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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 unclear understanding of the reservoir space characteristics and genetic mechanism of the deep glutenite reservoir in the sub-fourth member of Shahejie Formation in the northern Minfeng Depression of Dongying Depression poses a great risk to oil and gas exploration in this area. Based on the research results of thin-section identification, scanning electron microscopy, fluid inclusion analysis and core physical property analysis, combined with the research results of pressure evolution history, hydrocarbon accumulation history and thermal evolution history of organic matter, Systematic study on the reservoir space characteristics and genetic mechanism of sandstone and gravel reservoir. The results show that the reservoirs of sandstone reservoirs in the lower part of Shahejie Formation in the northern part of Dongying Depression are dominated by residual primary pores, with the relative content accounting for more than 60%, with a few secondary dissolution pores and microcracks. Under the combination of early abnormal pressure, early oil and gas accumulation, and the development of gypsum rock, the primary pores of the sand-conglomerate reservoir in the fourth member of Shahejie Formation in the northern belt of Dongying Sag can be effectively preserved to the deep level, And the high-quality reservoir space. The deep sandy conglomerate reservoir under the sub-fourth member of the Shahejie Formation underwent acidic → alkaline → acidic dissolution process with relatively weak dissolution, low secondary porosity and small contribution to reservoir physical properties.