scholarly journals Analysis of Gas Content and Permeability Change Pattern of a Coal Reservoir in the Tectonic Positions Based on a THM Coupled Model

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Zhenni Ye ◽  
Enke Hou ◽  
Huantong Li ◽  
Zhonghui Duan ◽  
Fan Wu
Keyword(s):  
Coal Seam ◽  
Fault Plane ◽  
Normal Fault ◽  
Geological Structure ◽  
Gas Content ◽  
High Permeability ◽  
Reservoir Permeability ◽  
Variation Distance ◽  
Hinge Zone ◽  
Coal Reservoir

The theory of coalbed methane distribution controlled by tectonism is a hot issue in the field of geofluid-geotectonic interaction research. Taking the geological structure in the scale range of the 1302 working face of a Guojiahe wellfield in a Yonglong mining area as the background, this paper focuses on the basic research problem of the influence of geological structure on the control of coal reservoir gas content and uses a THM coupling model to analyze the change of coalbed gas content and distribution characteristics of different tectonic positions. The change of CBM content and permeability in the anticline, syncline, and faults is analyzed. Accordingly, the variation distance of gas content and reservoir permeability controlled by tectonism of different geological structures is quantified to provide guidance for the selection of CBM-favorable areas. The research results show that the gentle dip syncline hinge zone is a potential gas-rich area with heat preservation and low permeability, while the gentle dip anticline hinge zone is a gas-poor area with low temperature and low pressure and high permeability. The thick coal seam zone of the syncline hinge zone is the potential gas accumulation zone, and the high-permeability area is near the fault plane of a normal fault. The coal matrix near the normal fault is subjected to tensile tectonic stresses to form tensional fissures, and the coal seam in the fault plane area is susceptible to coalbed gas dispersion and increases the permeability of the coal reservoir. The variation distance of gas content and reservoir permeability controlled by the normal fault within the Guojiahe wellfield is 37 m and 54 m from the fault plane, respectively.

scholarly journals Multi-Phase Tectonic Movements and Their Controls on Coalbed Methane: A Case Study of No. 9 Coal Seam from Eastern Yunnan, SW China

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6003
Author(s):  
Ming Li ◽  
Bo Jiang ◽  
Qi Miao ◽  
Geoff Wang ◽  
Zhenjiang You ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Normal Fault ◽  
Geological Structure ◽  
Local Deformation ◽  
Gas Content ◽  
Reverse Fault ◽  
Geological Structures ◽  
Dextral Shear ◽  
Multi Phase ◽  
Tectonic Movements

Multi-phase tectonic movements and complex geological structures limit the exploration and hotspot prediction of coalbed methane (CBM) in structurally complex areas. This scientific problem is still not fully understood, particularly in the Bumu region, Southwest China. The present paper analyses the occurrence characteristics and distribution of CBM based on the comprehensive analysis of CBM data. In combination with the analysis of the regional tectonics setting, geological structure features and tectonic evolution. The control action of multi-phase tectonic movements on CBM occurrence are further discussed. Results show that the Indosinian local deformation, Yanshanian intense deformation, and Himalayan secondary derived deformation formed the current tectonic framework of Enhong synclinorium. The intense tectonic compression and dextral shear action in the Yanshanian and Himalayan movements caused the complex geological structures in Bumu region, composed of the Enhong syncline, associated reverse faults and late derived normal fault. The CBM distribution is complex, which has the central and western NNE-trending high gas content zones along the syncline hinge zone and the reverse faults. The geological structure controls on CBM enrichment are definite and important. Based on geological structure features and responses of gas content, methane concentration, and gas content gradient, the gas controlling patterns of geological structure are determined and can be classified into five types: the reverse fault sealing, syncline sealing, monoclinal enrichment, normal fault dispersion, and buried floor fault dispersion types. The structural compression above the neutral surface plays an important role in the syncline sealing process, which is indicated by an increase in gas content gradient. The EW-trending tectonic intense compression and dextral shear action in the Himalayan movement avoided the negative inversion of NNE-trending Yanshanian compressive structure and its destruction of CBM reservoir. However, the chronic uplift and derived normal fault during Himalayan period caused the constant dissipation of CBM.

