滇东北石坎矿区煤层气储层特征研究及控气地质因素分析

Research on CBM reservoir features and geology factors of gas-controlling analysis of Shikan mining area,Northeast Yunnan Province

滇东北石坎矿区赋存丰富的煤层气资源,针对研究区C5煤层煤岩煤质特征、物性特征、煤层吸附—解吸特性、含气量分布特征、煤层气富集的控制因素等进行了分析研究。结果表明,石坎矿区C5煤层厚度为0.25~4.93 m,平均厚2.48 m,分布稳定,且构造变形程度相对较弱,有利于煤层气的后期开发;所测得的兰氏体积为21.29~30.24 m^(3)/t,平均26.20 m^(3)/t,反映出煤层吸附性强;煤储层试井渗透率为0.024×10^(-3)~0.180×10^(-3)μm^(2),平均为0.087×10^(-3)μm^(2),属中低渗储层;煤层储层压力为2.81~6.55 MPa,平均为4.65 MPa,总体上储层压力均较高,地层能量较好。C5煤层实测含气量为2.45~21.78 m^(3)/t,平均11.05 m^(3)/t,含气量较高。通过对各控气要素的分析,认为埋深和局部的封闭性构造是控制含气量高低的主要因素,优选了2个有利区,为下一步煤层气勘查工作寻找有利区提供了地质依据。

The Shikan mining area in northeast Yunnan is endowed with rich CBM resources.The coal quality characteristics,physical characteristics,adsorption-desorption characteristics,gas content distribution characteristics,and control factors of CBM enrichment of the C 5 coal seam in the study area were analyzed and researched.The results show that the thickness of C 5 coal seam in Shikan mining area ranges from 0.25 m to 4.93 m,with an average thickness of 2.48 m,with stable distribution and relatively weak tectonic deformation,which is favorable for the later development of CBM;the measured Langstroth volume ranges from^(2)1.29 m^(3)/t to 30.24 m^(3)/t,with an average of 26.20 m^(3)/t,which reflects the strong adsorption of the coal seam;the permeability of the coal reservoir in the test wells is 0.024×10^(-3)-0.180×10^(-3)μm^(2),with an average of 0.087×10^(-3)μm^(2),belongs to the middle and low permeability reservoir;the reservoir pressure of the coal seam is between 2.81 MPa and 6.55 MPa,with an average of 4.65 MPa,the overall reservoir pressure is higher,and the energy of the formation is better.The measured gas content of the C 5 coal seam is between 2.45 m^(3)/t and 21.78 m^(3)/t,with an average of 11.05 m^(3)/t,and the gas content is higher.Through the analysis of each gas-controlling element,it is believed that the depth of burial and local closed structure are the main factors controlling the gas content,and two favorable zones are preferred,which can provide geological basis for the next step of finding favorable zones for CBM exploration work.