Simple analytical interpretation of single well chemical tracer (SWCT) is possible if one assumes uniform oil saturation, negligible hydrolysis during injection and production and assuming similar dispersion for all reservoir layers. In complex reservoir settings, including multilayer test zones, drift, cross-flow etc., reservoir simulation tools, capable of handling the hydrolysis reaction are commonly applied (Jerauld et al., 2010; Skrettingland et al., 2011). In practice, coupled flow and chemical reaction simulators (see e.g. CMG, 2010; and UTCHEM, 2000) are used. Such coupled simulations are CPU-demanding enough that execution time may be an issue, especially when small grid-size are applied to avoid numerical smearing.