Design of a Single-Well Wettability Tracer Test in the Sulimar Queen Reservoir

A single-well wettability tracer test (SWWTT) was designed with The University of Texas at Austin Chemical Flooding Simulator (UTCHEM) and an in-situ test based on this design was performed in the Sulimar Queen Reservoir. Wettability controls distribution and characteristics of the flow of fluids through a reservoir rock. A sensitivity study was done on the design that involved different relative permeability models. A SWWTT consists of the injection of either a brine slug followed by a brine buffer, or an oil slug followed by an oil buffer or both depending on what is needed to cause two phase flow in the reservoir near the injection well. The slugs contain material balance (non-reactive) tracers and reactive tracers. After injection there is a shut-in time to allow the reactive tracers to react with the water and form product tracers. The same well is produced and the tracer concentrations measured along with phase cuts and optionally bottomhole pressure. The sensitivity study showed that both the water slug and buffer could be eliminated because of high initial water saturation in the Sulimar Queen Reservoir. The reactive tracers used were ethyl formate and propyl formate with their product tracers ethanol and n-propanol, respectively. A core flood experiment was done to prepare for the field test. The in-situ test involved injecting 10 STB of oil preflush, then a 40 STB oil slug with reactive tracers, and a 10 STB oil buffer was injected into the formation. Both the reactive and product tracers were then produced back in the same well and analyzed after they had hydrolyzed by half in the formation. The information obtained from the test was used to estimate the in-situ relative permeabilities of the formation by history matching with UTCHEM. The results of the history match indicated that the reservoir was mixed-wet.Petroleum and Geosystems Engineerin