利用垂直线源电成像技术获得剩余油分布

垂直线源电成像技术将套管井作为供电电流源,大大地增加了探测深度和成像精度,且可在不影响油井正常生产的情况下实施作业。所获得的视电阻率经反演成像后可得到深部目标储层中的真电阻率,然后利用电阻率与含油(水)饱和度的关系,获得目标储层中剩余油分布状况。其与地质分析、示踪剂测试法和岩芯分析等结果综合后,可为油田制订挖潜方案提供依据,达到稳产、增产的目的。将该技术试验性地应用于某油田已经处于中后期生产的某区块,获得了其目标储层的剩余油分布,将之与该区块中试验探测期间各井的含水率分布图对比分析后发现,利用垂直线源电成像技术获得的剩余油分布是可靠的,可为油田中后期挖潜方案的制订提供可靠依据,具有巨大的应用潜力。

THE DISTRIBUTION OF RESIDUAL OIL SATURATION OBTAINED BY RESISTIVITY TOMOGRAPHY WITH A VERTICAL LINE CURRENT SOURCE

A metal cased well is chosen as the current electrode of resistivity tomography with a vertical line current source (RTVLCS), which greatly deepens the depth detection of resistivity tomography and improves the resolution of resistivity tomogram. RTVLCS can be carried out during the course of oil production, and using the apparent resistivity data acquired by this technique and inverse computation, the true resistivity of a target layer can be obtained, then the distribution of residual oil saturation via the relationship of resistivity and oil (or water) saturation. Analyzed our result with these from geological analysis, tracer detection method and rock core analysis and so on, it could provide an important reference for drawing up a plan of oil production. At last the goals of stable and increasing oil production can be achieved. In the present paper, RTVLCS has been tested in a mid-or post-phase oil region of an oilfield, and the distribution of residual oil saturation in its target stratum has been obtained. Compared this result with the distribution of the observed water saturation of each well in the oil region during the course of the measurement of resistivity tomography, it is found that the residual oil saturation obtained by this technique is reliable, which can be taken as the important reference of drawing up a plan for oil production in the mid-or post-phase of an oilfield. Therefore, RTVLCS has great application potentiality.