变质岩裂缝性油藏水驱油特征三维物理模拟

Three-dimensional physical modeling of waterflooding in metamorphic fractured reservoirs

为认识变质岩裂缝性油藏水驱油特征及改善水驱开发效果的机理,以渤海湾盆地JZ251S油藏为原型,根据相似理论设计了满足几何相似、运动相似、动力相似和双重介质特征参数相似的大尺度物理模型并开展了水平井立体开发水驱油实验,研究了双重介质油藏水驱油机理、影响因素以及不同注水方式的提高采收率特征。实验结果表明:1受毛细管力影响的渗吸作用是双重介质油藏基质系统水驱油的主要机理;2无论基质是否出油,见水后的含水上升趋势均可划分为2个阶段,第1阶段为见水初期的快速上升段,第2阶段为中高含水期的缓慢增加段;3驱替速度是决定油藏无水采油期、含水率变化规律及最终采收率的主要因素;4与连续注水相比,间歇注水充分发挥了油水重力分异作用,对于降低阶段含水率与提高初期采油速度具有重要意义。

To understand water-oil displacement characteristics and the mechanism of improving waterflood efficiency in metamorphic fractured reservoirs, taking JZ251 S oil field as an example, a large-scale physical simulating model which meets the geometric similarity, kinematic similarity, dynamic similarity and dual media characteristic parameters similarity based on the theory of scaling criteria was designed to simulate the development of the reservoir by horizontal wells. The mechanism of water displacing oil in dual media reservoirs, the factors affecting fluid flow and waterflood characteristics, and the enhanced oil recovery（EOR） features of different water injection patterns were studied by experiments. The results show that：（1） Capillary imbibition is the main mechanism of enhancing matrix oil recovery in a dual media reservoir which is controlled by waterflooding;（2） whether or not there is crude oil draining from matrix, the water cut trend after water breakthrough can be divided into two stages, the first stage is quick rise stage of water cut in early water breakthrough period and the second stage is slow rise stage of water cut in mid-high water cut period;（3） displacement rate is the main factor controlling water-free production period, water cut trend and ultimate recovery;（4） compared with continuous injection, intermittent injection can give full play to the function of oil-water gravity segregation, reducing the water cut and improving the production rate of initial stages greatly.