煤层气地质选区评价方法研究

A RESEARCH ON THE METHOD OF GEOLOGICAL REGIONAL SELECTION EVALUATION OF COALBED GAS

在以往研究的基础上，对煤层气地质选区评价方法进行了研究。结果表明，煤层气地质选区评价的实质是要寻找富集、高渗、高压的含煤区。在煤层气地质选区方法方面除了要考虑煤层的基本性质（如煤层厚度、埋深、变质程度、含气量）外，更重要的是要研究煤层气高产富集的主控地质因素，如构造运动、沉积史、生烃史及三者间的关系，煤层上覆地层连续沉积厚度、瓦斯风化带、水文条件等方面对煤层气保存条件的影响；还要考虑古、今应力场对煤层渗透率的影响。这样才能搞清煤层气高产富集条件，指导煤层气地质选区评价研究。以大城地区、开平向斜及沁水盆地为例分析了煤层气保存条件并预测了煤储层高渗区，预测结果与实际试验吻合程度较高。

Through studying the method of geological regional selection evaluation of coalbed gas on the basis of the research finished by our predecessors,it is shown that the crux of the geological regional selection evaluation is to survey the enriched coalbearing area with high permeability and high pressure.During the geological regional selection of coalbed gas,besides considering the basic properties of the coalbed,as the thickness,burial depth,metamorphic grade and gas content of the coalbed,it is more important to study the principal geological factors of controlling high production and enrichment of the coalbed gas,such as the relation among tectonic movement,sedimentory history and hydrocarbon generation history,and the influence of the overlying strata's effective thickness,gas weathered zone and hydrogeological circumstances,etc.,on the preservation conditions of the coalbed gas,as well as the effect of the ancient and modern stress fields on coalbed permeability.Thus the conditions of controlling high production and enrichment of the coalbed gas can be found out so as to guide the research on the geologic regional selection evaluation of the coalbed gas.By taking the Dacheng district, Kaiping syncline and Qinshui Basin for examples,the preservation conditions of the coalbed gas are analyzed and the high permeability areas of the coal reservoir are predicted in the paper.The results of the evaluation and predication are highly corresponding to those of practical test.