渤海辽中凹陷古近系沉积演化与有利区带预测——以辽东湾地区A油田为例

Sedimentary Evolution of Paleogene and Prediction of Favorable Zones in Liaozhong Sag of Bohai Sea—A Case Study of A Oilfield in Liaodong Bay

摘要: A油田位于渤海辽东湾海域，东块沙河街组储层厚度较大，受沉积控制，储层呈现横向变化快的特点，西块东营组沉积厚度大，多期砂体叠置连片，隔夹层发育，而且井点多分布在构造高部位，分布不均匀，需要开展精细储层研究，进一步明确油田储层沉积特征。通过开展构造–沉积演化分析，同时充分利用岩石学特征、沉积构造、测井相特征等开展相分析和沉积环境研究，结合对录井资料、岩石结构、粒度分析以及电性特征分析等，在渤海A油田东营组和沙河街组识别出沉积相类型。综合分析油田区域范围内各地层的沉积环境，分析认为东二段主要为三角洲相沉积，东三段主要为辫状河三角洲和湖泊相沉积，沙河街组主要为扇三角洲和湖泊相沉积，从而进一步深化了沉积演化认识。研究结果表明，受构造沉积综合控制，5、6井区依附于走滑断层，位于沟谷与物源供给配置较好的区域，是导致砂体富积、东营组高砂地比层段的主要原因。

Abstract: A oilfield is located in Liaodong bay of Bohai Sea; the reservoir thickness of Shahejie formation in the east block is relatively large which is governed by the depositional; it shows the characteristics of rapid lateral change of the reservoir, Dongying formation in western block has a large sedimentary thickness, multistage sand body superimposed contiguous, interlayer is in a high degree of development and the good points are mostly distributed in the high parts of the structure, with uneven distribution. Therefore, it is necessary to carry out accurate reservoir research to further understand the reservoir sedimentary characteristics. Through structural sedimentary evolution analysis, facies analysis and sedimentary environment research are carried out by making full use of petrological characteristics, sedimentary structures and logging facies, and combined with logging data, rock texture, grain size analysis and electrical characteristics analysis, sedimentary facies types are identified in Dongying Formation and Shahejie Formation of Bohai A Oilfield. Through comprehensive analysis of the sedimentary environment of each layer in the oilfield area, it is considered that delta sedimentary facies are developed in the second stage of Dongying formation, braided delta facies and lacustrine facies are developed in the third stage of Dongying formation, fan delta facies and lacustrine facies are mainly developed in the Shahejie formation, and it deepens the understanding of sedimentary evolution. The research results show that, under the comprehensive control of structural sedimentation, well blocks 5 and 6 are attached to strike slip faults and located in the area with a good allocation of valleys and provenance, which is the main reason for sand body accumulation and high sand to ground ratio interval of Dongying formation.