  
pp. 00068
Author(s):  
Vasyl Zberovskyi ◽  
Kostiantyn Sofiiskyi ◽  
Rishard Stasevych ◽  
Artem Pazynych ◽  
Jan Pinka ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Rock Mass ◽  
Coal Seam ◽  
High Frequency ◽  
Strain State ◽  
Monitoring And Evaluation ◽  
Dynamic State ◽  
Coal Seams ◽  
Gas Dynamic ◽  
Mine Workings

The paper represents the results of monitoring and evaluation of the efficiency of hydroimpulsive disintegration of outburst-prone coal seams in the stopes of development mine workings using a system of sound detecting facilities. Methods of acoustic emission control have been considered as well as the monitoring tasks to evaluate rock mass conditions before the procedure and after it inclusive of the results of sound accompaniment of hydraulic disintegration of the coal seam. It has been determined that the higher concentration of stresses within the rock mass is, the more efficient action of high frequency self-oscillations of cavitation transmitter is on both the fissuring and changes in gas-dynamic state of the coal seam. It has been recommended to apply a mode of impulsive fluid pumping under the conditions where coal seam is in the stress-strain state.

The Studies on Gas-Bearing Characteristics of Deep Coal Seams in Yanchang Oil and Gas Province, China

2014 ◽  
Vol 962-965 ◽  
pp. 213-216
Author(s):  
Guo Ping Jiang
Keyword(s):  
Coal Seam ◽  
Layer Thickness ◽  
Oil And Gas ◽  
Single Layer ◽  
Gas Content ◽  
Coal Bed ◽  
Coal Seams ◽  
Resource Potential ◽  
Gas Bearing ◽  
Average Layer Thickness

In this paper, four general directions are described to make evaluations and their resource potential; those are coal structure and coal level, gas content of deep coalbed, the coalbed thickness and distribution and the buried depth of coalbed. Coalfields of the study area are mainly Permian and Carboniferous coal seam of Shanxi Formation coal and Benxi group 11 # coal, coal seam depth 1370-1812m. No. 3 coal-seam average layer thickness of 1.6 m, the monolayer most 2 m thick; No. 11 coal-seam in the average layer thickness of 3 m, single-layer thickness of 4.5 m. Predict the amount of coal resources of 17.3 one hundred million t. Predict coal-bed methane resources of 27.68 billion cubic reserve abundance of 104 million square / km2 in. The exploration results show that this region has good development prospects.

scholarly journals Method and equipment for the safe development of preparatory workings in the gas-bearing coal seams

2019 ◽  
Vol 109 ◽  
pp. 00102
Author(s):  
Mykola Trokhymets ◽  
Vira Maltseva ◽  
Yehor Vialushkin ◽  
Volodymyr Antonchik ◽  
Tetiana Moskalova ◽  
...  
Keyword(s):  
Coal Seam ◽  
Mathematical Models ◽  
Mining Operations ◽  
Liquid Injection ◽  
Mathematical Formulas ◽  
Outburst Coal Seam ◽  
The Cost ◽  
The Given ◽  
Gas Bearing

The article describes a method and equipment for the safe development of preparatory working on a gas-bearing, outburst hazardous coal seam by a heading machine. The described method significantly prevents the gas emission during mining operations. Determination of the amount of degassing and relief wells is performed according to the given in article mathematical formulas. This ensures a significant increase in the level of safety processing the preparatory roadway on a gas-bearing, prone to outbursts coal seam by a heading machine. Due to this, the speed of conducting excavation increases and the cost of mining is reduced. The proportionality coefficients of the mathematical models were determined. Mathematical models are used to calculate the number of relief and degassing wells, which are drilled during the impulse hydraulic loosing of the nearby part of the coal seam. Also the duration of liquid injection into a coal seam is also determined. Mathematical models for calculating the number of injection, unloading and degassing boreholes can be used in development of the passports for conducting preparatory workings on a gas-bearing, prone to outburst coal seam by a heading machine with a preliminary impulse hydraulic loosing of the nearby part of a coal seam.

