Aqueous and Petroleum Fluids Associated with Sand Injectites Hosted by Lacustrine Shales from the Oil-Shale Group (Dinantian), Midland Valley, Scotland
Published:January 01, 2007
R. Jonk, D. Duranti, A. Hurst, J. Parnell, A. E. Fallick, 2007. "Aqueous and Petroleum Fluids Associated with Sand Injectites Hosted by Lacustrine Shales from the Oil-Shale Group (Dinantian), Midland Valley, Scotland", Sand Injectites: Implications for Hydrocarbon Exploration and Production, Andrew Hurst, Joseph Cartwright
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Field and diagenetic studies of injected sandstones occurring within the Dinantian oil-shale group of Scotland show that they provided subvertical pathways for petroleum fluid flow from host oil shales. Despite rapid cementation by pre- compactional ankerite, the injected sandstones became reactivated as fluid conduits during subsequent deformation that caused pervasive fracturing. An early phase of Fe dolomite and Fe ankerite veins shows no evidence of petroleum migration; however, abundant primary petroleum inclusions in a second phase of calcite veins, probably formed during Upper Carboniferous to Lower Permian Variscan deformation, suggests that the oil shales had reached maturity. Igneous intrusions...
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Sand Injectites: Implications for Hydrocarbon Exploration and Production
Sand injectites are described in scientific literature as an increasingly common occurrence in hydrocarbon reservoirs, in particular in deep-water clastic systems, where they are known to influence reserves distribution and recovery. Seismically-detectable injected sand bodies constitute targets for exploration and development wells and, subseismic sand bodies provide excellent intra-reservoir flow units that create field-wide vertical communication through depositionally extensive, low-permeability units. As sand injectites form permeable conduits in otherwise low-permeability units they facilitate the expulsion of basinal fluids; hence they act both as a seal risk and mitigate timing and rate of hydrocarbon migration. Injected sand bodies form intrusive traps, which are distinct from structural or stratigraphic traps. Included in this publication are 10 chapters on subsurface examination of sand injectites, 1 chapter on theoretical considerations, and 13 outcrop analogs in reservoirs across the world. Captured in this volume is at least a taste of the global and stratigraphic distribution of sand injectites, and an attempt to introduce readers to sand injectites and their significance in the context of hydrocarbon exploration and production. The book is not intended as a complete review of the field-based literature, but emphasizes high quality case studies from the surface and subsurface. The geographic scope of the book is large, and illustrates the diversity of geological settings in which these fascinating and economically significant features are found.