东营凹陷北带沙四下亚段深层砂砾岩储层储集空间特征及成因机制

Reservoir-space Characteristics and Genetic Mechanism of Deep Glutenite Reservoir of Es4x in the North Zone of the Dongying Depression

东营凹陷民丰洼陷北带沙四下亚段深层砂砾岩储层储集空间特征及成因机制认识不清的问题,给该地区油气勘探带来了极大的风险。综合运用薄片鉴定、扫描电镜观察、流体包裹体分析及岩心物性分析等多种技术方法,结合压力演化史、油气成藏史、有机质热演化史等研究成果,对东营凹陷北带沙四下亚段砂砾岩储层储集空间特征及成因机制进行了系统研究。结果表明,东营凹陷北带沙四下亚段砂砾岩储层储集空间以残余原生孔隙为主,相对含量占60%以上,含有少量的次生溶蚀孔隙及微裂缝。在早期异常高压、早期油气充注以及膏岩层的发育等多种因素的综合作用下,东营凹陷北带沙四下亚段砂砾岩储层原生孔隙得以有效的保存至深层,从而为油气聚集提供了优质的储集空间;沙四下亚段深层砂砾岩储层经历了酸性→碱性→酸性的溶解过程,溶解作用相对较弱,次生孔隙含量低,对储层物性的贡献量小。

The reservoir-space characteristics and its genetic mechanism of deep glutenite reservoir in the lower part of the fourth member of the Shahejie Formation（Es4）in the north zone of the Minfeng Sag in the Dongying Depression haven＇t been clearly understood, and it has brought out great risks to hydrocarbon ex- ploration. Based on a combination of thin-section identification, scanning electron microscope（SEM）obser- vation,fluid inclusion analysis and an analysis of core properties,in addition to knowledge on the pressure evolution history, the history of hydrocarbon accumulation and the thermal evolution of organic matters, systematic study has been carried out about the reservoir-space characteristics and its genetic mechanism of glutenite reservoir in Es4 in the north zone of the Dongying Depression. The reservoir-space of glutenite reservoir is mainly residual primary pores in Es4 in the north zone of the Dongying Depression whose rela- tive content is more than 60% ,with a small amount of secondary dissolution-pores and microcrack. As a re- sult of the combination of early abnormal high pressure, early hydrocarbon-filling as well as the develop- ment of gypsum-salt bed,the primary pores of the glutenite reservoir in Es4x in the north zone of the Dongy- ing Depression are effectively reserved to the deep, which has provided high-quality reservoir-space for hy- drocarbon-accumulation. The glutenite reservoir has experienced the dissolution process of ＂acid-alkaline- acid＂,and the dissolution is weaker with a small amount of secondary pores,which contributes little to its physical properties.