Outcrop analogues for hydrocarbon reservoirs in the Columbus Basin, offshore east Trinidad
Andrew Bowman, 2016. "Outcrop analogues for hydrocarbon reservoirs in the Columbus Basin, offshore east Trinidad", The Value of Outcrop Studies in Reducing Subsurface Uncertainty and Risk in Hydrocarbon Exploration and Production, M. Bowman, H. R. Smyth, T. R. Good, S. R. Passey, J. P. P. Hirst, C. J. Jordan
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The Mayaro Formation, which is exposed in SE Trinidad, is the key outcrop analogue for prolific hydrocarbon reservoirs in the Columbus Basin, offshore east Trinidad, because it was deposited in the same basin setting by the same depositional system (the palaeo-Orinoco) as the offshore reservoirs. Sequence and parasequence stacking patterns affect the distribution of different types of reservoir sand bodies and heterogeneities, with the potential to influence fluid flow in subsurface hydrocarbon reservoirs. Spectacular outcrops of successions of storm-wave-influenced sand bodies, tens to hundreds of metres thick, deposited in axial and medial delta-lobe settings are characterized by high sand–shale ratios (0.7–>0.95), and are analogues for many producing reservoirs in the basin. Fluvial- and tide-influenced sand bodies deposited in distal distributary settings are also recognized in the outcrops, but may be difficult to distinguish from medial delta-lobe deposits in subsurface data. More complex, thinly bedded distal delta-lobe deposits, with subsurface reservoir potential, exhibit lower sand–shale ratios (0.3–0.6). Complex depositional architectures, with a high proportion of thinly bedded sandstones, also occur in association with delta-front deposits. The distal delta-lobe and delta-front deposits are analogous to some of the most challenging to develop reservoirs in the Columbus Basin.
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The Value of Outcrop Studies in Reducing Subsurface Uncertainty and Risk in Hydrocarbon Exploration and Production
Field studies over a range of scales have been important in the upstream oil and gas industry for decades. Advances in digital outcrop characterization and data capture, coupled with increased computational capabilities, have resulted in a resurgence in fieldwork; these field studies are required to develop depositional, stratigraphic and structural concepts and provide the data which underpin the current generation of complex, computer generated, 3D subsurface models. These models provide an informed means of benchmarking the subsurface along with a more considered view of subsurface uncertainty and management of the risks identified. The papers in this volume cover safety in the field, frontier basin petroleum system assessment, field appraisal and development including unconventional resources, applications of techniques such as LiDAR and 3D photogrammetry, and uncertainty characterization. The studies were undertaken in diverse locations such as the Faroe Islands, Italy, Algeria, India, the USA and Trinidad; they represent a range of tectonic settings and a wide geological time frame. The spectrum of papers is testament to the value and integral position that fieldwork occupies within the modern hydrocarbon industry.