论文部分内容阅读
本文在回顾当前国际上深水沉积研究热点的基础上,结合在墨西哥湾深水研究的成果系统描述了深水沉积的定义、形成机理、深水沉积层序及深水沉积构成要素的特点.深水沉积主要是在重力流作用下深水环境的沉积,主要形成于相对水平面下降和早期上升的时期,主要分布在低位体系域中.深水层序以凝缩段为边界,块状搬运沉积最早形成并直接位于层序界面上,其上被河道-天然堤沉积所覆盖.典型深水沉积的要素主要由河道、天然堤及越岸沉积、板状砂、块状搬运沉积等构成,这些沉积要素时空上有序地分布.深水河道是物源的主要通道和沉积的重要场所,从上游至下游河道弯曲度增加,能量逐渐减弱.侧向迁移明显,垂向上由富砂的顺直河道演化为相对富泥的弯曲河道.天然堤及越岸沉积以泥质为主,天然堤沿河道呈楔状分布,其近端砂岩含量高,地层厚且倾角较陡;远端砂岩含量低,地层薄且平缓,侧向连续性好但垂向连续性差.板状砂主要为深水扇前缘非限制性沉积,可分为块型和层型.块型侧向连续性好,同时垂向连通性高.层型侧向连续性好,垂向连通性差.块状搬运沉积主要是低水位期坡上沉积物失稳形成的各类滑塌体及碎屑流,其对下伏地层侵蚀明显,分布广泛,变形构造常见,可作为油气良好的封盖层.
Based on the review of current international research on deepwater sediment, this paper describes the definition of deep-water sediment, formation mechanism, deep-water sedimentary sequence and components of deep-water sediment based on the results of deepwater research in the Gulf of Mexico. The deposition of deep-water environment under the action of gravity flow is mainly formed during the period of relative horizontal decline and early rise, and is mainly distributed in the lower system tract. The deep-water sequence is characterized by the condensing section as the boundary, Which is covered by channel-natural dike deposits.The elements of a typical deep-water sediment mainly consist of river courses, natural dike and over-shore sediments, plate-like sand, massive transport sediments, etc. These sedimentary elements are spatially and temporally distributed . Deep water channel is the main source of sediment and sedimentary important sites, the curvature of the upper and lower reaches of the river increases, the energy is gradually weakened. Lateral migration is obvious, vertical from the sand-filled straight channel to rich muddy curved channel The natural dykes and offshore deposits are mainly muddy, while the natural dikes are wedge-shaped along the river courses with high sandstone content at the proximal end and thick stratum and steep dip angle ; The sand content in the distal end is low, the formation is thin and gentle, the lateral continuity is good, but the vertical continuity is poor. The plate sand is mainly non-restricted sedimentation in the front of deep-water fan and can be divided into block type and stratum type. Good continuity, high vertical connectivity, good lateral continuity, and poor vertical connectivity.The massive transport sedimentation is mainly composed of various types of slump and debris flow formed by the instability of sediments on the low water level , Which has obvious and widespread erosion to the underlying strata, common deformation structures, and can be used as a good capping layer for oil and gas.