低渗透油藏气驱“油墙”几何形态描述

摘要

在界定气驱类型的基础上，阐述了高压注气“油墙”形成过程。将气驱“油墙”形成机制概括为“差异化运移”和“加速凝析加积”；并首次区分出控制气驱见效高峰期生产效果的“先导性显式油墙”和“伴随性隐式油墙”两种类型。基于简化实际气驱过程的“三步近似法”、物质平衡原理和低渗透油藏气驱增产倍数等概念，给出了见气见效时单井组内“先导性显式油墙”的形态、宽度、高度、面积、周长、体积等几何产状要素的定义和描述方法。进一步提出“油墙集中采出体积”和“油墙集中采出时间”概念及其计算方法，为见效高峰期持续时间估算和气驱开发阶段定量划分提供了理论依据，也为注气开发方案编制提供了必要依据。%Based on the definition of the types of gas flooding, the forming of′oil bank′is described during the high pressure gas injection process.The gas drive"oil bank"formation mechanism is summed up as′differentiation in migration of crude oil components′and ′accelerated accretion of condensation near gas flooding frontier′.Two types of oil bank, ′leading explicit oil bank′and ′following implicit oil bank′are distinguished for the first time which control the dynamic performance of peak oil producing stage of gas flooding.On the basis of the concepts,′three-step method approximation of real gas flooding process′, material balance Principle and ′oil production rate multiplier due to gas flooding′, the geometric shape, width, height, area, circumference and volume of the′explic-it oil bank′within a well pattern are defined and the calculation method of these geometric occurrence elements are also provided.Further, two new concepts,′centralized recovery volume of oil bank′and′centralized recovery time of oil bank′are postulated, which will be useful for estimating the duration of peak oil production stage and for quantitative division of gas flooding lifetime, as well as the gas flooding planning.