伊宁凹陷中二叠统膏盐岩的发现、特征及油气地质意义

The discovery of Middle Permian gypsolith gypsolyte in Ili Basin of Xinjiang and its petroleum geology significance

膏盐岩常常是油气藏的盖层,研究伊宁凹陷是否存在膏盐岩及膏盐岩与烃源岩的关系对油气勘探具有重要意义。通过野外地质剖面精细测量、实验室X射线衍射分析、岩石薄片原岩恢复,在中二叠统中部发现含膏地层。其中潘津布拉克剖面含膏地层厚53m,膏盐岩层厚20m,最大单层厚度13m,其他剖面均有分布。区内含膏地层厚度为36~53m,分布稳定。中二叠统优质烃源岩主要发育在膏盐岩层之下,厚度大,分布广,有机质类型好,成熟度适中,生烃潜力大。盐下油气成藏条件优越,野外剖面油苗丰富,是油气勘探的主攻方向。

Middle Permian gypseous-salt rock occurred in the Yining sag of Xingjiang is studied through cross section measurement, X-ray diffraction analysis and observation of thin sections so as to discuss its relation with oil and gas. It shows that the Panjinbulake section contains 53 m of gypseoussalt rock formation, with 20 m gypsum layers and with largest single layer of 13 m. Gypseous-salt rock is also found and distributed in other cross sections. Generally, the distribution of gypseous-salt rock formation is stable in the area with a thickness of 36 ？53 m. High-quality hydrocarbon source rocks of Mid-Permian mainly develop under the gypseous-salt rock formation. The hydrocarbon source rocks of Mid-Permian are characterized by large thickness, stable distribution, quality organic type, medium maturity, great hydrocarbon generation potential, superior hydrocarbon accumulation condition and rich seepage in the field. Therefore, it is the main target of oil and gas exploration.