注水开发油田水淹层混合液电阻率求取新方法

注水开发油田水淹层混合液的电阻率是求取剩余油饱和度的重要参数，但现有计算水淹层混合液电阻率的独立并联导电模型和充分混合导电模型未得到试验验证。为此，通过模拟储层温度压力条件下的岩心水驱油试验，证实水淹过程中注入水与原生束缚水混合情况介于完全独立与充分均匀混合2种状态之间的基础上，对独立并联导电模型进行了改进，并利用试验数据拟合了混合液电阻率与当前含水饱和度的函数关系，与印度尼西亚公式结合，建立了水淹层混合液电阻率和含水饱和度的数学模型，给出了求解方法及步骤。利用建立的数学模型求取了W油田X井水淹层混合液的电阻率和含水饱和度，结果表明，利用改进的并联导电模型计算出的含水饱和度与密闭取心分析结果吻合良好，平均绝对误差为-0.3%，与独立并联导电模型和充分均匀混合导电模型的计算结果相比，计算精度得到较大地提高，而含水饱和度是根据混合液电阻率求取的，这也说明水淹层混合液电阻率的计算精度得到了提高。研究结果表明，利用改进的并联导电模型能够准确计算注水开发油田水淹层混合液的电阻率和含水饱和度，可进行推广应用。 

A New Method to Determine the Resistivity of Mixed Liquids in Water-flooded Layers of Oilfields by Water-flooding Development

The resistivity of mixed liquid in a water-flooded zone of an oil field developed by water injection is an important parameter for calculating residual oil saturation,but the existing independent parallel conductivity model and fully-mixed conductivity model for calculating the resistivity of mixed liquid in water-flooded layer have not been verified by experiments. Therefore,the independent parallel conductivity model has been improved by simulating core oil displacement tests on the basis of verifying the mixed state of injected water and primary bound water during water-flooding,which is in between the separate state and fully mixed state,and used the test data to fit the relationship between the resistivity of a mixed liquid and the current water saturation.Combined with the Indonesia Equation,a mathematical model for resistivity and water saturation of mixed liquid in water-flooded layers has been established to solve.By using the newly established mathematical model,the resistivity and water saturation of mixed liquid in water-flooded layer in the Well X of W Oilfield have been determined.The results showed that the water saturation determined by the modified parallel conduction model coincided well with the analytical results of close coring,with the average absolute error as -0.3%,the calculation accuracies of the new techniques were improved significantly compared to those determined by the independent parallel conductivity model and a fully-mixed conductivity model. Since the water saturation was determined in terms of the resistivity of a mixed liquid,it was concluded that the calculated accuracy of resistivity in water-flooded layer was also improved significantly.Relevant research results indicated that the modified parallel conductivity model could accurately determine the resistivity and water saturation of mixed liquid in water-flooded layers of oilfields which were developed by water flooding,and which could be developed more extensively in the future.