Application of TDA technique to estimate the hydrocarbon saturation using MRIL Data: A Case study for a Southern Iranian Oilfield

Petrophysical evaluation of petroleum reservoirs is one of the most challenging tasks for hydrocarbon reserve determination. One critical petrophysical parameter is the water saturation which is normally calculated from Archie’s equation. Carbonate reservoirs, however, due to their complex mineralogy are not good candidates for Archie’s equation because Archie’s parameters are strongly dependent on pore pattern distribution, type and distribution of clay content, wettability and mineralogical properties. In the present study, Magnetic Resonance Image Logging (MRIL) was used to determine water and hydrocarbon volumes using Time Domain Analysis (TDA) technique. The results of TDA technique indicated that the water and oil peaks are well separated in the light oil zones and the calculated volumes of hydrocarbon and water by using TDA were in agreement with water and oil saturation calculated from conventional logging measurements. Moreover, values of reservoir oil viscosities were estimated to be less than 10 cps by intrinsic T1. This study shows that MRIL-based interpretation models are easy to apply because they require fewer unknowns as inputs and because MRIL response is not influenced by the resistivity model’s parameters, water salinity, etc.