scholarly journals Investigation on coal seam distribution and gas occurrence law in Guizhou, China

2018 ◽  
Vol 36 (5) ◽  
pp. 1310-1334 ◽  
Author(s):  
Qingsong Li ◽  
Xin He ◽  
Jiahao Wu ◽  
Shu Ma
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Sedimentary Environment ◽  
Influence Factors ◽  
Preventive Treatment ◽  
Geological Structure ◽  
Mine Safety ◽  
Gas Content ◽  
Gas Occurrence ◽  
Safety Production

In order to enhance the management level of coal mine safety production and promote the “safe, accurate and efficient” preventive treatments for gas in Guizhou of China, the occurrence and other prominent features of coal and gas are investigated. The characteristics and regularities of coal mine accidents in Guizhou during 2001–2015 are summarized to analyze the commonness of gas accidents in general and determine the characteristics of gas preventive treatment. Geological data, gas basic parameters, and physical properties of coal of 386 mines and 761 sets of coal seams in Guizhou are also statistically analyzed. Based on step control theory of gas occurrence structure and the regionally tectonic regularity of coal-bearing stratum distribution, the deformations of coal measures in Guizhou mine area are mainly caused by great variation of stratigraphic occurrence, complicated geological structure, and high crustal stress. The regional occurrence of coal seam is obvious with the highest content of Tongzi–Zunyi–Liuzhi–Xingyi line, which gradually reduces to the both east and west sides. Influence factors and weights of gas occurrence are expounded from geological and coal factor by mathematical statistics, and the main influence factors of gas occurrence are the sedimentary environment, syncline structure, and metamorphic grade in proper sequence. Combined with the risk prediction of coal and gas outburst area, the prediction of gas pressure by gas content is not suitable under the special occurrence conditions. The initial velocity of gas emission, the solidity coefficient, and the damage type in more than 77% of minable seams all exceed the critical value. This work provides guidance in improvement of the governance situation for gas control in Guizhou. The index prediction system which is suitable for mining conditions of special coal mines in Guizhou should be established.

Gas Geology Law and Gas Forecast in Yongju Well Field

2011 ◽  
Vol 361-363 ◽  
pp. 208-211
Author(s):  
Cui Jia ◽  
Yu Lin Wang ◽  
Xu Yang ◽  
Mi Shan Zhong ◽  
Nan Yan
Keyword(s):  
Coal Seam ◽  
Geological Structure ◽  
Measured Data ◽  
Gas Content ◽  
Coal Seam Gas ◽  
Production Safety ◽  
Geological Conditions ◽  
Well Field ◽  
Gas Occurrence ◽  
The Relationship

This paper takes gas as a geological-mass to study, using gas geology theory, by analysising the geological conditions of Yongju mine in ShanXi, combining with the coal seam gas content data which measured underground to study the relationship between geological conditions and gas occurrence, reveal the gas occurrence factors: geological structure, roof and floor lithologic of coal seam, buried depth of coal seam and thickness of coal seam. Finally, using the measured data of gas content and gush, regression analysis, the gas gush is forecasted, playing a guiding role in the gas control and production safety .

scholarly journals A research on the influence of geological factors to gas discharge from No.8 un-mined solid coal seam of Baode Coal Mine

2021 ◽  
Vol 284 ◽  
pp. 01016
Author(s):  
Yinghua Lv ◽  
Shi Gang An ◽  
Wen Xu Liang ◽  
Dian Fu Chen ◽  
Wei Fu
Keyword(s):  
Coal Seam ◽  
Coal Mine ◽  
Research Result ◽  
Geological Structure ◽  
Relational Model ◽  
Gas Content ◽  
Solid Coal ◽  
Gas Occurrence ◽  
Geological Factors ◽  
Grey Relational

Mining is gradually progressed toward the in-depth area of No.8 solid coal seam in No.3 panel of Baode Coal Mine. In order to secure safe mining in this area, a systematic analysis is conducted on the geological factors that influence gas occurrence. Based on the basic data actually measured at site, grey relational analysis (GRA) is adopted for predictive analysis of influencing factors (depth, coal seam thickness, metamorphic grade, sand to mud ratio of roof, sand to mud ratio of floor, geological structure and washout), followed by establishment of a grey relational model. Then, the relation degree among factors is calculated, thus identifying the main controlling factors of gas occurrence. The research result suggests: the main geological factors that influence gas occurrence in No.8 coal seam are geological structure and washout. A model equation is established for prediction of gas content using multiple regression method: y=3.2429+0.0047X1+0.0079X2-0.0180X3+0.0016X4-0.0215X5+0.4641X6+0.2001X7. This equation demonstrates high degree of fitting.

