The value of fieldwork in making connections between onshore outcrops and offshore models: an example from India
Andy Racey, John Fisher, Haydon Bailey, Sandip Kumar Roy, 2016. "The value of fieldwork in making connections between onshore outcrops and offshore models: an example from India", 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
Download citation file:
Fieldwork provides an efficient and economical way of obtaining genuine geological data that can be used to constrain, test and develop exploration models in frontier areas. This study of the Cretaceous outcrops of NW India has been used to characterize models for petroleum systems postulated to have developed beneath the Deccan volcanic sequence, offshore western India, where well data are not available. To date, exploration of ‘sub-Deccan plays’ has mainly been limited to the NW, where the presence of a working Cretaceous petroleum system has been proven in the offshore Kutch Basin.
A revised chronostratigraphic framework has been defined for the Cretaceous section as a result of new biostratigraphic data collected during this study and a thorough revision of existing palaeontological data. The revised framework, together with lithofacies observations from the field, has provided a basis for regional sequence stratigraphic correlation, which has been used to link data from onshore outcrops to models of offshore petroleum systems.
A Lower Cretaceous clastic package that, in part, corresponds to the Lower Goru and Bhuj Formation reservoirs of the Indus Basin of Pakistan and the Kutch Basin in India has been correlated across the region. Towards the top of this package, a transition from fluvial to shallow-marine sedimentation marks the onset of a marine transgression that reaches its peak in the Turonian. Marly limestones and claystones associated with this regionally mapped event are a potential topseal to the Lower Cretaceous clastic package. Geochemical evaluation of several outcrop locations has identified potential source-prone facies that, if present downdip in the offshore, may provide a mechanism for charging a pre-Deccan play.
Figures & Tables
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.