Earth Sciences Pakistan (ESP)

UNDERSTANDING THE GAMMA RAY LOG AND ITS SIGNIFICANCE IN FORMATION ANALYSIS

May 23, 2024 Posted by Natasha In Earth Sciences Pakistan (ESP)

ABSTRACT

UNDERSTANDING THE GAMMA RAY LOG AND ITS SIGNIFICANCE IN FORMATION ANALYSIS

Journal: Earth Sciences Pakistan (ESP)
Author: Collins O. MoluaThis is an open access article distributed under the Creative Commons Attribution License CC BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Doi: 10.26480/esp.02.2024.55.60

Gamma-ray log interpretation is an exploration technique that provides significant information about lithology, mineral constituents, pore size, and water content during oil and gas exploration. This study uses gamma-ray log analysis to identify lithology, discriminate faults and fractures, and estimate water saturation and porosity in the Nigerian petroleum region. We acquired gamma-ray logs using specialized logging equipment fitted with scintillation detectors. The raw data was processed and calibrated to obtain gamma-ray values in API units. Interpretation involved comparing measured values to standard shale and sandstone references, identifying lithological changes, and identifying potential reservoir locations. Gamma-ray logs were combined with other well logs, such as resistivity, neutron, and density, for comprehensive formation evaluation. The analysis of gamma-ray logs in Nigerian oil fields revealed promising results. Higher gamma-ray readings effectively distinguished shale-rich intervals (up to 96.234 API units at 143.123 meters depth) from potential hydrocarbon-bearing zones. Clean sandy areas with low gamma-ray values (65.432 API units at 100.234 meters depth) indicated high porosity and permeability reservoirs. Variability in gamma-ray trends across depth intervals (ranging from 4.567 to 9.567 API units) suggested lithological changes and stratigraphic boundaries. Gamma-ray log analysis has proven invaluable in the Nigerian oil and gas industry. It contributes to well depth identification, defining zones with shale potential, exploring hydrocarbon reservoirs and mapping stratigraphic layers, as well as optimizing post-well development plans. The fusion of gamma-ray logs with other well logs will help one have a deeper understanding of the subsurface geological characteristics. Determining how to manage resources for development and sustainability requires this understanding.

Pages 55-60
Year 2024
Issue 2
Volume 8

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