东营凹陷岩性圈闭油气充满度及其主控因素

TRAP FILL OF LITHOLOGIC POOLS AND ITS MAIN CONTROLLING FACTORS IN DONGYING SAG

岩性圈闭油气充满度的实际统计结果表明 ,东营凹陷岩性圈闭油气充满度分布在 6 8%～ 94 1% ,平均为4 6 5 % ,其中 4 6 7%的岩性圈闭油气充满度大于 5 0 % ,最大充满度为 94 1%。孤立砂体岩性圈闭油气充满度较高 ,平均达到 6 0 % ,而断层侧向沟通的岩性圈闭油气充满度较低 ,平均为 4 0 %左右 ;沙河街组三段中下亚段的岩性圈闭油气充满度高 ,为 5 2 % ,而沙河街组二段的岩性圈闭油气充满度低 ,仅为 2 3%。砂岩透镜体油气藏充满度主控因素的主因子分析结果表明 ,东营凹陷岩性圈闭油气充满度的第一控制因素是运移条件 ,具体体现在与洼陷生烃中心的距离、切割砂体的断层数量和剩余压力 ;第二控制因素为岩性圈闭的接受条件 ,即岩性圈闭的物性 (平均孔隙度和平均渗透率 )和岩性圈闭的几何特征 (岩性圈闭厚度和面积 ) ;

Dongying sag is the largest petroliferous region in Jiyang depression,Bohai Bay basin, which is the largest reserves distribution region in the lithologic pools, Jiyang depression. The main reservoir rock of lithologic pools in Dongying sag is sandstones in the middle and lower parts of the 3rd member of Shahejie Fm(Es 3).The main source rock is mudstones deposited in the Es 3 and the lower part of Es 4. The exploration results of lithologic pools in Dongying sag show that the lithologic traps has a great variation in trap fill in Dongying sag. In order to study the trap fill as well as its distribution and controlling factors in lithologic pools,the methods of statistic analysis and principal factor analysis have been used. In general,the trap fill in the lithologic pools of Dongying sag ranges from 6 8% to 94 1%,with an average value of 46 5%. Among these,50% lithologic traps has less than 40% trap fill; 46 7% lithologic pools is more than 50%, only a few trap fill is more than 80%, with the maximum value of 94 1%.In terms of the types of sandbody,the trap fill in lithologic pools of sandbody isolated by source rock is relatively high,with the average 60%,while the trap fill of the lithologic pools laterally connected with faults is relatively low, with average about 40%. In stratigraphic horizon,the lithologic pools in the lower and middle parts of Es 3 have trap fill as high as 52%, while the lithologic pools in the Es 2 is only 23% trap fill.In the lithologic traps of Dongying sag,the most important factor of controlling the trap fill is hydrocarbon migration conditions, including the distances between lithologic traps and source area, the quantity of faults and the residual pressure within the lithologic traps. The second one is the hydrocarbon charge conditions, i.e. the petrophysical property (average porosity and permeability) and geometry (thickness and area) of sandbody.The oil source condition has a relatively less influence on the trap fill, because of more abundant oil source in Dongying sag.