Sequence Stratigraphy of the ABC Formation and Its Hydrocarbon Potential

Abstract

The ABC Formation is a sedimentary unit characterized by diverse depositional systems and stratigraphic complexity that significantly influence hydrocarbon accumulation. This study applies sequence stratigraphic analysis to delineate systems tracts, key chronostratigraphic surfaces, and sedimentary architecture within the formation. Integrating cores, well logs, seismic interpretation, and biostratigraphic data, we identify multiple third- and fourth-order depositional sequences ranging from fluvial-deltaic to shallow marine settings across the study area. High-resolution sequence boundary mapping reveals five distinct sequences (S0–S4), each comprising lowstand (LST), transgressive (TST), and highstand (HST) systems tracts. LST units show deltaic and incised valley facies favorable for reservoir presence, whereas HST units contain transgressive shales acting as effective seals. Petrophysical evaluation indicates that LST sandstones have porosities of 12–18% and permeabilities of 5–50 mD, with net-to-gross ratios between 0.4 and 0.6. Structural framework analysis via 3D seismic shows subtle faulting and rollover anticlines providing structural traps. Hydrocarbon potential evaluation, including volumetric estimates, indicates formation-level recoverable resources between 200 and 500 million barrels of oil equivalent (MMBOE). Our sequence stratigraphic framework underscores the importance of temporal-spatial facies distribution in prospect delineation. The study concludes that the lower two sequences (S0, S1) hold the greatest development potential due to better reservoir quality and sealing capacity. The proposed model supports risk-informed exploration and improved field development strategies in similar stratigraphic plays globally.