煤层气勘探开发中的煤储层评价

RESERVOIR EVALUATION FOR EXPLORATION AND DEVELOPMENT OF COAL-BED GAS

煤储层评价参数的获取可以大致分为宏观煤储层、煤岩类型、普通显微镜下测试和电镜等超显微孔隙测试四个层次。煤层气井煤心和煤储层露头的煤岩类型系统测量是获取煤储层评价参数的关键环节。建立煤储层描述参数与规范 ,积累系统的煤储层评价资料 ,以满足煤层气勘探开发的需要。煤储层评价的重点内容包括煤体几何形态与内部结构特征、煤储层顶板和底板岩石与裂隙发育特征、煤储层孔裂隙系统发育特征和煤储层渗透率、煤岩组成和煤质特征、煤的机械力学性质、煤层气的解吸特征、煤储层的可改造性 ,以及煤变质作用类型和煤级分带特征等。煤储层评价的基本原则包括乘积原则、加权平均原则、“木桶效应”原则。

The parameters to evaluate coal reservoirs can be obtained from the 4 levels,i.e. macroscopic observation of coal reservoirs and coal rocks,surveying under common microscope,and surveying of super-microscopic pores under electronic microscope. The key link to obtain the evaluation parameters of coal reservoirs is the coal cores from coal-bed gas wells and the coal rock from coal reservoir outcrop. It is necessary to establish parameters and principles of coal reservoir description,and gather systemic data of coal reservoir evaluation for meeting the requirements of exploration and development for coal-bed gas. The major contents of coal reservoir evaluation as follows: the geometry of coal body and its structure,the features of the top-rock and bottom-rock and the fracture growing of the coal reservoir,the pore-fracture system growing features and the permeability of the coal reservoir,the litho-types and maceral of the coal,the mechanics property of the coal,the de-sorption characteristics of the coal-bed gas,the modifiable property of the coal reservoir,the metamorphosis type of the coal,and the distribution feature of the coal rank,etc. The basic principles of coal reservoir evaluation include the parameters multiplication,the weighted mean,the“wood barrel effect”,the analogy evaluation,and the comprehensive evaluation.