东濮凹陷沙三段盐岩成因及层序地层划分

Origin of salt rock and classification of stratigraphic sequence for the third section of
Shahejie Formation in Dongpu Depression

赵俊峰 纪友亮 苏 惠 李星星

同济大学海洋与地球科学学院，上海 200092 中原石油勘探局测井公司，河南 濮阳  457001 中原油田分公司勘探开发科学研究院，河南 濮阳 457001

School of Ocean and Earth Science, Tongji University, Shanghai 200092, China Well Logging Company, Zhongyuan Petroleum Exploration Bureau, SINOPEC, Puyang 457001, China Research Institute of Exploration and Development, Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China

东濮凹陷沙三段高水位期沉积深灰色、暗色泥岩与少量重力流砂体，低水位期沉积盐岩、膏岩、低位三角洲与扇三角洲，从而形成纵向上深湖泥岩与蒸发岩、低位砂岩的频繁互层沉积。根据岩心资料、盐岩沉积序列特点及沙三段沉积期古气候和古环境特点，认为盐岩为浅水蒸发成因。深水相泥岩与浅水成因的盐岩频繁互层，说明沙三段沉积期湖平面变化频繁。基于盐韵律特征划分准层序的方法，使得层序地层划分更为符合东濮凹陷含盐地层的实际情况。

In the highstand period of the third section of Shahejie Formation in Dongpu Depression, dark grey and dark mudstone and a few gravity flow sandbodies were deposited. And salt rock, gypsum rock, lowstand deltas and fan deltas were developed in the lowstand period. As a result, deep lacustrine facies mudstone is interbeded with evaporite and lowstand sandstone in vertical. According to the core data, characteristics of sedimentary sequence of salt rock, palaeoclimate and palaeoenvironment of depositional stage, this paper indicates that the origin of salt rock is because of shallow water evaporation. The dark mudstone
deposited in deep water was interbedded with the salt rock deposited in shallow water, which showed that the lacustrine level changed frequently during the sedimentation of the third section of Shahejie Formation. Based on the method of parasequences identification with the salt rhythm characteristics, the sequence division accords with the practice in salt formation in Dongpu Depression.