Critical depth and accumulation characteristics of deep coalbed methane in the southern Ningwu Basin
In recent years,deep coalbed methane(CBM)has gradually become an important exploration and development field for oil and gas resources in China with continuous breakthroughs in deep CBM exploration and development technologies,but the basic scientific issues such as the scientific connotation of CBM depth limit,the geological characteristics of deep CBM reservoirs and the CBM enrichment patterns are still in the early exploration stage.Taking the No.9 coal seam of Taiyuan Formation in the Ningwunan Block of southern Ningwu Basin as the research object,this paper discusses the critical depth and accumulation characteristics of deep CBM in the Ningwunan Block based on drilling,logging and testing data of more than 20 CBM wells in this block,combined with isothermal adsorption and gas isotope experimental results.And the following research results are obtained.First,the critical depth of the deep CBM in the study area is 1 200 m,and the deep CBM reservoir below the critical depth is geologically characterized by great coal seam thickness,high degree of thermal evolution,high gas content,high gas saturation,good coal structure and low porosity.Second,geothermal gradient and thermal evolution degree are important factors influencing the critical depth and accumulation conditions of deep CBM in the study area.In conclusion,the geological characteristics of deep CBM in the Ningwunan Block of southern Ningwu Basin are comparable to those of deep CBM blocks in the Ordos Basin such as Daning-Jixian,Linxing,and Yanchuannan,indicating promising exploration and development prospects of deep CBM in the Ningwu Basin.
万方数据
维普
