扇三角洲高分辨率层序地层对比及砂体分布规律

笔者依据岩心、测井资料,通过岩性、电性对比,对胡状集油田沙三中亚段4～8油层组的扇三角洲相储层进行高分辨率层序地层研究,确立了不同级次旋回界面和旋回类型的识别特征,将研究层段分为1个长期旋回和6个中期旋回。依据中期旋回对砂体沉积的控制作用以及垂直、平行物源方向短期旋回与古地貌的变化关系,确定了短期旋回的对比原则和对比方法,建立了短期旋回对比格架。短期旋回地层在中期基准面旋回的不同时期的砂体分布特征差异明显,是造成储层层间和平面非均质性的主要原因,在细分油气开发层系时应区别对待。

High-resolution sequence stratigraphic correlation of fan deltas and distribution characteristics of sandbodies

According to the core and well log data and lithologic and electric correlation, high-resolution sequence stratigraphic study has been conducted on the fan deltaic reservoirs in pay sets 4 to 8 of the Third Member of the Shahejie Formation in the Huzhuangji oilfield. The criteria for recognition of different orders of cycle boundaries and cycle types are established, and the studied section is divided into one long-term cycle and six medium-term cycles. The correlation principle and method of short-term stratigraphic cycles are determined and the framework of correlation of short-term cycles is established according to the controls of medium-term cycles on the deposition of sandbodies and relationship between the geomorphological change and types of short-term cycles parallel or perpendicular to the direction of the provenance. The distribution characteristics of sandbodies and reservoir properties in short-term cyclic sequences are notably different in different phases of a medium-term base-level cycle, which is the main cause responsible for serious reservoir interlayers or plane heterogeneities. It should be taken into account when the sequences of strata which are to be exploited are distinguished in detail.