Thermal effects on single-well chemical tracer tests for measuring residual oil saturation

The Single-Well Chemical Tracer (SWCT) test for measuring residual oil saturation (S_or) often involves injecting cool fluid containing a reactive tracer into a warm formation. The estimation of S_or using this method depends on the separation between reactant and product tracers. Since the reaction rate is temperature dependent, accounting for the thermal effects may be necessary to obtain reliable results. Inequality conditions have been developed which divide the parameter space of SWCT tests into two regions, depending upon the location of temperature front relative to the tracer bank during the reaction period. In the 'safe' region, the estimated S_or values from isothermal and non-isothermal models are essentially equal. These criteria have been extended to include the effects of over/under-burden layers and intervening shales in layered systems.