萨尔图油田表外储层特征研究

Study on the Characteristics of Off-Surface Reservoirs in Saertu Oilfield

摘要: 萨尔图油田表外储层是大庆长垣重要的潜力储量类型，表外储层以泥质粉砂岩为主，油层薄、颗粒细，平均孔隙度24.1%，空气渗透率平均43.79 × 10⁻³ μm²，属中孔、特低渗~低渗透储层，含油饱和度30%~50%。平面分为决口泛滥型、局部变差型等5类，不同类型非均质性强、动用差异显著。渐变型连通性好，水驱动用程度40%~60%，化学驱后提升至60%~70%；独立型夹层阻隔、连通差，水驱动用不足10%。与表内砂体连通性、物性、沉积相带及开发方式是控制动用程度的核心因素，化学驱可显著改善动用效果。研究成果可为萨尔图油田表外储层水驱与化学驱高效开发提供地质依据。

Abstract: Off-surface reservoirs in the Sartu Oilfield represent an important potential reserve type in the Daqing Placanticline. Dominated by argillaceous siltstone, these reservoirs are characterized by thin oil layers and fine grains, with an average porosity of 24.1% and an average air permeability of 43.79 × 10⁻³ μm², classifying them as medium-porosity, extra-low to low-permeability reservoirs. Their oil saturation ranges from 30% to 50%. Laterally, they are divided into five types, including crevasse-flooding type and local deterioration type, which feature strong heterogeneity and significant differences in development performance across types. The gradational type exhibits good connectivity, with a waterflooding recovery degree of 40%~60%, which is enhanced to 60%~70% after chemical flooding. In contrast, the isolated type is characterized by interlayer barrier and poor connectivity, resulting in a waterflooding recovery degree of less than 10%. Connectivity with in-balance-sheet sand bodies, physical properties, sedimentary facies belts, and development modes serve as core factors controlling recovery degree, and chemical flooding can considerably improve development efficiency. The research results provide a geological basis for the efficient waterflooding and chemical flooding development of off-surface reservoirs in the Saertu Oilfield.