退积型浅水三角洲前缘沉积特征及主控因素研究——以松辽盆地北部齐家–古龙凹陷葡萄花油层为例

A Study on the Sedimentary Characteristics and Main Control Factors of the Front of the Retreating Shallow-Water Delta—A Case from the Putaohua Oil Layer in the Qijia-Gulong Depression, Northern Songliao Basin

摘要: 齐家–古龙凹陷葡萄花油层发育典型退积型浅水三角洲前缘沉积砂体，具有较大的资源潜力，然而因为储层的厚度薄，发生变化快，使得后期岩性油气藏勘探开发难度增大。因此，本文对葡萄花油层沉积特征研究，明确退积型浅水三角洲沉积充填演化规律，研究地区主要发育浅水三角洲–湖泊相的沉积相类型，其中，以浅水三角洲前缘亚相为主，并且进一步可划分水下分流河道微相，席状砂微相，河口坝以及支流间湾微相。在葡萄花油层的沉积时期，物源的分布在浅水三角洲前缘亚相的外前缘区较远的区域，较少的沉积物被搬运到外前缘区，受到河流作用的影响比较小，以湖泊作用为主，席状砂分布规律与“浪控型”的发育相同，形成“水下分流河道末端席状砂”模式，研究成果为后续寻找隐藏性的岩性油气藏提供了重要的地质依据。

Abstract: The Putaohua oil layer in Qijia Gulong Depression has developed typical retreating shallow-water delta front sedimentary sand bodies, which have great resource potential. However, due to the thin thickness of the reservoir and rapid changes, the exploration and development of lithological oil and gas reservoirs in the later stage is more difficult. Therefore, this article studies the sedimentary of the Putaohua oil layer and clarifies the sedimentary filling and evolution rules of the retreating shallow-water delta. The study area mainly develops sedimentary facies types of shallow-water delta lake facies, among which the shallow-water delta front subfacies are the main ones, and can be further divided into three parts, namely typical underwater distributary channel, sheet sand, mouth bar, and tributary bay microfacies. During the sedimentation period of the Putaohua oil layer, the distribution of sediment sources was in a relatively distant area of the outer front area of the shallow-water delta front subfacies. Less sediment was transported to the outer front area and was less affected by river action, mainly lake action. The distribution pattern of sheet sand was the same as that of the “wave controlled” type, forming an “underwater distributary channel end sheet sand” pattern, The research results provide an important geological basis for the subsequent search for hidden lithological oil and gas reservoirs.