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剩余油的开采是提高采收率的关键。以套管作为线源,通过给套管供电来观测地层的电位,以此来研究油田注水和剩余油分布情况。由于地质结构因素,许多套管井都是水平井。在地层正演过程中,水平井与直井的地层分布有很大区别,所以研究倾斜线源三维地电场是有必要的。以麦克斯韦方程为基础,利用COMSOL软件建立了基于线源的套管井地层正演模型,分析了三种不同地质结构下的地层响应模型的网格剖分方法、电场分布与电势分布情况。仿真结果表明,以套管作为线源,相同模型使用倾斜线源和垂直线源时地层电阻率分布是有区别的。如井倾斜的方向基本一致,且偏移的距离远远小于井的深度,可以把倾斜井当作直井来处理,否则实际中把斜井当作直井来处理会引起较大的误差。
Remaining oil recovery is the key to improving oil recovery. Using casing as a source, the electric potential of the formation was observed by supplying power to the casing to study the waterflooding and residual oil distribution in the oilfield. Due to the geological structure, many cased wells are horizontal wells. During the process of stratum forward formation, the stratigraphic distribution of horizontal well and vertical well is very different, so it is necessary to study the 3D geoelectric field of inclined line source. Based on Maxwell’s equations, a stratified forward modeling method of cased-hole well was established by using COMSOL software. The meshing method, electric field distribution and potential distribution of stratigraphic response model under three different geological structures were analyzed. The simulation results show that the casing resistivity distribution is different when using the casing as the line source and the same model using the inclined line source and the vertical line source. If the direction of well inclination is basically the same, and the offset distance is far less than the depth of the well, the inclined well can be treated as a vertical well. Otherwise, it is actually caused that the inclined well is treated as a vertical well and causes a large error.