Investigation of Petrophysical Properties of Butmah Formation (Early Jurassic) Using Well Logs of Selected Wells, Northern Iraq

Section: Research Paper
Published
Jun 24, 2025
Pages
327-342

Abstract

Petrophysical properties of the Early Jurassic Butmah Formation are investigated in three wells (Kand-1, Kd-1; Sheikh Adi-1B, SA-1B; and Shaikan-5B, Sh-5B), in northern Iraq. The data from the well logs are digitized using NeuraLog software, and they were evaluated using Interactive Petrophysics (IP) software. The lithological cross-plots show that the Butmah Formation is mainly comprised of limestone, dolomitic limestone, and dolomite with shale and anhydrite layers. Comparing the wells, it becomes clear that the Butmah Formation in well (Kd-1) has a low effective porosity in the first zone and some depths in the third zone, while it has a higher effective porosity in the first and second zones of wells (Sh-5B) and (SA-1B). Due to the presence of shale, microporosity, and anhydrite cement, the sonic porosity (matrix porosity) has increased at several depth intervals, especially in the (Sh-5B) and (SA-1B) wells. Five permeable zones have been determined based on the permeability curves for the Sh-5B and SA-1B wells. The limited permeability of the Butmah Formation is mostly attributed to the presence of anhydrite cement and shale, whereas the high permeability may be caused by fractures, particularly opened fractures, as well as other factors including the shape and tortuosity of the pores. The presence of shale layers and cement hurts all the petrophysical characteristics in the Butmah Formation, especially in the (Kd-1) well. However, when a reservoir unit is present beneath these beds, they may serve as a good seal or cap. The hydrocarbon saturation (Sh) results from this study show that the (SA-1B) well exhibits high hydrocarbon saturation compared to the (Sh-5B) well.

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How to Cite

Muneeb Al-Dabagh, M., مهى, Sh. Asaad, I., & عرفان. (2025). Investigation of Petrophysical Properties of Butmah Formation (Early Jurassic) Using Well Logs of Selected Wells, Northern Iraq. Iraqi National Journal of Earth Science (INJES), 25(1), 327–342. https://doi.org/10.33899/earth.2024.146079.1218