辽西低凸起中北段潜山油气藏泥岩盖层封闭能力评价

Abstract

为综合评价辽西低凸起泥岩盖层封闭能力，统计分析了辽西低凸起中北段潜山基础井资料，表明辽西低凸起潜山盖层主要由东营组和沙河街组泥岩盖层组成，其中以东营组泥岩盖层为区域性盖层，沙一段沙二段和沙三段泥岩盖层在JZ20-2、JZ25-1S潜山有分布，为局部盖层。选取泥质含量、突破压力、超压压力系数等参数研究微观特征，研究表明辽西低凸起潜山盖层主要存在泥岩毛细管压力封盖和超压封盖两种类型的微观机理，其中超压封盖主要分布在低凸起中北部JZ25-1S地区与JZ20-2地区。综合评价辽西低凸起中北段泥岩盖层封闭能力。结果表明：辽西低凸起中北段盖层以中等、好为主，好盖层分布较广。通过分析盖层与已发现油气藏关系，辽西低凸起中北段已发现油气分布在中等及以上盖层区域内，表明中等封盖能力的潜山盖层就能很好的封闭潜山油气。 In order to comprehensively evaluate low bulge mudstone caprock sealing ability, the data of buried hill basic well in Liaoxi low uplift are statistically analyzed. It shows that Liaoxi low uplift buried hills cover layer is mainly composed of dongying group and the shahejie formation. Among them, mudstone caprock of Dongying formation is a regional cap rock. And Sha 1, Sha 2 and Sha 3 mudstone cover are distributed in the JZ20-2, JZ25-1s buried hill, which are partial cap rocks. The parameters of shale content, breakthrough pressure and overpressure pressure coefficient were selected to study the microscopic features. The results showed that there were mainly two types of micro-mechanisms: Mudstone capillary pressure cap and overpressure sealing system. Overpressure sealing system is mainly distributed in low rising in north-central JZ25-1s region and the JZ20-2. A comprehensive evaluation of the sealing ability of mudstone cover in the northern section of Liaoxi low uplift was made. The results showed that the top layer of the northern section of the low bulge in the Liaoxi low uplift was medium and good, and the distribution of the good cover was wide. By analyzing the relationship between cap rock and reservoir that had been found, and the oil and gas that had been found in the medium and above cover area, which showed that the buried caprocks with medium cap ability can well seal the buried hill oil and gas.