COAL SEAM GAS IN THE SOUTHERN SYDNEY BASIN, NEW SOUTH WALES

1997 ◽  
Vol 37 (1) ◽  
pp. 415 ◽  
Author(s):  
M.M. Faiz ◽  
A.C. Hutton
Keyword(s):  
Coal Seam ◽  
New South ◽  
Geological Structure ◽  
Gas Content ◽  
Gas Composition ◽  
Late Permian ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
South Wales ◽  
Coal Measures

The coal seam gas content of the Late Permian Illawarra Coal Measures ranges from Methane that occurs within the basin was mainly derived as a by-product of coalification. Most of the CO2 was derived from intermittent magmatic activity between the Triassic and the Tertiary. This gas has subsequently migrated, mainly in solution, towards structural highs and accumulated in anticlines and near sealed faults.The total desorbable gas content of the coal seams is mainly related to depth, gas composition and geological structure. At depths

scholarly journals Gas Content Evaluation of Coalbed Methane Reservoir in the Fukang Area of Southern Junggar Basin, Northwest China by Multiple Geophysical Logging Methods

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1867 ◽  
Author(s):  
Xu Ge ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Yingjin Wang
Keyword(s):  
Coalbed Methane ◽  
Normal Fault ◽  
Junggar Basin ◽  
Analysis Data ◽  
Northwest China ◽  
Geological Structure ◽  
Gas Content ◽  
Burial Depth ◽  
Reverse Fault ◽  
Geophysical Logging

To study the gas potential of coalbed methane (CBM) in the Fukang area, southern Junggar Basin (SJB) of North China, different methods including multiple geophysical logging, the Kim method with proximate analysis data, and Langmuir adsorption were used to evaluate the gas content. Furthermore, the geological controls on gas content were evaluated. One hundred sixteen CBM wells with geophysical logging and 20 with field-measured gas content were adopted to assess the gas content in the Fukang area of SJB, NW China. The results show that the two geophysical logging variables (DEN and CNL) were favorable for evaluating the gas content due to the perfect correlation with the measured gas content. The gas content varies from 4.22 m3/t to 16.26 m3/t, and generally increases with increasing burial depth. The gas content in coal seams along the synclinal axis is significantly higher than that along the synclinal wing in the west zone. In the east zone, the gas content of the westward is higher than that of the eastward because of the fault coating effect by reverse fault. Generally, the gas content of the SJB is in the order of syncline > surrounding reverse fault > slope of syncline > slope of anticline > central of reverse fault, if only geological structure features are considered. The favorable areas for CBM concentration appear to be a composite gas controlling result of multiple geological factors. Two typical geological scenarios with low gas content and high gas content were revealed. In the Fukang area of SJB, the low gas content is mainly due to the normal fault and roof lithology of sandstone. The most favorable area of high gas content for CBM exploration and development is in the northeast, where reversed fault, synclinal axis, mudstone roof lithology, and burial depth coincide with high gas content.

Analysis on Gas Geological Law of No.56 Coal Seam in Shengli Mine

2013 ◽  
Vol 295-298 ◽  
pp. 2859-2863
Author(s):  
Yong Li Liu ◽  
Yuan Ping Ma ◽  
Tao Qin ◽  
Chang Ji Dong
Keyword(s):  
Coal Seam ◽  
Geological Structure ◽  
Gas Content ◽  
Structure Evolution ◽  
Geologic Structure ◽  
Gas Emission ◽  
Fault Fracture Zone ◽  
Gas Occurrence ◽  
Abnormal Phenomenon ◽  
Mine Gas

