Construction of the velocity deviation diagram based on the well survey diagram and NMR to determine precise types of porosity in the Asmari Formation in one of the wells of the Ahvaz oil field

Authors

1 Shahid Chamran University of Ahvaz

2 Tabriz University

Abstract

Complex diagenetic processes cause significant variations in porosity within carbonate reservoirs. Porosity type strongly influences fluid flow and ultimately recoverable hydrocarbons. However, core analysis, the traditional method for porosity determination, is expensive. This study investigates the use of velocity deviation logs, a cost-effective alternative, to identify porosity types in the Asmari Formation. Well log data, including velocity deviation, petrophysical, and NMR logs, were used to classify porosity. Microscopic thin section observations served as validation. The velocity deviation log identified eight porosity subgroups, including intergranular, moldic, microporosity, interparticle, intercrystalline, fracture, and shale microporosity. Results revealed that intergranular porosity in sandstones and fracture, intergranular, and intercrystalline porosity in carbonates control production from the Asmari reservoir. This study demonstrates the effectiveness of velocity deviation logs in determining porosity types within the Asmari Formation and highlights the importance of these four porosity types for reservoir production.
It is hoped that the data of this study will be effective in identifying production zones, optimization and expansion of the studied oil field.

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