The Single-Wel l Chemical Tracer Method for Measuring Residual Oil Saturation ———Review and Prospect

A mass of oil that be reserved after primary and secondary recoverying can not be availability recovered. Exploitation is becoming more and more difficult while the newly discoverable petroleum oil is less. New fields were not being discovered fast enough to replace the old ones as they were depleted. It became clear that the oil remaining in our developed reservoirs could be considered a valuable primary resource. The need for determining residual oil saturation (S_OR) has existed.SOR is a critical parameter in the evaluation of the potential for the third recovery. There are a number of recognized methods for estimating remaining oil content of reservoirs and these methods have inherent advantages and limitations. One method which was thought to be further developed was the single-well chemical tracer procedure.The method is developed by Deans in later 1960's. The chromatographic effect was first proposed as a way to measure S_OR by injecting two tracers dissolved in brine into one well, and producing the brine and tracers from a second well nearby. The first laboratory experiments using a chemical reaction to produce a tracer in-situ in a sand pack containing a refined oil at residual saturation has succeeded and the method was applied in fields in 1968. The technology is proprietary to Exxon Production Research Company in 1971.It was applied widely since 1968. One advantage of the single-well method is the larger amount of reservoir volume that is sampled as compared to other methods.This results in a more effective estimate of the S_OR value of the entire reservoir than would be possible by traditional methods.This article review the background,method fields application and further development of the method based on plenty of literature search.Then it look forward to the method's development prospect.