scholarly journals Study on Reservoir Properties and Critical Depth in Deep Coal Seams in Qinshui Basin, China

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Guiqiang Zheng ◽  
Bin Sun ◽  
Dawei Lv ◽  
Zhejun Pan ◽  
Huiqing Lian
Keyword(s):  
Coal Seam ◽  
Step Change ◽  
Gas Content ◽  
Burial Depth ◽  
Critical Depth ◽  
Coal Seams ◽  
Reservoir Properties ◽  
Qinshui Basin ◽  
Geological Conditions ◽  
Change Characteristics

Coalbed methane (CBM) reservoir properties and relationship of properties with burial depth were studied based on the data derived from 204 deep CBM production wells in Qinshui Basin, China. Through the study, it is found that permeability and porosity decrease with the increase of burial depth and the decreasing trend shows step-change characteristics at a critical burial depth. They also show divisional characteristics at certain burial depth. Gas content, geostress, and geotemperature increase with the increase of burial depth, and the increasing trend shows step-change characteristics and also have divisional characteristics at certain burial depth. Based on the previous study on the reservoir property changes with burial depth, three series of critical depth using different parameters are obtained through simulating the critical depth using the BP neural network method. It is found that the critical depth is different when using different parameters. Combined the previous study with the normalization of three different parameter types, the critical depth in Qinshui Basin was defined as shallow coal seam is lower than 650 m and transition band is 650–1000 m, while deep coal seam is deeper than 1000 m. In deep coal seams, the geological conditions and recovery becomes poor, so it can be defined as unfavorable zones. Therefore, other development means, for example, CO2 injection, need to be used to accelerate the deep coal methane development.

Geological Characteristics of Coalbed Methane Reservoir in Southern Shizhuang Block, Southeastern Qinshui Basin

2013 ◽  
Vol 295-298 ◽  
pp. 3209-3212
Author(s):  
Li Ren Xing ◽  
Yan Bin Yao ◽  
Da Meng Liu ◽  
Jun Gang Liu ◽  
Lu Lu Zhou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Local Structure ◽  
Coalbed Methane ◽  
Simple Structure ◽  
Gas Content ◽  
Burial Depth ◽  
Coal Seams ◽  
Structure Characteristics ◽  
Geological Characteristics ◽  
Coalbed Methane Reservoir

Southern Shizhuang Block has simple structure characteristics, relatively thick coal seams (3.1-10.5 m, 6 m in average), and favorable burial depth (450-900 m). The gas content of the No.3 coal seam in the Shanxi formation ranges from 6-20 m3/t, and it increases from the southeast to northwest area in the southern Shizhuang Block. Gas content is high in the structural low in the area, which means the gas accumulation is controlled by the geological characteristics of local structure and hydrogeologic conditions.

Comprehensive Analysis of Factors Affecting Coalbed Methane Productivity: A Case Study of Southern Qinshui Basin

2014 ◽  
Vol 962-965 ◽  
pp. 21-28
Author(s):  
Bei Liu ◽  
Wei Hua Ao ◽  
Wen Hui Huang ◽  
Qi Lu Xu ◽  
Juan Teng
Keyword(s):  
Coalbed Methane ◽  
Gas Production ◽  
Gas Content ◽  
Burial Depth ◽  
Reservoir Pressure ◽  
Factors Affecting ◽  
Qinshui Basin ◽  
Geological Conditions ◽  
Geological Factors ◽  
Southern Qinshui Basin

Coalbed methane (CBM) productivity is influenced by various factors. Based on field production data and test data of southern Qinshui Basin, factors including geological factors, engineering factors and drainage factors that affect CBM productivity are analyzed. Analytic hierarchy process (AHP) is introduced to calculate the contribution of each parameter to CBM productivity. A three-level model for evaluating CBM productivity based on AHP is established. The results show that average daily gas production of single well in southern Qinshui Basin increases with gas content, coal seam thickness, permeability, porosity, gas saturation, critical desorption pressure. Filling minerals in pores and fractures of coal can decrease gas content, porosity and permeability of coal reservoir. When burial depth is deeper than 500m or reservoir pressure is greater than 2MPa and burial depth is shallower than 1000m or reservoir pressure is less than 10MPa, CBM productivity is relatively high. According to the calculation, the weight of geological factors, engineering factors and drainage factors are 50%, 25% and 25%, respectively. Reservoir physical properties, geological conditions, fracturing technology and drainage process have the most impact, the weight of which are 33.33%, 16.67%, 11.79%, and 15.00%, respectively.

scholarly journals Geological Factors and Reservoir Properties Affecting the Gas Content of Coal Seams in the Gujiao Area, Northwest Qinshui Basin, China

