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Test and Study on Surface Gas Drilling Technology from Boreholes in the Goaf
Hu Qianting1, 2, 3£¬Liang Yunpei1, 2£¬Lin Fujin3
£¨1. China University of Mining and Technology (Beijing), Beijing 100083£»2. Shandong University of Science and Technology, Qingdao, Shandong 266510£»3. Chongqing Branch, China Coal Research Institute, Chongqing 400037£©Abstract: Test results of surface gas extraction technology from boreholes in the goaf in Zhangbei Coal Mine, Huainan Mining Group are introduced in the paper. With the method of numerical simulation and site tests, the authors have made analysis on the law of gas emission and distribution in the goaf as well as optimized design of parameters and structure for surface borehole arrangements. Analysis on extraction results has been made based on site inspection tests. To some extent, the paper is of instructive significance for the research, promotion and application of gas extraction technology in the goaf.
Keywords: Surface borehole£»gas in the goaf£»gas extraction
Characteristics of CBM Enrichment in China
Wang Hongyan, Li Guizhong, Li Jingming, Liu Honglin and Wang Bo
£¨Exploration and Production Research Institute of Sinopec at Langfang, Hebei 065007£©Abstract: The study on CBM enrichment law runs through the whole process of CBM exploration, development and utilization, intimately related to coalfield geology, natural gas geology, fluid mechanics, etc. The main zones of CBM enrichment feature synclinal structure, and a great amount of study and practice confirms the synclinal mechanism of keeping stratum pressure naturally, CBM being easily enriched. The structural heat, on the one hand, causes the coal seam temperature to rise in a short time, the coal rank going high and CBM generated in a large amount, and, on the other hand, improves the properties of coal reservoir at the same time, which plays a big role in CBM enrichment. The effective thickness of the overlying stratum could be used to make a successful evaluation on the matching relationship between structural movement history, sedimentation history and hydrocarbon generation history. The hydrological geological condition is the main factor for CBM preservation and excess pressure formation.
Keywords: CBM; enrichment; factor
Study on Gas Extracting Technology of Gas Destressing and Gas Storage from Fractures in Surrounding Rock of Roof and Floor of the First-mined Seams
Liu Zegong1 and Yuan Liang2
(1. Anhui university of science and technology£¬Anhui Huainan 232001£»
2. Huainan Coal Mining Group Co.£¬Anhui Huainan 232001£©Abstract: In the process of first mining in soft high gassy seam groups with low permeability, fractures as well as big destressing and absorption of gas in working seams and adjacent relief seams occur with the collapse and movement of the strata of roof and floor. Destressing gas from large areas converges at the well-developed zones with fractures along the fracturing channel, which is within the O fracturing ring, forming the gas accumulating reservoir in the ring. The paper has discussed the method of locating the O ring, analyzed the process of gas accumulation in the ring and introduced arranging boreholes and tunnels in the O ring of the roof of the first-mined seams in order to employ the efficient gas extracting technology with better results.
Keywords£ºGas drainage£»coal seam£»annular fracture area
Analysis on Flow through Porous Media and Pressure Characteristics of Coalbed Methane
Li Tao1£¬He Ying-fu2 and Cao Lili3
(1. International Petroleum Exploration & Production Corporation SINOPEC£¬Beijing 100083£»2. Institute of Porous Flow and Fluid Mechanics£¬Chinese Academy of Sciences£¬Hebei Langfang 065007£»3.SINOPEC Petroleum Exploration & Production Institution£¬Beijing 100083)Abstract: There are two processes of dispersion and seepage when extracting CBM and its seepage process is more complicated than that in strata with regular natural gas. The study on the flow law of single-phase CBM in coal body and cleat has been made with the absorbing model in non-equivalent state. Under the assumption of mathematical model in the imitative stable flow and unstable flow, the pressure in the Langmuir Absorbing Formula is replaced with imitative gas pressure that has led to the equation with satisfied imitative pressure in the CBM strata. Analysis is also made on variable coefficients of permeability and the changing law of pressure with changes of parameters in double media. All these results have provided both the theory basis and new model for pilot wells to develop CBM resources.
