柴西南区古近系岩性圈闭形成期次分析

从岩性圈闭的形成机理出发,应用综合泥岩排替压力、砂岩孔隙度和盆地演化史的定量方法分析了柴西南地区古近系的岩性圈闭的形成期次.首先通过岩心分析法、测井孔隙度-含油饱和度交汇图版法及采油强度分析法等方法确定的含油储层的临界孔隙度来分析储层的有效性,其次根据泥岩盖层封盖能力综合评价参数等级确定的盖层临界排替压力分析盖层的有效性,再次结合盆地埋藏演化史定量分析了岩性圈闭形成期次.结果表明,柴西南区岩性圈闭的形成具有早期性和多期性的特点.

Analysis of the formation stages of the Paleogene lithologic traps in the southwestern Caidamu Basin

This paper aims at analyzing the formation stages of the Paleogene lithologic traps in the southwestern party of Caidamu Basin.First,the critical porosity of the oil-bearing sandstone reservoirs is determined by three methods of core analysis,logging porosity——oil saturation crossplot and oil production intensity analysis,it is combined with the true reservoir porosity to analyze the validity of the reservoirs;then,the critical displacement pressure of the caprocks is determined by the comprehensive assessment of their closure to make sure whether these caprocks are valid or not;finally,by combining the results above with the bury and evolution procedure of the basin,the formation stages of the lithologic traps to are quantitatively determined.It is shown that,the lithologic traps are characterized by early formation and multi-stage deposition.The initial lithologic traps are formed in the final stage of Oligolene series,and they developed in the lower member of lower Gancaigou formation.The study result of this paper can provide the important guidance for the exploration of the lithologic traps in the southwestern party of Caidamu Basin.