不同化学驱油体系微观驱油机理评价方法

为了分析胜利油田应用的3种化学驱油体系的微观驱油机理,并对其非均质油藏的适用性进行评价,利用微观刻蚀模型润湿性7级控制方法和波驱贡献比分析方法,结合现场情况,借助微观模拟驱油试验,开展了不同润湿性条件、非均质性条件和不同驱替阶段的化学驱油机理研究,建立了利用波驱贡献比评价化学驱油体系微观驱油机理的方法。试验表明:聚合物和二元复合体系在非均质级差1:9模型试验中水驱后采收率提高不足10%,平均波驱贡献比小于1.5,扩大波及的能力弱,主要驱油机理无法发挥;在各组非均质渗透率级差模型试验中,新型非均相复合体系的平均波驱贡献比大于3,说明其在非均质条件下扩大波及的能力强,主要是凝胶颗粒间歇式封堵和转向式扩大波及共同作用的结果。微观运移特征和驱替方式研究及现场试验表明,聚合物驱后的非均质油藏实施非均相复合驱,可以大幅度提高驱油效率和波及系数。 

Microscopic Flooding Mechanism of Different Chemical Displacement Systems

The microscopic oil displacement mechanism of three chemical flooding systems applied in Shengli Oilfield was studied,and its applicability in heterogeneous reservoirs was appraised.Using wettability controlling method for micro-etching model and contribution ratio analysis method of conformance efficiency to displacement efficiency,chemical flooding mechanism under different conditions and different displacement stages were studied through microscopic flooding experiment.In addition,a new method using contribution ratio analysis method of conformance efficiency to displacement efficiency to evaluate the microscopic displacement mechanism of chemical flooding system was established.Experiment results showed that oil recovery increase from polymer or polymer-surfactant flooding after water driving was less than 10% and contribution ratio of conformance efficiency to displacement efficiency was less than 1.5 in the model with permeability contrast of 1∶9,which verifies that polymer and polymer-surfactant system had a weak ability to expand conformance efficiency and the main drive mechanism could not be brought into full play.Experiment results also showed that average contribution ratio of conformance efficiency to displacement efficiency was greater than 3 from heterogeneous composite system in the models with different permeability contrasts,which verified that heterogeneous composite system had a strong ability to expand conformance efficiency and the main mechanism of oil displacement was the combination of intermittent sealing and enlarging conformance efficiency by changing direction of gel particles.The results of micro-migration and displacement mode research and field test showed that heterogeneous compound flooding can greatly enhance oil displacement efficiency and sweep efficiency for heterogeneous reservoirs after polymer flooding.