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Impact of palaeokarsts on the pinnacle reef reservoirs in the Sirt Basin, Libya

Abdeladim M. Asheibi and Asghar Shams
Impact of palaeokarsts on the pinnacle reef reservoirs in the Sirt Basin, Libya
Petroleum Geoscience (February 2024) 30 (1)


More than 20 pinnacle reefs have been discovered in the SE of the Ajdabiya Trough within Paleocene carbonate sediments, most of which are oil-bearing. However, detailed reservoir characterization and conditions governing oil fill-up in this reef have remained unresolved. The major faults provide paths for significant vertical movement of fluids at the edges of the Intisar reef reservoirs. At the same time, the ongoing karst solution collapse also creates vertical zones for fluid encroachment both outside of and within the productive area of the Intisar reef reservoirs. The seismic data show numerous karst-collapse features up to 300 m in diameter that developed shortly after the final drowning of the Intisar 'B' and 'C' reefs. These karst-collapse features may be the main contributing factor in the escape of hydrocarbons within these reefs, which could explain the high water cuts in the Intisar 'B' and 'C' reefs. However, the porosity of the southeastern part of the Intisar 'A' reef has been significantly improved by fracturing and dissolution, as faults associated with fractures are very common in this part of this reef.

ISSN: 1354-0793
EISSN: 2041-496X
Serial Title: Petroleum Geoscience
Serial Volume: 30
Serial Issue: 1
Title: Impact of palaeokarsts on the pinnacle reef reservoirs in the Sirt Basin, Libya
Affiliation: University of Benghazi, Department of Earth Sciences, Benghazi, Libya
Pages: article petgeo2023-008
Published: 20240229
Text Language: English
Publisher: Geological Society Publishing House for EAGE (European Association of Geoscientists & Engineers), London, United Kingdom
References: 63
Accession Number: 2024-023668
Categories: Economic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. col., geol. sketch maps
N28°40'00" - N29°19'60", E20°30'00" - E21°10'00"
Secondary Affiliation: Heriot-Watt University, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 202414
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