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Farrimond P.,Integrated Geochemical Interpretation Ltd. | Naidu B.S.,Cairn India Ltd. | Burley S.D.,Cairn India Ltd. | Burley S.D.,Keele University | And 4 more authors.
Petroleum Geoscience | Year: 2015

The Barmer Basin is a failed continental rift of late Cretaceous-Eocene age in Rajasthan, NW India, containing prolific hydrocarbon resources, with 33 discoveries having been made in the last decade. The basin is predominantly oilprone, although gas discoveries have been made in the deeper parts of the basin. Oils in the Barmer Basin are highly waxy, a result of the lacustrine nature of the source rocks that dominate the sedimentary fill of the basin. Detailed interpretation of the molecular composition of the oils defines three main oil groups that can be related to differing sources. The oils are all distinctively lacustrine in origin, although differing in specific source-facies characteristics. All of the oils are isotopically light, mostly in the -29‰ to -33‰ range. Most oils in the northern Barmer Basin (groups 1A and 1B) are interpreted to have been generated from the Late Paleocene Barmer Hill Formation, an excellent oil-prone source rock with predominantly Type I lacustrine algal and bacterial kerogen. Group 2 oils are subordinate in abundance, occurring only in the southern part of the basin, and are interpreted to be at least partly sourced from the overlying Early Eocene Dharvi Dungar Formation, which is characterized by mixed Type I and Type III kerogen, and attains oil maturity only in the southern basin. Group 3 oils are less common, and are of higher maturity than the Group 1 oils, but also appear to have been generated from the Barmer Hill Formation where it was buried more deeply in the central and southern parts of the basin. However, recognition of probable Mesozoic sediments in subbasins beneath the Tertiary Barmer Basin introduces a further source-rock candidate for the Group 3 oils. A high maturity hydrocarbon charge that is recognized in the gasoline-range hydrocarbons in the Group 2 oils of the southern Barmer Basin may also be from a Mesozoic source rock, or from the Barmer Hill Formation that is much more deeply buried in this part of the basin than in the north, and represents a more mixed oil- and gas-prone source © 2015 The Author(s). Source


Boukouvalas A.,Aston University | Sykes P.,Northumbria University | Cornford D.,Aston University | Cornford D.,Integrated Geochemical Interpretation Ltd. | Maruri-Aguilar H.,Queen Mary, University of London
IEEE Transactions on Intelligent Transportation Systems | Year: 2014

Calibration of stochastic traffic microsimulation models is a challenging task. This paper proposes a fast iterative probabilistic precalibration framework and demonstrates how it can be successfully applied to a real-world traffic simulation model of a section of the M40 motorway and its surrounding area in the U.K. The efficiency of the method stems from the use of emulators of the stochastic microsimulator, which provides fast surrogates of the traffic model. The use of emulators minimizes the number of microsimulator runs required, and the emulators' probabilistic construction allows for the consideration of the extra uncertainty introduced by the approximation. It is shown that automatic precalibration of this real-world microsimulator, using turn-count observational data, is possible, considering all parameters at once, and that this precalibrated microsimulator improves on the fit to observations compared with the traditional expertly tuned microsimulation. © 2000-2011 IEEE. Source


Steeb P.,Leibniz Institute of Marine Science | Krause S.,Leibniz Institute of Marine Science | Linke P.,Leibniz Institute of Marine Science | Hensen C.,Leibniz Institute of Marine Science | And 5 more authors.
Biogeosciences | Year: 2015

