川东北元坝地区膏盐岩盖层分布特征

Distribution of Gypsum-Salt Cap Rocks in Yuanba Area of Northeastern Sichuan Basin

勘探已证实,川东北元坝地区海相碳酸盐岩地层中蕴藏着丰富的油气资源。目前元坝气田油气成藏研究成果丰富,但盖层研究相当薄弱。利用测录井资料,分析该区膏盐岩典型的测井响应特征,精细解释膏盐岩,统计不同层位的膏盐岩厚度。结果表明,元坝地区膏盐岩在纵向上主要分布在雷口坡组、嘉陵江组以及飞仙关组四段,其中嘉四-嘉五段和嘉二段厚层膏盐岩单层厚度和累计厚度最大;在平面上,这两套膏盐岩分布广泛,总体有西薄东厚,北薄南厚的特点,连续性好,厚度大,是区域优质盖层。

It has been confirmed from exploration that Yuanba area in northeastern Sichuan basin is rich in oil-gas resources in its marine carbonate reservoir.But at present,fewer researches focus on its cap rock studies.This paper analyzes the typical well logging response of the gypsum-salt cap rock,and by fine interpretation of this rock,presents their statistical thicknesses in different horizons.The results show that the gypsum-salt zones are vertically distributed in Leikoupo formation,Jialingjiang formation and the fourth member of Feixianguan formation,of which Jia No.4-Jia No.5 and Jia No.2 members as two sets of gypsum-salt rocks are of the largest single thickness and cumulative thickness.In plane,these two sets of gypsum-salt rocks are characterized by thinning to the west and north and thickening to the east and the south,as well as good continuity and big thickness,which should be the high-quality cap rocks in this region.