Sand-injection Structures in Deep-water Sandstones from the Ty Formation (Paleocene), Sleipner Øst Field, Norwegian North Sea
Published:January 01, 2007
Nicholas Satur, Andrew Hurst, 2007. "Sand-injection Structures in Deep-water Sandstones from the Ty Formation (Paleocene), Sleipner Øst Field, Norwegian North Sea", Sand Injectites: Implications for Hydrocarbon Exploration and Production, Andrew Hurst, Joseph Cartwright
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Evidence is presented for the widespread presence of sand injectites in mudstone- prone units in the deep-water sandstones of the Ty formation (Paleocene). Pressure communication throughout the field during production demonstrates that the laterally extensive shale layers in the reservoir are not barriers to cross-flow. Centimeter- scale sand injections are recognized in core, and sedimentary features commonly associated with meter-scale sand injectites are also identified. These remobilized sandstones are interpreted to facilitate fieldwide cross-flow, possibly augmented by subseismic- resolution faulting. Evidence for fault-induced or erosional dissection of the mudstone units is lacking. These injection features are similar in scale and appearance to sand injectites known from other reservoirs.
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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.