Energies ◽  
2018 ◽  
Vol 11 (5) ◽  
pp. 1044 ◽  
Author(s):  
Zhuo Zou ◽  
Dameng Liu ◽  
Yidong Cai ◽  
Yingjin Wang ◽  
Jiapeng Li
Keyword(s):  
Gas Content ◽  
Coal Seams ◽  
Reservoir Properties ◽  
Qinshui Basin ◽  
Geological Factors

Accumulation Conditions and Gas Content Characteristics of the Lower Silurian in Northwestern Hunan, China

2013 ◽  
Vol 868 ◽  
pp. 192-195
Author(s):  
Tuo Lin ◽  
Jin Chuan Zhang ◽  
Bo Li ◽  
Wei He ◽  
Xuan Tang
Keyword(s):  
Black Shale ◽  
Sedimentary Environment ◽  
Sedimentary Facies ◽  
Black Shales ◽  
Gas Content ◽  
Burial Depth ◽  
Reservoir Properties ◽  
Isothermal Adsorption ◽  
Lower Silurian ◽  
Deposition Conditions

The Lower Silurian marine shale is widely distributed in Northwestern Hunan and features in a large thickness of dark shale showed at outcrops. However, the accumulation conditions and gas content is unknown. The sedimentary facies, thickness and distribution, organic matter types and content, maturity, reservoir properties and gas content of the Lower Silurian black shale in Northwestern Hunan were investigated by field observation, sampling and experimental analysis. The results show that the black shales sedimentary environment is deep water continental shelf, with featured in abundant fossil. The burial depth of the Lower Silurian black shale is 0-3000 m, and its thickness is 10-40m while the average TOC is 1.0% and average Ro is 2.9%. For the disadvantaged sedimentary facies and shallow depth, the maximum gas content of the Lower Silurian black shale from well site desorption test is 0.59m3/t only, but the result of isothermal adsorption simulate test show that the Lower Silurian black shale have a good adsorption capacity, and can generate a large number of shale gas in Northwestern Hunan where better deposition conditions and suitable depth exist in.

scholarly journals Investigation of Hydraulic Fracturing Crack Propagation Behavior in Multi-Layered Coal Seams

2020 ◽  
Vol 10 (3) ◽  
pp. 1153 ◽  
Author(s):  
Shirong Cao ◽  
Xiyuan Li ◽  
Zhe Zhou ◽  
Yingwei Wang ◽  
Hong Ding
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Crack Propagation ◽  
Principal Stress ◽  
Fracture Propagation ◽  
Clean Energy ◽  
Burial Depth ◽  
Coal Seams ◽  
Initiation Pressure ◽  
Dip Angle

Coalbed methane is not only a clean energy source, but also a major problem affecting the efficient production of coal mines. Hydraulic fracturing is an effective technology for enhancing the coal seam permeability to achieve the efficient extraction of methane. This study investigated the effect of a coal seam reservoir’s geological factors on the initiation pressure and fracture propagation. Through theoretical analysis, a multi-layered coal seam initiation pressure calculation model was established based on the broken failure criterion of maximum tensile stress theory. Laboratory experiments were carried out to investigate the effects of the coal seam stress and coal seam dip angle on the crack initiation pressure and fracture propagation. The results reveal that the multi-layered coal seam hydraulic fracturing initiation pressure did not change with the coal seam inclination when the burial depth was the same. When the dip angle was the same, the initiation pressure linearly increased with the reservoir depth. A three-dimensional model was established to simulate the actual hydraulic fracturing crack propagation in multi-layered coal seams. The results reveal that the hydraulic crack propagated along the direction of the maximum principal stress and opened in the direction of the minimum principal stress. As the burial depth of the reservoir increased, the width of the hydraulic crack also increased. This study can provide the theoretical foundation for the effective implementation of hydraulic fracturing in multi-layered coal seams.

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 Nitrogen Injection To Flush Coal Seam Gas Out Of Coal: An Experimental Study

2015 ◽  
Vol 60 (4) ◽  
pp. 1013-1028 ◽  
Author(s):  
Lei Zhang ◽  
Naj Aziz ◽  
Ting Ren ◽  
Jan Nemcik ◽  
Shihao Tu
Keyword(s):  
Coal Seam ◽  
Clean Energy ◽  
Gas Content ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Gas Recovery ◽  
Nitrogen Injection ◽  
Gas Desorption ◽  
Effective Role ◽  
Study Laboratory

Abstract Several mines operating in the Bulli seam of the Sydney Basin in NSW, Australia are experiencing difficulties in reducing gas content within the available drainage lead time in various sections of the coal deposit. Increased density of drainage boreholes has proven to be ineffective, particularly in sections of the coal seam rich in CO2. Plus with the increasing worldwide concern on green house gas reduction and clean energy utilisation, significant attention is paid to develop a more practical and economical method of enhancing the gas recovery from coal seams. A technology based on N2 injection was proposed to flush the Coal Seam Gas (CSG) out of coal and enhance the gas drainage process. In this study, laboratory tests on CO2 and CH4 gas recovery from coal by N2 injection are described and results show that N2 flushing has a significant impact on the CO2 and CH4 desorption and removal from coal. During the flushing stage, it was found that N2 flushing plays a more effective role in reducing adsorbed CH4 than CO2. Comparatively, during the desorption stage, the study shows gas desorption after N2 flushing plays a more effective role in reducing adsorbed CO2 than CH4.

