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鄂尔多斯盆地是一个构造简单的大型多旋回克拉通盆地 ,面积约 2 5× 10 4 km2 。上古生界石炭—二叠系下部沉积的暗色泥岩、煤层和石灰岩有机质含量高、热演化程度高、生气能力强 ,为古生界气藏的形成提供了充足的气源 ;其中下部为一套河流、三角洲砂岩沉积 ,是上古生界的主要储层 ;而其上部的河漫湖相泥质岩为良好盖层。盆地周边在燕山期构造活跃 ,砂体发育 ,以构造圈闭为主 ;盆地内部构造稳定 ,在倾角不到 1°的西倾单斜上 ,南北展布的河流三角洲复合砂体与侧向河流间湾泥质岩 ,形成了近南北向的大型岩性圈闭。因此 ,盆地周边发育以构造控制为主的小型气藏 ,盆地内部则以大型岩性气藏为主 ,盆地西缘断褶带胜利井气藏和伊陕斜坡上的陕 141井区下二叠统山西组山 2段气藏等的存在就反映了这一特征。
Ordos Basin is a large-scale multi-cycle cratonic basin with an area of about 25 × 10 4 km 2. The dark mudstones deposited in the Lower Paleozoic Carboniferous-Permian are characterized by high organic matter content, high degree of thermal evolution and strong gas generation in the coal and limestone formations and sufficient gas source for the formation of Paleozoic gas reservoirs. Rivers and deltaic sandstone deposits are the main reservoirs of the Upper Paleozoic, while the Upper Pleistocene lacustrine mudstone is a good capping layer. The basin periphery is active in the Yanshanian period, and the sand body is developed mainly with structural traps. The interior of the basin is structurally stable. On the west slope of monocline inclined less than 1 °, the deltaic sand bodies and the lateral rivers Bay Bay mudstone, forming a large north-south lithologic traps. Therefore, the small-scale gas reservoirs dominated by structural control are developed in the periphery of the basin. Large-scale lithologic gas reservoirs are mainly located inside the basin. The Shengli well in the western margin of the basin and the lower two layers of the Shaan-141 well on the Yi-shan slope The existence of gas reservoirs, such as the 2nd member of Shanxi Formation, reflects this feature.