Keywords: Coalbed methane£»percolation£»pressure performance analysis£»flow model
Study on Gas Geology in Tonghua Coalfield and Comprehensive Gas Control Measures
Xu Wenbo£¬Wang Shengyu and Chen Weiliang
£¨Tonghua Mining Bureau£¬Jilin 134300£©Abstract: Based on comprehensive analysis on gas content and emissions in seams and geological factors of Tonghua Mining Community, both the geological structure and the law of gas occurrence in seams are known well. Work on gas geology should be strengthened in order to give a forecast of gas emissions in in-depth mining sections of a working mine. Scientific gas control measures should be taken relying on advances of science and technology to ensure work safety in the mining community.
Keywords: Tonghua Coal Mining Area£»gas geology£»comprehensive control
Series Options of CBM Geophysical Logging
Zhou Shangzhong
£¨China United Coal Bed Methane Co., Ltd£¬Beijing 100011£©Abstract£ºThe principle, method and corresponding logging series are put forward in the paper according to physical properties of coal-bearing seams and logging response analysis. Methods of cementing and logging, evaluation on cementing quality and required duration of cementing and logging are also described in the paper.
Keywords£ºCBM£»logging response£»logging series
Study of Methane Adsorption on Coal with Adsorption Pontential Theory
Su Xianbo£¬Lin Meng£¬Lin Xiaoying and Chen Run
£¨Henan Polytechnic University£¬Henan Jiaozuo 454000£©Abstract£ºBased on the measured isotherm data under different temperature on the coal collected from Liulin coal district, the adsorption characteristic curve can be drawn and is described with an experimental equation in this paper. If one isotherm is measured, the coal adsorption capacity under any temperature and pressure can be calculated by using the characteristic curve and adsorption equation. This is an approach for the prediction of coalbed gas content under reservoir ambient. The adsorption theory can be successfully applied to describe the methane adsorption on coal, which is confirmed by the isotherm data measured on coal collected from Liulin, Qinshui Basin and Fuxin Basin.
Keywords£ºCoalbed methane£»adsorption potential theory£»adsorption characteristic curve£»reservoir ambient
The Analysis of Production Effect and the Discussion of Influencing Factors of Wucheng Coalbed Methane Test Well Group in Daning-Jixian Area
Wang Hongwei£¬Jiang Haoren£¬Ma Cailin and Quan Haiqi
£¨PetroChina Changqing Oilfield Company Research Institute of Exploration and Development£¬ShaanXi Xi¡¯an 710021£©Abstract£ºDaNing-Jixian area is endowed with rich coalbed methane resources, which mainly distributed in coal formation in Permo¡ªCarbeniferous. Coalbed Methane well group test has been carrying out from August 2004 to now in Wucheng town in DaNing-Jixian area. Based on synthetical calculation and analysis of production dynamic of test well group£¬the writer indicates that test well group is still in the position of single well production£¬which does not get the effect of interference between wells and well group production . Having analyzed related factors£¬on the further the writer presents some renovations in order to promote the next coalbed methane exploration.
Keywords£ºDaning-Jixian area£»coalbed methane well group£»production effect£»influencing factors
Understanding Gas Emission from Longwall Coalfaces
Julian Edwards
£¨University of Nottingham£¬UK£©Abstract: Authors of the paper have introduced the basic principle of in-seam gas release and movement, set forth the distribution of stress and fractures in longwall face, analyzed factors affecting gas extraction efficiency and drawn a comparison of gas extraction between two different mining methods in UK coal mines.
Keywords: Gas£»longwall face£»extraction
The Study on the Reservoir Characteristics of Low Rank Coal Seam in China
Fu Xiaokang1£¬Huo Yongzhong2£¬Chen Dong2 and Yang Xiuchun2
£¨1. China University of Geology Science£¬Beijing 100038£»2. China United Coalbed Methane Co. Ltd.£¬Beijing 100011£©Abstract£ºThe reservoir characters including the composition of the materials, the distribution and shapes of the pore, the adsorption and reservoir capabilities, permeability and irreducible water saturation of low rank coal in China are discussed through the analysis of the testing data of the low rank coal samples which are collected from Orders basin, Zhungeer Basin, Toha basin, Hailaer basin, Zhaotong basin. The research result will be favorable for the speeding up the CBM exploration in the Western low rank coal bearing area.
Keywords£ºCoalbed Methane£»Low rank coal£»Reservoir characteristics