关于南海北部深水重力流沉积问题的讨论

深水沉积主要泛指陆架以外的沉积,尤以沉积物重力流成因的沉积受到深水油气勘探界的关注,它的沉积成因、过程和相组成均与河流、三角洲、浅海等牵引流沉积有很大的差异。当前南海北部大规模深水勘探已经全面展开,正确认识深水重力流沉积具有重要意义,但由于我国油气勘探对深水重力流沉积缺乏勘探实践,目前对深水重力流沉积有不同的理解,如深水重力流沉积一定要在多深的水下沉积,深水重力流沉积的判识一定要有深水环境的标志,深水重力流沉积作用保留在地层中的沉积层理构造特征一定是重力流流态的等。通过南海北部深水实钻资料和沉积体系的研究,认为深水重力流沉积具有偶发而动、沿坡搬运、择低而积、有限分布的特点。陆架坡折带以外的粗陆源碎屑沉积以重力流沉积成因为主,低位体系域的重力流更易于发育砂岩储层。陆坡区深水重力流沉积的特点表明储层识别是深水勘探的关键工作。

Some reviews on deep-water gravity-flow deposition in the northern South China Sea

deep-water gravity-flow depositions are generally inferred that the sediments deposited by gravity flows outsidea continental shelf, the genesis, process and facies of such deposits show significant differences from traction current sediments such as fluvial, deltaic and shallow marine deposits.Currently, adeep-water exploration of large scale has been launched in the northern South China Sea.How to correctly understand the deep-water gravity-flow deposition shows its significance.However,the petroleum exploration lacks the practical experience in the deep-water gravity-flow deposition exploration in our country, and the understandings regarding to the deep-water gravity-flow deposition are different.For example, deepwater gravity-flow deposition have to be deposited at certain water depth; identification of deep-water deposits must request deep-water environment marking; the strata sedimentary bedding structures caused by deep-water sedimentary process must have gravity flow pattern and so on.According to the drilling data and the study of sedimentary systems of the northern South China Sea, the features of the deep-water gravity-flow deposition win be described as event-trigger mechanism, transportation along the slope, deposition in low places, and limited distribution.The coarse continental clastic matter deposits outside the continental shelf break show the genesis of gravity flow sediments and sandstone reservoir developed easily in low stand system tract of gravity flow.the key of the deep-water exploration is the reservoir identification, which characterized by continental slope deep-water deposits.