Important Factors to Propose High-Produced New Development Wells in CBM Project

2014 ◽  
Vol 1030-1032 ◽  
pp. 2578-2581
Author(s):  
Zhao Hui Xia ◽  
Ming Zhang ◽  
Bin Ren ◽  
Liang Chao Qu ◽  
Ze Hong Cui ◽  
...  
Keyword(s):  
Coal Seam ◽  
3D Model ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Coal Seams ◽  
Reservoir Properties ◽  
Well Design ◽  
New Development ◽  
Reservoir Type ◽  
High Production

Coal bed methane (CBM) is a kind of natural gas that generated from coal and disseminated organic matters during the stage of diagenesis and coalification, which mainly composed of methane and hosted in coal seam by free, adsorbed, and dissolved forms. Genetic, reservoir type and occurrence condition in CBM are different from traditional reservoir. And the high-produced development wells in CBM aiming to drill more coal seams with high quality therefore needs to be analyzed in the methods that are different from traditional reservoir. 3 important factors including the study on correlation and elevation depth of coal seam roof and floor in section and areal by using well-seismic ties, outcrop boundary based on coal mine data and distributions of CBM reservoir properties in 3D model are needed for high-produced development well analyze in CBM. Application in Australia CBM project shows this methodology is very successful for the development well design with high production.

Prediction Technology of Coal and Gas Outburst in Xuandong Coal Mine

2011 ◽  
Vol 255-260 ◽  
pp. 3731-3734
Author(s):  
Sheng Shan Zhao ◽  
Wei Dong Pan ◽  
Xin Wang ◽  
Jia Dun Liu
Keyword(s):  
Coal Mine ◽  
Magmatic Rock ◽  
Coal And Gas Outburst ◽  
Gas Content ◽  
Burial Depth ◽  
Disaster Reduction ◽  
Geological Structures ◽  
Practical Situation ◽  
Gas Outburst ◽  
Geological Conditions

Based on the complicated geological conditions of coal seam in Xuandong Coal Mine, such as deep burial depth, high gas content, magmatic rock intrusion and so on, the distribution regularities of magmatic rock, gas and geological structures were analyzed and studied. Combining with the practical situation of the dynamic disaster and phenomenon during the mining, the dangerous zones of coal and gas outburst were predicted and regional divided. The research results would have certain significance of practical guide to the outburst prevention and disaster reduction.

scholarly journals Relation between basic coal seam parameters and their gas saturation for Dobrudzha coal field, NE Bulgaria

2021 ◽  
Vol 280 ◽  
pp. 08006
Author(s):  
Nikolay Hristov ◽  
Efrosima Zaneva-Dobranova ◽  
Gergana Meracheva ◽  
Viktoriia Dmytrenko ◽  
Yuriy Vynnykov
Keyword(s):  
Coal Seam ◽  
Energy Resource ◽  
Point Of View ◽  
Coal Seams ◽  
Gas Saturation ◽  
The North ◽  
Geological Conditions ◽  
Petrophysical Model ◽  
Basic Parameters ◽  
Size And Morphology

One of the main natural gas contained in the coal seams is methane. Most of it is adsorbed on the surface of the coal matrix, another is in free state in different in size and morphology pore spaces or dissolved gas in the waters that associate with the coal seams. The form of presence and the degree of gas saturation depends on the rank of the carbonization process, the petrophysical and physicochemical parameters of the environment. Methane in coal seams is accepted to be categorized as an unconventional energy resource. From this point of view, it is of interest in the Dobrudzha coal basin, located in the North-eastern part of Bulgaria. The specific geological conditions of the basin, the limited study, the presence of a thick covering aquifer make it difficult to extract coal by traditional methods. This requires the use of non-popular for the country methods for energy extraction and establishing relation between the basic parameters of coal seams and their gas saturation. The existing geological-geophysical, drilling and laboratory information is combined in a detailed petrophysical model, which extends over the best presented and studied coal seam (m5) from the field. The basic parameters that reflect the amount of adsorbed gas and are the subject of study are the content of moisture, carbon, ash and the degree of carbonization, expressed by the vitrinite and its reflectance.

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