Based on the analysis of geologic structure evolution and distribution characteristic in the Shengli Mine, which studied the influence that the mine geological structure, roof and floor lithologic of coal seam and elevation of seam floor, made on mine gas occurrence, combined with geological data and a large number of experimental data. Detailed elaboration about the situation in the Shengli Mine gas geology law, and prediction about gas emission and the dangerous of gas regional outburst. The results show that the gas content of the seam would be increases with the depth of the seam increases; There would be an abnormal phenomenon occurred at the geological fault about the gas occurrence, which is especially obvious in fault fracture zone.

scholarly journals A Comprehensive Coal Reservoir Classification Method Base on Permeability Dynamic Change and Its Application

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 644 ◽  
Author(s):  
Xinlu Yan ◽  
Songhang Zhang ◽  
Shuheng Tang ◽  
Zhongcheng Li ◽  
Yongxiang Yi ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Dynamic Change ◽  
Initial Permeability ◽  
Gas Production ◽  
Gas Desorption ◽  
Reservoir Permeability ◽  
Geological Conditions ◽  
Production Stages ◽  
Productivity Potential ◽  
Coal Reservoir

Due to the unique adsorption and desorption characteristics of coal, coal reservoir permeability changes dynamically during coalbed methane (CBM) development. Coal reservoirs can be classified using a permeability dynamic characterization in different production stages. In the single-phase water flow stage, four demarcating pressures are defined based on the damage from the effective stress on reservoir permeability. Coal reservoirs are classified into vulnerable, alleviative, and invulnerable reservoirs. In the gas desorption stage, two demarcating pressures are used to quantitatively characterize the recovery properties of permeability based on the recovery effect of the matrix shrinkage on permeability, namely the rebound pressure (the pressure corresponding to the lowest permeability) and recovery pressure (the pressure when permeability returns to initial permeability). Coal reservoirs are further classified into recoverable and unrecoverable reservoirs. The physical properties and influencing factors of these demarcating pressures are analyzed. Twenty-six wells from the Shizhuangnan Block in the southern Qinshui Basin of China were examined as a case study, showing that there is a significant correspondence between coal reservoir types and CBM well gas production. This study is helpful for identifying geological conditions of coal reservoirs as well as the productivity potential of CBM wells.

REAL-TIME 2.5D INVERSION OF LWD RESISTIVITY MEASUREMENTS USING DEEP LEARNING FOR GEOSTEERING APPLICATIONS ACROSS FAULTED FORMATIONS

2021 ◽  
Author(s):  
Kyubo Noh ◽  
◽  
Carlos Torres-Verdín ◽  
David Pardo ◽  
◽  
...  
Keyword(s):  
Deep Learning ◽  
Real Time ◽  
Fault Plane ◽  
Synthetic Data ◽  
Field Measurements ◽  
Geological Structure ◽  
Inversion Method ◽  
Adaptive Finite Element ◽  
Resistivity Measurements ◽  
Lwd Resistivity

We develop a Deep Learning (DL) inversion method for the interpretation of 2.5-dimensional (2.5D) borehole resistivity measurements that requires negligible online computational costs. The method is successfully verified with the inversion of triaxial LWD resistivity measurements acquired across faulted and anisotropic formations. Our DL inversion workflow employs four independent DL architectures. The first one identifies the type of geological structure among several predefined types. Subsequently, the second, third, and fourth architectures estimate the corresponding spatial resistivity distributions that are parameterized (1) without the crossings of bed boundaries or fault plane, (2) with the crossing of a bed boundary but without the crossing of a fault plane, and (3) with the crossing of the fault plane, respectively. Each DL architecture employs convolutional layers and is trained with synthetic data obtained from an accurate high-order, mesh-adaptive finite-element forward numerical simulator. Numerical results confirm the importance of using multi-component resistivity measurements -specifically cross-coupling resistivity components- for the successful reconstruction of 2.5D resistivity distributions adjacent to the well trajectory. The feasibility and effectiveness of the developed inversion workflow is assessed with two synthetic examples inspired by actual field measurements. Results confirm that the proposed DL method successfully reconstructs 2.5D resistivity distributions, location and dip angles of bed boundaries, and the location of the fault plane, and is therefore reliable for real-time well geosteering applications.

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