Large amounts of methane are delivered by fluids through the erosive forearc of the convergent margin offshore of Costa Rica and lead to the formation of cold seeps at the sediment surface. Besides mud extrusion, numerous cold seeps are created by landslides induced by seamount subduction or fluid migration along major faults. Most of the dissolved methane migrating through the sediments of cold seeps is oxidized within the benthic microbial methane filter by anaerobic oxidation of methane (AOM). Measurements of AOM and sulfate reduction as well as numerical modeling of porewater profiles revealed a highly active and efficient benthic methane filter at the Quepos Slide site, a landslide on the continental slope between the Nicoya and Osa Peninsula. Integrated areal rates of AOM ranged from 12.9 ± 6.0 to 45.2 ± 11.5 mmol m−2 d−1, with only 1 to 2.5 % of the upward methane flux being released into the water column. Additionally, two parallel sediment cores from Quepos Slide were used for in vitro experiments in a recently developed sediment-flow-through (SLOT) system to simulate an increased fluid and methane flux from the bottom of the sediment core. The benthic methane filter revealed a high adaptability whereby the methane oxidation efficiency responded to the increased fluid flow within ca. 170 d. To our knowledge, this study provides the first estimation of the natural biogeochemical response of seep sediments to changes in fluid flow. © Author(s) 2015. Source


Dolson J.,DSP Ceosciences and Associ. LLC | Burley S.D.,Cairn India Ltd. | Burley S.D.,Keele University | Burley S.D.,Murphy Oil Co. | And 9 more authors.
AAPG Bulletin | Year: 2015

The discovery of oil and gas in the Barmer Basin in northwest India was one of the more significant global discoveries in the decade 2001-2010. The basin's presence was suspected from gravity and magnetic data in the late 1980s but not confirmed until 1999 from seismic and drilling. The basin is a lacustrine failed rift. Biostratigraphic data, however, indicate it was intermittently connected to marine waters via either the Cambay Basin, the Kutch Basin, or across the Devikot high, temporarily forming a large, shallow estuary. At least six major tectono-stratigraphic events have caused relative lake level falls and translation of clastic reservoirs basinward. Upward of 6 km (∼20, 000 ft) of Cenozoic and Mesozoic sedimentary rocks have been preserved. Prolific source rocks occur from the Mesozoic through Eocene strata. Tectonically, the basin is divided into a northern and a southern province. The north province continues to undergo inversion and erosion, and has not been buried as deeply as the south. Kinetics of the major source facies in the north are substantially different from those in the south, as well as the present-day and paleo-heat flow. These differences have made the northern part of the basin predominantly an oil province and the southern part a mixed oil and gas province. The prolific Paleocene Fatehgarh Formation contains the bulk of the 7.3 billion barrels of stock tank oil in place (STOIP) identified to date, but other reservoirs from the Mesozoic to the late Cenozoic are common and may yield significant future resource additions. Copyright © 2015. The American Association of Petroleum Geologists. All rights reserved. Source


Farrimond P.,Integrated Geochemical Interpretation Ltd. | Green A.,Integrated Geochemical Interpretation Ltd. | Williams L.,Rockhopper Exploration plc
Petroleum Geoscience | Year: 2015

The Sea Lion Field, lying approximately 220 km north of the Falkland Islands in the northern rift of the North Falkland Basin, contains waxy oil in Lower Cretaceous reservoir sands. The oil is likely to be sourced from Lower Cretaceous lacustrine source rocks lying beneath the reservoir sands. A significant complication in interpreting the geochemical data for the Sea Lion oils comes from their overprinting by leaching of bitumen components (especially biomarkers) from immature organic-rich claystones that are interbedded with the reservoir. Accordingly, best estimates of maturity are obtained from gasoline-range and aromatic hydrocarbons. A higher maturity charge is seen in oils from some of the more western wells, consistent with their higher gas–oil ratios. Basin modelling has shown that the source rocks are more mature to the south of the Sea Lion Field, and the observed differences in oil maturity can be related to sourcing from different parts of this kitchen area and/or different stratigraphic intervals of the source-rock package. Gasoline-range hydrocarbons provide evidence for phase fractionation, with some oils having lost a more volatile fraction whilst others have received additional gas charge. A gas leg in the Beverley and Casper South reservoirs in Well 14/15-4Z appears to have been the original fluid charge, and has not displaced oil, although gas compositions suggest that gas was co-generated with oil, and subsequently separated into two phases, at least in some parts of the field. © 2015 The Author(s). Source

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