岩浆热变质作用对临兴区块煤层气含量赋存影响

Impact on CBM Content Occurrence from Magmatic Thermal Metamorphism in Linxing Block

基于鄂尔多斯临兴区块的地质背景,分析了紫金山岩体的岩浆热变质作用及其对煤层气赋存的影响。燕山期是本区岩浆岩活动最强烈的地质时期,形成了紫金山岩体。靠近紫金山岩体,煤的变质程度快速升高,煤样镜质组最大反射率高达4.9%;围绕紫金山岩体,煤层的孔隙度、渗透率和煤层气含量呈现环带状展布特征,煤层气含量快速升高。研究认为:由叠加在深成变质作用基础上的岩浆热变质作用形成的高温烘烤作用下,岩浆热变质引起煤的二次生烃导致煤生气量增大和吸附性增强。

Based on geological setting of the Linxing block in Ordos basin, analyzed the Zijinshan rock mass magmatic thermal metamorphism and its impact on CBM hosting. The magmatic activities during the Yanshanian used to be the strongest in geological time in the area and formed Zijinshan rock mass. Near the rock mass, degree of coal metamorphism rapidly rising, the coal sample vitrinite maximum reflectance can be d. 9% as high. Around the rock mass, coal porosity, permeability and CBM content present girdle distri- bution features, and CBM content rising rapidly. The study has considered that under the high temperature baking of the magmatic thermal metamorphism and superimposed on the hypozonal metamorphism basis, magmatic thermal metamorphism has caused coal secondary hydrocarbon generation so as to coal -formed gas amount increasing and adsorptivity enhanced.