Characteristics Of Conglomerate Reservoirs In The Lower Part Of The 3rd Member Of Shahejie Formation In The Middle And Southern Segments Of Shulu Sag

Shulu Sag lies in the southern part of Jizhong Depression in Bohai Bay Basin.It is a Single-break graben basin which eastern part is a fault and western part overlap on the near bulge.It is the NE trending, and develop based on the Mesozoic tectonic. The success of Shutan 1 and Shutan 2 well area indicates that the studying area has some exploration potential. Combining the data of cores,petrographic thin sections, reservoir physical properties and X-ray diffraction analysis, in this paper we carefully studied the petrologic characteristics of reservoir, diagenesis types and reservoir space types. Our research also analyses main influencing factors of reservoir development,and finally builds a set of reservoir evaluation method which helps us conduct reservoir classification evaluation and forecasting.Shulu Sag Shahejie Formation conglomerate is mainly composed of carbonate gravels which include limestone and dolomite. According to particle sources and methods of support,the conglomerate can be subdivided into five types including the grain-support terrigenous source conglomerate, the grain-support mix sources conglomerate, the grain-support lacustrine source conglomerate, the matrix-support terrigenous source conglomerate and the matrix-support mix sources conglomerate.The grain-support terrigenous source conglomerate and the matrix-support terrigenous source conglomerate have the largest number in this area.Our research finds that Shulu Sag Shahejie Formation conglomerate has experienced compaction, pressolution, cementation and dissolution.The purpose layer of the studying area lies in the late diagenesis A stage and late diagenesis B stage.The former mainly develop the secondary pores,and the later mainly develop fissures.The reservoir space types in our study area include pores and fissures.Pores can be divided into dissolution pores(holes) and intercrystalline pores. Fissures can be divided into tectonic fractures, pressolution fissures, gravel edge fissures, shrinkage fissures and fissures in conglomerate. dissolution pores(holes), intercrystalline pores and tectonic fractures are the most important reservoir spaces.After carefully studied main influencing factors of reservoir development, we build a set of reservoir evaluation standard which takes conglomerate type, tectonic activity and gravel component as evaluating indicators.Based on this standard,we evaluate reservoirs in different areas and depths.