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Research Paper | Engineering Science | Libya | Volume 12 Issue 10, October 2023

Facies Analysis of Middle Ordovician Hawaz Formation and the Major effect of the Ichnofacies on the Reservoir Quality, an Example from the NC115 Block in Murzuq Basin, Southwestern Libya

Alsedik Abousif | Moustfa Abdullah | Alsharef A. Albaghdady | Sadeg Ghnia

Abstract: The Hawaz Formation in Murzuq Basin is an important part of the lower Paleozoic terrigenous Al Gargaf siliciclastic group. The formation was thoroughly investigated, described, and classified as a petroliferous reservoir at the NC115 Block. That was sourced and sealed at the same time by lower Silurian Tanezzuft hot and cold shales. The cored portion of the H27 well was used to define the ichnofacies and other diagenetic characteristics of the Hawaz Formation. Also, forty 1-inch core plug samples were utilized to examine the porosity and permeability and eight thin sections used for the petrographic investigation. Separate litho-and ichnofacies analyses were used to identify the various facies of the Hawaz Formation of the H27 well. Based on facies analysis and lithological and ichnological properties, the examined Hawaz Formation may be classified into bioturbated and nonbioturbated facies. The bioturbated facies include the proximal Skolithos, Skolithos, and Cruziana ichnofacies, while the nonbioturbated facies are sandstone cross-bedding and heterolithic facies. These ichnofacies have been deposited at broad depositional settings from the proximal fluvial-tidal channels to the transitional shoreface offshore environment. The sandstone was classified as quartz arenite and showed a similarity in porosity (up to 25%) for both cross-bedding and proximal Skolithos ichnofacies. Also, the measured porosity from core plugs was around 10 to 20%. However, the nonbioturbated facies was impermeable (up to 6 mD) as compared to the cross-bedding facies, which ranged between 88 and 948 mD.

Keywords: Hawaz Formation, Facies Analysis, Ichnofacies, Skolithos ichnofacies, Cruziana ichnofacies, porosity, permeability

Edition: Volume 12 Issue 10, October 2023,

Pages: 952 - 962