Publications

Hydrocarbon reservoirs are usually indicated by high resistivity on well log measurements based on the response to fluids in the sediment pore space. However, there are some cases where a productive reservoir has a low resistivity―known as Low Resistivity Pay Zone. A Low resistivity pay zone has a log response based on the nature of the constituent minerals and fluid contained in the reservoir. One of the causes of a low resistivity reservoir is the presence of conductive minerals. This study delves into understanding this phenomenon by making simulations through pseudo-cores that contain magnetite minerals with a volume of 2%, 4%, 6%, 8%, 10%, 15%, 20%, and 25% in total of 17 pseudo-cores and conditionally, formation water saturations of 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. The main parameters are measured and counted against the total resistivity and resistivity of the fluid and each pseudo-core while the porosity is known from petrographic analysis. In addition, these experiments attempt to make corrections to the formation water saturation in each pseudo-core to obtain the true resistivity pseudo-core value. Based on measurement results and data analyses, it can be concluded that the presence of magnetite influences resistivity by decreasing, on average, by 42% the resistivity of a clean sandstone reservoir with porosity of 25% -37%. Resistivity decreases with increasing volume of conductive minerals in the rocks. Additionally, this study concluded that if a rock contains magnetite at 2%, a correction needs to be applied using a regression equation obtained in this study whereby the total value of the resistivity and water saturation decreased gradually.