--> Analysis Of Magnetite Mineral Influence On Clean Sandstone Reservoir Resistivity Through Correction Methods In Low Resistivity Pay Zone

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Analysis Of Magnetite Mineral Influence On Clean Sandstone Reservoir Resistivity Through Correction Methods In Low Resistivity Pay Zone

Abstract

Abstract

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.