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鄂尔多斯盆地东南部延长区天然气勘探程度低,对该区古地理格局、沉积相类型及展布特征、储集层岩石特点及其储集条件进行分析,进而预测该区上古生界山西组、下石盒子组天然气勘探前景。延长区气源岩及盖层条件良好,广泛发育了主要产气层山西组、下石盒子组的三角洲前缘、三角洲平原、滨浅湖等沉积;储集层以石英砂岩为主,次为岩屑砂岩,具低孔、低渗特点。根据储集层岩石特征、物性特征、孔隙结构特征,将延长区上古生界储集层划分为4类,工业气流一般都形成于Ⅰ至Ⅲ类储集层,Ⅳ类储集层基本不具备储气能力。不同类型储集层分布比较分散,是本区普遍含气却产量偏低的原因之一。研究区子长—延川—延长一带,多期河道叠加发育,砂体厚度大,已见到较好的含气显示和工业气流井,是极富希望的天然气勘探区。图3表2参15
The natural gas exploration in Yanchang area, southeast of the Ordos Basin, is of low degree. Based on the analysis of palaeogeographical pattern, sedimentary facies and distribution characteristics, reservoir rock characteristics and reservoir conditions in the area, prediction is made for the Upper Paleozoic Shanxi Formation Stone box sub-group natural gas prospecting. The gas source rocks and caprocks in the extension area are well-developed, and the delta front, delta plain, shallow lake and other sediments of the Shanxi Formation and Lower Shihezi Formation of the major gas-producing zones are widely developed. The reservoirs are mainly quartz sandstone, Debris sandstone, with low porosity and low permeability characteristics. According to reservoir rock characteristics, physical properties and pore structure characteristics, the Upper Paleozoic reservoirs in the extension area are divided into four types. Generally, industrial gas flows are formed from type I to type III reservoirs. Type IV reservoirs are basically not equipped Gas storage capacity. The distribution of different types of reservoirs is relatively scattered, which is one of the reasons for the low gas yield in this area. In the study area, the extension of Yanchuan-Yanchang area, multi-period river courses are superimposed and developed, and the thickness of the sand body is large. Good gas-bearing displays and industrial gas-flow wells have been found, which is a promising natural gas exploration area. Figure 3 Table 2 参 15