scholarly journals FEATURES OF METHANE RELEASE IN THE WING OF A MINE FIELD DURING MINING OF GAS-BEARING COAL SEAMS

10.31713/m922 ◽  
2020 ◽  
Author(s):  
Elvira Filatieva ◽  
◽  
Valeriy Sokolenko ◽  
Oleksandr Oleynichenko ◽  
Mykhailo Filatiev ◽  
...  
Keyword(s):  
Coal Seams ◽  
Mine Field ◽  
Methane Release ◽  
Gas Bearing

scholarly journals THEORY AND PRACTICE OF DETERMINING THE CATEGORY HAZARD OF COAL MINES BY THE GAS FACTOR

2021 ◽  
Author(s):  
Elvira Filatieva ◽  
◽  
Aleksandr Oleinichenko ◽  
Mykhailo Filatiev ◽  
Valerii Sokolenko ◽  
...  
Keyword(s):  
Experimental Data ◽  
Coal Mines ◽  
Field Studies ◽  
Theory And Practice ◽  
Gas Release ◽  
Coal Seams ◽  
Working Face ◽  
Gas Bearing ◽  
Enclosing Rocks ◽  
Safe Mining

A comparative analysis of the theoretical and practical definition of the category hazard of coal mines by gas factor based on experimental data obtained in real conditions of mining gas-bearing coal seams is presented. The mine's hazard category by gas factor is determined in accordance with the current regulatory document. The processing of experimental data obtained in field studies leads to contradictions in the requirements for the safe mining of gas-bearing coal seams. The necessity of changing the regulatory framework for predicting methane release and establishing the category hazard of mines by gas factor is substantiated, as well as the theoretical part of the research is experimentally confirmed and practical proposals are given to improve the requirements of regulatory documents for the safe mining of gas-bearing coal seams. The gas release from seven possible sources, the exposed surface of the working face, the undermined adjacent seams and their enclosing rocks, the overworked adjacent seams and enclosing rocks, the worked-out space of the stopped lavas, are accepted for consideration. The studies have shown that by removal the bottom from cut and the area of the mined-out space of the operated section and the wing of the mine field, taking into account the stopped longwalls, it is possible to predict the processes of rock displacement that determine the absolute gas release from the undermined sources.

scholarly journals Hydrodynamic impact on coal mass before crossing the most outburst-prone coal seams

2019 ◽  
Vol 109 ◽  
pp. 00112
Author(s):  
Vasyl Vlasenko ◽  
Dmytro Zhytlonok
Keyword(s):  
Coal Seam ◽  
Experimental Studies ◽  
Coal Mass ◽  
State Enterprise ◽  
Coal Seams ◽  
Dynamic Activity ◽  
Hydrodynamic Impact ◽  
Gas Dynamic ◽  
Mine Workings ◽  
Hydrodynamic Effects

The results of experimental studies of hydrodynamic effects (HDI) in industrial conditions are given. The HDI is designed to reduce the gas-dynamic activity of the coal seam and the rocks surrounding it. HDI was applied to the coal seam before it crossed the mine workings. The conditions for the implementation of HDI in industrial conditions Separate Enterprise “Mine “Tsentralna” State Enterprise “Toretskvuhillia” are described. The results of HDI on coal seams m2 -“Tonkyi” and m3 -“Tovstyi” are given. The parameters of the HDI method for outburst-prone coal seam before its crossing by mine workings are corrected.

Use of Destressing Drilling to Ensure Safety of Donbass Gas-bearing Coal Seams Extraction

2019 ◽  
pp. 7-11
Author(s):  
V.S. Brigida ◽  
◽  
Yu.V. Dmitrak ◽  
O.Z. Gabaraev ◽  
V.I. Golik ◽  
...  
Keyword(s):  
Coal Seams ◽  
Gas Bearing
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