Eocene carbonate microfacies distribution of the Chorgali Formation, Gali Jagir, Khair-e-Murat Range, Potwar Plateau, Pakistan: approach of reservoir potential using outcrop analogue

Awais, Muhammad; Hanif, Muhammad; Jan, Irfan U.; Ishaq, Muhammad; Khan, Muhammad Younis

doi:10.1007/s12517-020-05377-9

Cited by 5 publications

(1 citation statement)

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“…42 About 150 exploratory wells have been drilled in the area; many were prematurely abandoned because of structural complexity. 40 Studies conducted elsewhere 43 44 suggested that the distributions of porosity and permeability in Eocene carbonates are controlled by depositional, diagenetic, and deformational processes. According to Wrobel-Daveau and Barracloughy, 45 validation of reservoir properties in the Potwar Basin, particularly for the Eocene Sakesar Limestone, is key to success.…”

Section: Geological Settingsmentioning

confidence: 99%

Carbonate Reservoir Quality Variations in Basins with a Variable Sediment Influx: A Case Study from the Balkassar Oil Field, Potwar, Pakistan

Amjad

Ehsan

Hussain³

et al. 2023

ACS Omega

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The carbonate reservoir quality is strongly reliant on the compaction process during sediment burial and other processes such as cementation and dissolution. Porosity and pore pressure are the two main factors directly affected by mechanical and chemical compactions. Porosity reduction in these carbonates is critically dependent on the overburden stress and subsidence rate. A variable sediment influx in younger basins may lead to changes in the reservoir quality in response to increasing lithostatic pressure. Deposition of molasse sediments as a result of the Himalayan orogeny caused variations in the sedimentation influx in the Potwar Basin of Pakistan throughout the Neogene times. The basic idea of this study is to analyze the carbonate reservoir quality variations induced by the compaction and variable sediment influx. The Sakesar Limestone of the Eocene age, one of the proven carbonate reservoirs in the Potwar Basin, shows significant changes in the reservoir quality, specifically in terms of porosity and pressure. A 3D seismic cube (10 km2) and three wells of the Balkassar field are used for this analysis. To determine the vertical and lateral changes of porosity in the Balkassar area, porosity is computed from both the log and seismic data. The results of both the data sets indicate 2–4% porosities in the Sakesar Limestone. The porosity reduction rate with respect to the lithostatic pressure computed with the help of geohistory analysis represents a sharp decrease in porosity values during the Miocene times. Pore pressure predictions in the Balkassar OXY 01 well indicate underpressure conditions in the Sakesar Limestone. The Eocene limestones deposited before the collision of the Indian plate had enough time for fluid expulsion and show underpressure conditions with high porosities.

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