车排子周缘白垩系清水河组砂体油气输导特征

Hydrocarbon migration in sand layers of the Cretaceous Qingshuihe Formation in Chepaizi and its surrounding areas

综合测井、录井、物性分析、地层水和地球化学等资料,在现代油气运移理论的基础上,从宏观与微观、平面与剖面等方面,研究了准噶尔盆地车排子周缘白垩系清水河组砂体的油气输导特征.清水河组发育扇三角洲分流河道砂体,顺物源的北西-南东方向连通性好,垂直物源方向的砂体受河道间泥岩的阻隔,连通性较差,底部发育一套连续稳定的砂砾岩是油气的优势运移通道.清水河组砂体主要为方解石胶结,处于中成岩阶段,发育较多溶孔,孔隙度均值为17.6%,为高孔中喉特征,微观连通性好.清水河组砂体地层水水型相同,均为NaHCO_3型,证实砂体的连通性好.来自沙湾凹陷深部的二叠系油气经断裂和不整合面运移至白垩系后,沿清水河组砂体从凹陷向凸起、由东南向西北部运移.综合多种因素分析,建立了清水河组砂体的油气输导模式.

On the basis of the modern theory on oil and gas migration,the characteristics of hydrocarbon migration of Qingshuihe Formation in Chepaizi uplift and its surrounding areas were studied from the macroscopic and microscopic plane and profile,combined with the logging data,petro physical analysis data,formation water data and geochemical,etc.Distributary channel sand bodies of fan delta developed in Qingshuihe Formation,which have good continuity in the northwest to southeast direction along the sediments transportation.The channels are separated by the interchannel mud-stones,so that they are less continuous in the perpendicular direction to the provenance.A set of continuous and stable glutenites at the bottom of Qingshuihe Formation is an advantageous oil and gas migration path.Sand bodies are mainly of calcite cementation and are in the middle diagenetic stage,so they have developed many solution pores,and the average porosity is 17.6%.They possess the characteristics of high porosity-medium throat and good micro connectivity.Sand bodies in the Qingshuihe Formation have the same type of formation water,NaHCO_3 type,indicating their good continuity.The permian hydrocarbon in Shawan sag migrated upwards along faults and unconformities first,and then kept moving through the sand bodies of Qingshuihe Formation from the sag to the uplift,towards the north-west direction.Hydrocarbon migration pattern in the cretaceous sand bodies of Qingshuihe Formation was set up by a comprehensive analysis of various factors.