Return to rifts – the next wave: fresh insights into the petroleum geology of global rift basins

Abstract

Rift basin exploration has provided the oil and gas industry with almost one third of discovered global hydrocarbon resources. The maturity of prolific passive margin sequence plays has necessitated a shift in technical emphasis to understanding petroleum geology of the deeper precursor rift basin megasequences. Modelling of these petroleum systems relies extensively on theoretical stretching hypotheses for whole-crust evolution and heat flow prediction. Several alternatives have emerged to account for anomalous rift-related thermal stress, asymmetry of structural styles and origin of thick syn-rift ‘sag-basin’ subsidence patterns at passive continental margins. These observations cannot be predicted by the pure shear uniform stretching model first introduced by McKenzie in 1978. Newly acquired, 2D long cable deep seismic records provide empirical evidence that supports more complex, polyphase, depth-dependent stretching origins for rift-basin formation. Heterogeneities are believed to be inherent in the brittle upper crust, in the ductile lower crust and lithospheric mantle and so result in the complex distribution of accommodation space recorded by syn-rift megasequence deposition during episodes of orthogonal or oblique extension. No single stretching model uniquely describes the varied structural response of the anisotropic crust to plate-scale extension. A hybrid of phased simple and pure shear deformation mechanisms separated by regional lateral, and possibly vertical crustal discontinuities, may explain the apparent paradox of along-strike co-existence of uniform versus depth-dependent stretching structural geometries.

Cross-section restoration and one-dimensional basin modeling of the Central Subbasin in the southern Kunsan Basin, Yellow Sea

“…Rift basins include over 170 of the world's largest hydrocarbon accumulations greater than 500 Â 10 6 barrels of oil or over 3 Â 10 12 ft 3 of gas (Man et al, 2001), comprising about one third of discovered global hydrocarbon resources (Fraser et al, 2007). Many hydrocarbon-rich Tertiary basins in Southeast Asia are continental rift basins (Hall, 2009).…”

Structural differences and exploration potential of basins in the eastern and western branches of the East African Rift System

“…Among the six major types of basins, rift basins are very important hydrocarbon-bearing basins where the oil and gas resources are second only to those in foreland basins and passive margin basins, and they are the most active areas of hydrocarbon exploration in the world (Dou and Wen, 2021;Dou et al, 2011;Fraser et al, 2007;Wen et al, 2012aWen et al, , 2014Yu et al, 2010;Zhang et al, 2018Zhang et al, , 2020. The East African Rift System (EARS), which is located in the East Africa, is currently the youngest group of Cenozoic intracontinental rift basins in the world.…”

The Early Cambrian Mianyang-Changning Intracratonic Sag and Its Control on Petroleum Accumulation in the Sichuan Basin, China

“…They account for ∼30% of global hydrocarbon discoveries [1]. In particular, the Neoproterozoic assembly and break-up of two supercontinents, that is, Rodinia and Greater Gondwana, were marked by the development of a long series of rift valleys, half-graben, pull-apart basins, and intramontane molasse basins, along the Peri-Gondwanan Margin, from Australia through Pakistan, Oman and North Africa, and South China block (Figure 1(a)) [2,3].…”