考虑注水体积倍数及离子交换的水淹层剩余油评价方法

Evaluation method of remaining oil in water-flooded formation considering injected water volumes and ion exchange

准确求取注水开发过程中水淹层混合溶液矿化度和电阻率是评价油藏开发中后期储层水淹状况及剩余油饱和度的关键基础。通过了解岩心尺度不同矿化度水驱油岩电实验模拟矿场注水开发过程,理论分析建立考虑不同矿化度模拟地层水驱替过程注入水体积倍数及离子交换作用效率影响的混合地层水矿化度表征模型,准确表征了注水开发过程中储层混合流体性质变化,有效提升不同矿化度水驱过程中水淹层地层水电阻率计算精度。利用建立的方法在青海油田H区块实例井进行应用,计算水淹层含油饱和度与密闭取心分析含油饱和度符合率达到92.33%,解释水淹层与实际生产动态匹配性较好,证实建立模型的有效性,为水淹层高精度评价定量提供支撑。

Accurately calculating the salinity and resistivity of mixed solution in water-flooded layers is the key basis for evaluating the water-flooded condition and remaining oil saturation in middle-late development stage.This paper focuses on simulating water-flooding processes with varying salinities and measuring resistivity at the rock core scale.A novel model for calculating the resistivity of mixed solutions was developed,taking into account the efficiency of injected-water sweep and ion exchange.This model was formulated based on theoretical analysis and provides an accurate representation of the properties of reservoir mixed solutions during water-flooding.It significantly enhances the accuracy of mixed-water resistivity calculations.The established model was successfully used in H Block of Qinghai Oilfield and the calculated water saturation was consistent well with the core analysis result with the total coincidence rate reached 92.33%.The interpreted water-flooded layers were matched well with the actual production performance,the effectiveness of the established model was validated and lays a foundation for quantitative evaluation in the water-flooded layers.