鄂尔多斯盆地北部盒8段古含气范围的地球化学特征

鄂尔多斯盆地盒8段气藏为深盆气藏。通过分析鄂尔多斯盆地苏里格庙地区盒8段储集层中有机包裹体的丰度、储集层的热解特征，并结合该区的构造演化和生烃演化等特征，探讨了苏里格庙北部盒8段气层的古含气边界的变化情况及天然气的保存条件。认为盒8段气层的分布范围在早白垩世末期达到最大，后期的构造抬升对气水边界的影响并不大，这是因为构造抬升后，气源岩的压力下降，增加了煤系地层中吸附气的脱附能力，为气藏补充足够的气体，从而使得古气水边界的分布与现今的差别不大。地层倾角的大小能影响天然气的富集和保存，地层倾角相对平缓的斜坡部位利于天然气的聚集，是高产气区。

THE GEOLOGICAL-GEOCHEMICAL ANALYSIS OF THE ANCIENT BOUNDARY OF THE GAS RESERVOIR OF HE 8 STRATUM IN THE ORDOS BASIN

The gas reservoir of He 8 stratum in the Ordos Basin is a deep basin gas reservoir. From analyzing the contents and the pyrolysis parameters of the hydrocarbons in the reservoir beds, combing the tectonic evolution and the hydrocarbon generation evolution, the authors discuss the variety of the boundary of the gas reservoir and preservation conditions of nature gas, and conclude that the boundary, little affected by tectonic rising, grew most at the late of Early Cretaceous. When the pressure of the stratum declined, the absorbed gas could be free. Therefore, the distribution of the ancient gas-water boundary is approximately accordant to today's. The preservative condition of the stratum is affected by tectonic obliquity. The slope with a low obliquity can keep natural gas easily and become the high yield region.