Deepwater Turbidite Lobe Deposits: A Review of the Research Frontiers

Abstract

Deepwater/deep‐marine turbidite lobes are the most distal part of a siliciclastic depositional system and hold the largest sediment accumulation on the seafloor. As many giant hydrocarbon provinces have been discovered within deepwater lobe deposits, they represent one of the most promising exploration targets for hydrocarbon industry. Deepwater exploration is characterized by high cost, high risk but insufficient data because of the deep/ultra–deepwater depth. A thorough understanding of the deepwater turbidite lobe architecture, hierarchy, stacking pattern and internal facies distribution is thus vital. Recently, detailed outcrop characterizations and high–resolution seismic studies have both revealed that the deepwater lobe deposits are characterized into four–fold hierarchical arrangements from “beds”, to “lobe elements”, to “lobes” and to “lobe complex”. Quantitative compilations have shown that hierarchical components of lobe deposits have similar length to width ratios but different width to thickness ratios depending on different turbidite systems. At all hierarchical scales, sand–prone hierarchical lobe units are always separated by mud–prone bounding units except when the bounding units are eroded by their overlying lobe units thus giving rise to vertical amalgamation and connectivity. Amalgamations often occur at more proximal regions suggesting high flow energy. A mixed flow behavior may occur towards more distal regions, resulting in deposition of “hybrid event beds”. These synthesized findings could (1) help understand the lobe reservoir distribution and compartmentalization therefore benefit the exploration and development of turbidite lobes within the deep marine basins (e.g. South China Sea) and (2) provide rules and quantitative constraints on reservoir modeling. In addition, the findings associated with deepwater turbidite lobes might be a good starting point to understand the sedimentology, architecture and hierarchy of turbidites in deep lacustrine environment.

Thickening-upward cycles in deep-marine and deep-lacustrine turbidite lobes: examples from the Clare Basin and the Ordos Basin

“…Compared to the interpretation of sandy debrites, turbidites resulted from turbidity flows can be better predicted in terms of organization patterns (as demonstrated in this study) and quantitative dimension (e.g. Zhang et al 2017b;Cullis et al 2018). This could benefit future exploration and development in deepmarine and deep-lacustrine deposits, for both conventional and unconventional reservoirs.…”

3D modeling of deepwater turbidite lobes: a review of the research status and progress

“…The lobe hierarchical units are well separated by fine-grain units which are termed interlobe, inter-lobe element and inter-bed, respectively. This fourfold hierarchical scheme has been widely applied with slight modifications in recent literature on turbidite lobes from different systems (e.g., Marini et al 2011Marini et al , 2015Zhang et al 2017) and is adopted tout court in the present paper.…”

Deep-water depositional architecture and sedimentary evolution in the Rakhine Basin, northeast Bay of Bengal

“…The updip contact between frontal splays and channels is transitional or unclear. We found it more convenient to put the end members of frontal splay geometries as either elongate frontal splays (for thinner, more extended frontal splays fed by narrow channels) or clustered frontal splays (for radial or lobate geometries) (Zhang et al 2017a). More elongate frontal splays appear to be more intimately associated with channels which are narrow and bordered by a 'double-track' of higher amplitudes, and they are often more sinuous channels than the clustered frontal splays.…”