Paleoenvironmental reconstruction, sequence stratigraphy and reservoir quality of Lower Cretaceous sequences (Kazhdumi Formation) in the northwest of the Persian Gulf

Authors

1 School of Geology, College of Science, University of Tehran

2 School of Geology, University college of Science, University of Tehran

Abstract

This study aims to investigate the control of facies characteristics and depositional environments on the distribution of reservoir parameters in the Kazhdumi reservoir formation in one of the fields in the northwest of the Persian Gulf. This formation is composed of fine- to medium-grained sandstones, mudstone, calcareous shales, and limited carbonate sequences, and consists of eight sedimentary facies., The Kazhdumi Formation is divided into two sections: the lower and upper parts. The lower section, composed of a thick sequence of high-quality sandstones, constitutes the most significant reservoir horizon. The sandstones in the upper part of this formation also have notable reservoir significance. In this study, a comprehensive dataset including core samples, plugs, and thin-section petrographic analyses, along with porosity-permeability data, were utilized to evaluate the reservoir quality. Based on the described facies, the depositional environment of the Kazhdumi Formation is interpreted as a deltaic to open marine setting. Sequence stratigraphy analysis was conducted using the transgressive-regressive method and the Exxon sequence stratigraphy model. To assess reservoir quality, methods such as reservoir quality index determination, Winland rock type classification, and modified Lorenz plot were employed. It was ultimately determined that the medium- to coarse-grained, well-sorted, matrix-free sandstone facies in the lower part of the Kazhdumi Formation created the best reservoir horizons. These facies, due to early oil migration and high sedimentation rates, underwent minimal diagenesis and remain loosely consolidated to semi-consolidated, correlating with the lowstand systems tract in the sedimentary sequence of the Kazhdumi Formation.

Keywords



Articles in Press, Accepted Manuscript
Available Online from 08 October 2024
  • Receive Date: 21 July 2024
  • Revise Date: 07 October 2024
  • Accept Date: 08 October 2024