Quantitative Description Method Of Residual Oil And Its Application In Water-driven Land Reservoirs With High Water-cut

The study of residual oil distribution is basic to seek potential and enhance recovery .The main oilfields of our country presently are in high water-cut stage and fluid distribution is becoming complex and production is more difficult. Therefore, quantitative prediction of residual oil reserve and residual oil distribution are of significance for oilfield to regulate production, seek potential and enhance ultimate recovery. With the development of reservoir description from macroscopical to microscopical, from qualitative to quantitative, the study of residual oil has began to divert from comprehensive interpretation to fine numerical simulation, log interpretation and calculation of reservoir parameter.Shengli oilfield limited company has developed a series of relative technologies, which are up to the highest domestic level, after the"9.5"and"10.5"research on description technology of residual oil. Based on research of recent years on fine reservoir description and residual oil, this paper studies on and summarizes the main methods of residual oil quantitative description and improves on numerical simulation. At the same time, flow line model method and reservoir engineering calculation method are added to do research and computer automatization of methods are also established in this paper, so they improve the level of residual oil quantitative description.This paper systematically summarizes eight methods of residual oil description, and mainly introduces three methods: reservoir engineering calculation method, flow line model method and numerical simulation method. The paper takes the west of 7 unit in Gudong oilfield as example to make comprehensive correlation analysis on calculation results of three methods, and uses production performance data and core data to verify the results, which prove the reliability of these methods .To quantitatively descript residual oil, reservoir engineering methods are not only used to calculate residual oil indexes, but also numerical simulation method and flow line model method are used to quantitatively descript residual oil from eight aspects (residual oil saturation, flowable residual oil saturation, recovery percent, residual oil reserve abundance, flowable residual oil reserve abundance, distribution map of residual oil reserve abundance, distribution map of fowable residual oil reserve abundance, residual oil distribution of single layer) and residual oil rich areas are found in which flowable residual oil saturation and flowable residual oil reserve abundance are both high.By comprehensive analysis of residual oil by using reservoir engineering calculation method, flow line model method and numerical simulation method, some measures of enhancing recovery and seeking potential are introduced and significant effects are achieved. In the study on fine reservoir description and residual oil destribrution of the west of 7 unit, 336 measures of new and old well are put forward, including repenetrating and changing production strata, packer plugging, using larger pump, reopening shut-off well, water plugging and profile control. It is estimated that recovery can be enhance by 2.2% and recoverable reserve can be increased by 1.548 million ton.