oa Field Case: The Origin of the Fluid Properties Variation and the Tar Mat

In this work, a field case will be presented to induce discussion on the relevance of the data to be acquired and to be analyzed according to the objectives of the investigation. In the field case presented, a strong segregation was observed in a connected reservoir. The in situ viscosity of the oil varies from less than 1 cPo for samples taken close to the gas cap, to more than 100 cPo for oil sampled 400 meters deeper. “Tar mat deposits” were also observed in the bottom part, but also in some specific area of the reservoir.