Gas Occurrence Regularity And The Division Of Gas ?CBM? Extraction Of The B_11-2 In Mid-west Of Panxie Mine Area

The gas(CBM)occurrence is affected by many geological factors,and the output is a complex procedure composed of desorption,diffusion,filtration of gas and the exploration is geology-risk.It is necessary to make evaluation of the technical condition for extraction to extract the gas(CBM)effectively.The gas occurrence regularity of B11-2 is researched by using the gas geology theory in the mid-west of Panxie mine area,Huainan coalfield,Anhui Province and the extraction blocks are evaluated by using the fuzzy mathematical comprehensive evaluation.The impact on gas occurrence that the tectonic movement and evolution made is researched first in the text.Huainan coalfield was suffered from the near SN compressive stress in Indosinian-Yanshanian that lays the basic structural pattern of the area and the main structure Chenqiao anticline and the Panji anticline were formed in the middle of the coalfield,being near EW.The stratum was uplifted in Huainan coalfield with the continuous compress stress in Yanshanian,and it's denudated in the anticline axis and the outcrop was formed,which leads to the serious gas dissipation and makes an important impact on the gas occurrence.The NNE reverse faults were transformated into the normal ones formed in the earlier time in the surrounding of tensile stress in late Yanshanian,which promotes the gas dissipation further.The influence of the some factors on the gas occurrence in B11-2 coalseam is researched:coal metamorphic degree,coal seam thickness,surrounding rock,effective buried depth,geological structure,hydrogeology and the gas occurrence is mainly influenced by the geological structure.The gas content is high in the plunging anticline and the simple structure area where subsidiary anticline exists and low in the area where the NNE normal faults exist.Eleven gas geology units are divided mainly according to the geological structure,and the gas content,gas pressure are forcasted,and the gas resource amount is calculated.Seven extraction parameters are chosen according to the factors that influence the extraction and the parameters are:gas content,resource abundance,coal seam thickness,gas saturation,gas pressure gradient,coal structure and coal rank.And eight gas(CBM)extraction blocks are divided based on the geological units.The hierarchical structure model is established and the eight blocks are evaluated by using the fuzzy mathematical comprehensive evaluation,and the result shows that the block B4,Bl,B5,B8 are unfavorable,B7,B3 are less favorable,and B2,B6 are favorable according to the contrast:gB4<gB1<gB5<gB8<gB7<gB3<gB6<gB2.