轴向重力流沉积:一种重要的深水储层——以东海盆地丽水凹陷明月峰组为例

东海盆地丽水凹陷中部丽水36-1含气构造的主要含气层段为明月峰组三级层序的低水位体系域砂体.对该区沉积背景、岩芯、沉积构造、粒度、测井、地震等资料的分析结果表明,该低水位体系域砂体为轴向重力流沉积,可划分出水道和漫溢2个亚相以及水道轴、水道砂坝、近漫溢、远漫溢4个微相,岩芯中可识别出7种岩相类型,丽水凹陷轴向重力流水道顺北东向展布的断槽呈带状展布.在沉积特征分析的基础上,分析了丽水凹陷轴向重力流水道的成因及其油气成藏特征,认为轴向重力流水道是该区一类重要的储集体,具有良好的成藏条件,丽水凹陷沿灵峰大断裂还应该有类似的储集体发育.

One Kind of Important Deep-Water Reservoir: The Longitudinal Gravity Currents Sediments——A Case Study in Mingyuefeng Formation in Lishui Sag, East China Sea Basin

Lishui 36-1 gas-bearing structure,an important discovery in East China Sea Basin in the recent years,is located in the middle part of Lishui Sag.The major gas-bearing interval of the structure is the sand body of low stand system in the Lower Mingyuefeng Formation.There have been controversial on the sedimentary facies type of the sand body.According to the study,the sand body should be the longitudinal gravity currents sediments which could be divided into two subfacies eg.gravity currents channel and overbank,and four microfacies eg.channel axis,channel bar,close overbank and distal overbank.Seven lithology facies are recognized in the rock core.The longitudinal gravity currents sediments bandly distribute along the half-garben like faulted trough.The paper discusses the genesis of the longitudinal gravity currents sediments and analyses its pool-formed characteristics.It is revealed that the gravity channel is an important reservoir with a good pool-formation combination and exploration potential in the area.