渤中凹陷沙二段生屑云岩的发现及勘探意义

Discovery of Bioclastic Dolostone in the Second Member of Shahejie Formation in Bozhong Depression and Its Significance in Oil Exploration

渤中凹陷中深层储层具有埋藏深、储集性能差以及预测难度大等特点,储集层质量是制约中深层油气勘探成效的关键。在QHD36-3油田沙二段中发现的生屑云岩和含陆源碎屑云岩等白云岩储层,其储集性能明显优于相同深度的碎屑岩储层,将成为中深层高产油气层勘探的新领域之一。研究表明,生屑云岩等白云岩储层的形成主要受古地貌、古水深等因素控制,同时距离物源区的远近影响其发育程度。建立相应的沉积模式,对以生屑云岩和含陆源碎屑云岩等白云岩为目的储层的油气勘探至关重要。

Due to the characteristics in deep buried depth, poor physical properties of reservoir and difficulty in the effective reservoir prediction, the exploration of mid-deep .oil and gas in mid-deep reservoirs is constrained mainly by reservoir quality. In QHD36-3 oil field, the storage properties are significantly superior to those of clastic reservoir at the same depth, including bioclastic dolostone and terrigenous clastic dolostone discovered in the second member of Shahejie Formation, and it will be one of the new fields in the mid-deep oil and gas exploration. This study suggests that the formation of dolomite reservoir is mainly affected by paleogeomorphology, paleao-water depth, and development degree, which is affected by the distance from the source area. The bioclastic dolostone formed by chemical and biochemical depositions is distributed in shallow to deep lake areas, and the reserving spaces include interlayer fractures and solution channels. Under the guidance of the sedimentary principle, the paper proposes a mixed sedimentation model of bioclastic dolostone in the second member of Shahejie Formation in Bozhong depression and further discusses the controlling factors of the mixed sedimentation. The establishment of the corresponding deposition pattern is essential for the oil and gas exploration related with bioclastic dolostone and terrigenous clastic dolostone.