东营凹陷现今大规模超压系统整体分布特征及主控因素  

Distribution and Major Control Factors of the Present-Day Large-Scale Overpressured System in Dongying Depression

作　　者：何生[1] 宋国奇[2] 王永诗[2] 郝雪峰[2] 王冰洁[1] 黎娜[1] 罗胜元[1] 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074 [2]中国石化胜利油田分公司,山东东营257015

出　　处：《地球科学（中国地质大学学报）》2012年第5期1029-1042,共14页Earth Science-Journal of China University of Geosciences

基　　金：国家“十二五”科技重大专项基金(No.2011ZX05006);国家自然科学基金项目(No.41072093);构造与油气资源教育部重点实验室基金(No.TPR-2010-10)

摘　　要：东营凹陷为超压富烃凹陷,钻井揭示该凹陷现今大规模超压系统出现在始新统沙三-四段烃源岩层系.根据大量的钻杆测试(DST)数据,实测沙三-四段砂岩异常高压的深度范围约在2200～4400m,剩余压力约为4～40MPa,压力系数为1.2～1.99.根据钻井和测井以及地震速度资料解释,超压带钻井泥浆密度明显增加,超压泥岩层具有偏离正常趋势的异常高声波时差测井响应和异常低地震层速度响应特征.综合解释超压系统顶界面埋深在2200～2900m,对应地温在90～120℃;超压顶界面深度随着烃源岩层系顶界埋深的增加而增加.超压系统范围内烃源岩层系样品镜质体反射率(Ro)分布在0.5%～1.2%,沙三中、下亚段-沙四上亚段成熟烃源岩(Ro为0.5%～1.2%)及其生油作用控制了超压分布的主体区域,佐证了东营凹陷现今大规模超压发育区与烃源岩生油增压有成因联系;成熟烃源岩的累积厚度、埋深及热成熟度是超压系统整体分布特征和超压发育幅度的主控因素;断裂系统和输导性砂体对东营凹陷沙三-四段烃源岩层系中发育的大规模超压系统的分布特征和结构变化具有重要影响.Dongying depression is a typical overpressured depression with abundant petroleum resources,and the present-day large-scale overpressured system occurs in the Eocene third and fourth members of the Shahejie Formation(Es3-Es4) in the depression as evidenced by drill stem test(DST) data,and the source rocks also exist within the overpressured system.Based on a large number of drill stem test(DST) data,the burial depths of overpressured sandstone reservoirs range from 2 200 to 4 400 m with excess pressures of about 4 to 40 MPa and pressure coefficients of 1.2 to 1.99.According to the integrated interpretation of drilling,well logging and seismic velocity data,the large-scale overpressured system is associated with significant increase in drilling mud density,as well as abnormal high sonic transit times with deviation from the normal trend and low seismic interval velocity responding.On the whole,the burial depths of the top overpressured surface range from 2 200 to 2 900 m with corresponding formation temperatures ranging from 90 to 120 ℃,and the depths of top overpressure surface increase as the burial depths of source rocks deepen.Many evidences suggest that the oil generation from the source rocks is the major cause of the present-day large-scale overpressured system in the Es3-Es4 of Dongying depression.This study indicates that the large-scale overpressured system is well developed where the cumulative thickness of mature source rocks is thick and source rocks remain in oil-generating stage of thermal evolution with vitrinite reflectance values varying from 0.5% to 1.2% of overpressured source rocks,and the fault system and sandstone transporting layers have great influence on the distribution and construction change of the large-scale overpressured system in the Es3-Es4 of Dongying depression.

关 键 词：超压系统 生油增压 成熟烃源岩 沙三-沙四段地层 东营凹陷 

分 类 号：P618.13[天文地球—矿床学]