屏蔽电极可行性的理论分析与实验研究

Theoretical Analysis and Experimental Research for the Feasibility of Shield Electrode

在使用传统四电极电导传感器对油井产出液的含水率进行实际测量时,由于传感器两端电位近似为零而造成激励电流漏失,导致含水率测量精度下降。提出在原有四电极基础上增加两个屏蔽电极的改进方案,建立了含屏蔽电极电导传感器内电流密度分布的理论模型,并对屏蔽电极的宽度和间距进行了优化设计,理论上漏失程度可由原来的31.5%下降到0.36%。环状流型下的实验结果表明,屏蔽电极可有效减少漏失条件下激励电流的漏失,传感器测量精度有较大提高。大庆油田现场试验结果表明,传感器测量相对误差小于5%。

In order to decrease the exciting current leakage and improve the measuring precision ot water Iraction under oil-well logging application when using basic four-electrode conductance sensor, a new six-electrode conductance sensor characterized by adding two shield electrodes was proposed. A theoretical model of the current density distribution inside the new conductance sensor was instructed. The distance and width of the two shield electrodes were optimized ,and the leakage degree was reduced from 31.5% to 0.36% theoretically. The experiment was performed with reference to annular phase distributions in laboratory, and the results demonstrate that the two shield electrodes is feasibility and the measuring precision of water fraction is improved greatly. The trial result in Daqing oilfield shows that the measuring relative error of the new six-electrode probe is less than 5%.