鄂尔多斯盆地东部临县-兴县地区山西组煤成气勘探潜力分析

Coal-derived gas exploration potential analysis of Shanxi Formation in Linxian-Xingxian County of eastern Ordos Basin

利用33口钻井的资料，对鄂尔多斯盆地东部山西省临县-兴县山西组岩石学特征、测井曲线特征进行了综合研究，划分了山西组沉积相及沉积微相，研究了主要储集砂体的空间展布，结合山西组聚煤特征及煤层厚度图，对煤成气勘探有利区域进行了预测。研究结果认为，临兴地区山西组煤层厚度大，分布稳定，干酪根类型为Ⅲ型，有机碳含量（TOC）70．8％-83．2％，有机质丰度较高，镜质体反射率尺。值在0．7％-1．5％之间，具有一定的生气潜力。山西组下部的山2^3段北岔沟砂岩砂体分布范围广，厚度大，有利于煤成气的储集，是煤成气勘探的最有利层位。通过对山西组沉积相、砂体厚度、煤层厚度及生烃能力等的综合研究，划分了Ⅰ类煤成气有利勘探区一个，Ⅱ类有利勘探区2个。

Comprehensive researches on the petrological characteristics and logging curves of 33 wells of Shanxi Formation in Linxing County, eastern part of the Ordos Basin, we identified sedimentary facies and microfacies of Shanxi Formation, and studied the spatial distribution of the main reservoir sand bodies. Based on coal accumulation characteristics and coal seam thickness map of Shanxi Formation, We forecasted the favorable area of coal-derived gas. The study results show that Shanxi Formation in Lin-xing area was the coal-derived gas potential area because of the big thickness and stable distribution of the coal seam, type Ⅲ kerogen, high total organic carbon content （ TOC ） （ range of 70. 8% 83.2% ）, high abundance of organic matter, and high vitrinite reflectance （Ro） values （0. 7% 1.5% ）. The Shan 23Beichagou sandstone of the lower Shanxi Formation was the most favorable reservoir of coal-derived gas exploration target for its wide sand body distribution, big thickness, which was benefi- cial to coal-derived gas reservoir. According to the comprehensive researches on the sedimentary facies, sand body thickness, seam thickness and hydrocarbon generation capacity of Shanxi formation, two types favorable exploration area of coal-derived gas was distinguished, i. e. class I and Ⅱ. There are one of Class Ⅰ favorable exploration area and two of Class Ⅱ.