苏北盆地高邮凹陷垛一段储盖组合定量分析及区带预测

Quantitative analysis of reservoir-cap rock assemblages of the first member of Sanduo Formation and prediction of favorable regions in Gaoyou Sag, North Jiangsu Basin

苏北盆地高邮凹陷三垛组一段成藏条件较好且砂岩整体发育,储盖组合条件是油气成藏的关键因素之一,开展有效储盖组合分析及区带预测是评价垛一段成藏条件和勘探有利区的重要工作。研究认为垛一段内部发育多套储盖组合,是控制各亚段油气成藏及富集程度的重要因素。首先,根据泥岩盖层的稳定程度将储盖组合分为区域和局部2类;其次,在定性分析的基础上,为了更准确地判别有效储盖组合,解剖油藏进行定量分析,利用含油亚段、上覆亚段砂地比与油气成藏的关系,明确有效储盖组合的判别界限,建立有效储盖组合的定量判别门槛界限值,总结了3种有效储盖组合类型(下储上盖型、自储自盖型和混合储盖型);在此基础上,开展了有效储盖组合的区带预测,优选出了有利区块,指出黄珏东部—邵伯西地区是勘探构造、隐蔽圈闭的有利地区,部署实施了构造、隐蔽圈闭的钻探均取得成功,实现了三垛组勘探隐蔽油藏的首次突破。

Overall, the reservoir forming conditions are good in the E2 s1（the first member of Sanduo Formation） of the Gaoyou Sag,North Jiangsu Basin. Sandstones were well developed. Reservoir-cap rock assemblage is one of the key factors controlling hydrocarbon accumulation. For the sake of evaluating reservoir-forming conditions and favorable exploration regions, it is important to analyze effective reservoir -cap rock assemblage and predict favorable regions. It was considered that there are multiple reservoir -cap rock assemblages, which are important factors controlling hydrocarbon accumulation and enrichment of each submember in the E2s1. Firstly, according to the degree of mudstone stability, the paper qualitatively divided the reservoir-cap rock assemblage into two sorts： regional and local. Secondly, in order to recognize effective reservoir-cap rock assemblage more accurately and based on the qualitative analysis, a quantitative oil reservoir analysis was completed. Through analyzing the relationship between sandstone ratio of the hydrocarbon and upper submembers with hydrocarbon accumulation, the boundary between reservoir rock and cap rock was confirmed, a quantitative evaluation threshold was built, and three types of effective reservoir-cap rock assemblage were identified （lower reservoir and upper cap rock assemblage, interior reservoir and cap rock assemblage, and mixed reservoir and cap rock assemblage）. Thirdly, based on the quantitative analysis, the favorable regions of effective reservoir -cap rock assemblage were predicted. Several regions have great exploration potential, such as the eastern Huangjue to western Shaobo area in the field of both structural and subtle traps, which have achieved good results in exploration.