TY - JOUR

T1 - Sedimentology and sequence stratigraphy of automated hydraulic flow units – The Permian Upper Dalan Formation, Persian Gulf

AU - Kakemem, Umid

AU - Ghasemi, Mohammadfarid

AU - Adabi, Mohammad Hossein

AU - Husinec, Antun

AU - Mahmoudi, Ayoub

AU - Anderskouv, Kresten

N1 - Publisher Copyright: © 2022 The Authors

PY - 2023

Y1 - 2023

N2 - The Upper Dalan (Khuff-equivalent) Formation constitutes the principal reservoir of the giant gas fields in the Persian Gulf Superbasin. A sedimentological and sequence stratigraphic analysis was conducted on selected cores from the South Pars, Kish, and Lavan gas fields, offshore Iran, to evaluate a recently proposed method for automatic reservoir zonation, and discuss the predictability of such defined zones. The succession consists of nine evaporite-carbonate lithofacies grouped into three shallow-marine facies associations (shoal, lagoon, and tidal flat) that were deposited on a low-gradient homoclinal ramp. Lithofacies are stacked into two complete long-term (3rd-order?) transgressive-regressive depositional sequences. Sequence boundaries were defined by facies stacking patterns and presence of evaporites and meteoric diagenetic features. The reservoir quality was improved by both early-stage dolomitization and dissolution, whereas pervasive pore-filling anhydrite cementation, compaction, and late-stage over-dolomitization reduced the reservoir quality. Whereas dolomitization overall slightly affected porosity, it significantly increased the permeability in mud-dominated lithofacies. Fibrous and bladed calcite rim cements, as well as micritization of the grain-dominated lagoon and shoal lithofacies, prevented porosity reduction during the early- and late-stage burial by building a stronger framework. Core-plug porosity and permeability measurements were used to calculate the Winland R35, Reservoir Quality Index (RQI), and Flow-Zone Indicator (FZI) values. A novel, fully automated approach, was used to effectively identify the hydraulic flow units (HFUs). The HFUs are sedimentologically distinct units with characteristic combinations of the original rock texture and the subsequent diagenetic overprint, and their subsurface position within the sequence stratigraphic framework may be predicted.

AB - The Upper Dalan (Khuff-equivalent) Formation constitutes the principal reservoir of the giant gas fields in the Persian Gulf Superbasin. A sedimentological and sequence stratigraphic analysis was conducted on selected cores from the South Pars, Kish, and Lavan gas fields, offshore Iran, to evaluate a recently proposed method for automatic reservoir zonation, and discuss the predictability of such defined zones. The succession consists of nine evaporite-carbonate lithofacies grouped into three shallow-marine facies associations (shoal, lagoon, and tidal flat) that were deposited on a low-gradient homoclinal ramp. Lithofacies are stacked into two complete long-term (3rd-order?) transgressive-regressive depositional sequences. Sequence boundaries were defined by facies stacking patterns and presence of evaporites and meteoric diagenetic features. The reservoir quality was improved by both early-stage dolomitization and dissolution, whereas pervasive pore-filling anhydrite cementation, compaction, and late-stage over-dolomitization reduced the reservoir quality. Whereas dolomitization overall slightly affected porosity, it significantly increased the permeability in mud-dominated lithofacies. Fibrous and bladed calcite rim cements, as well as micritization of the grain-dominated lagoon and shoal lithofacies, prevented porosity reduction during the early- and late-stage burial by building a stronger framework. Core-plug porosity and permeability measurements were used to calculate the Winland R35, Reservoir Quality Index (RQI), and Flow-Zone Indicator (FZI) values. A novel, fully automated approach, was used to effectively identify the hydraulic flow units (HFUs). The HFUs are sedimentologically distinct units with characteristic combinations of the original rock texture and the subsequent diagenetic overprint, and their subsurface position within the sequence stratigraphic framework may be predicted.

KW - Automated reservoir zonation

KW - Carbonate ramp

KW - Hydraulic flow units

KW - Khuff formation

KW - Petrography

KW - Reservoir characterization

U2 - 10.1016/j.marpetgeo.2022.105965

DO - 10.1016/j.marpetgeo.2022.105965

M3 - Journal article

AN - SCOPUS:85140807910

VL - 147

JO - Marine and Petroleum Geology

JF - Marine and Petroleum Geology

SN - 0264-8172

M1 - 105965

ER -