Reservoir evaluation using partitioning tracer

摘要

Reservoir information for determining residual oil saturation is obtained by injection of a partitioning tracer and a non-partitioning material through an injection well and periodically logging a second well spaced from the injection well to determine time of passage and amount of said injected materials. A preferred partitioning tracer is iodoethanol containing iodine 131, and the second material may be a radioactive tracer having a gamma ray emission spectrum different from the partitioning tracer or it may be a brine having a salinity different from that of formation water in the reservoir.