The Driftpile deposit is hosted by fine-grained carbonaceous black siliciclastic rocks of the Middle to Late Devonian Lower Earn Group, in a series of imbricate northeastward-verging thrust panels. Mineral assemblages consist of two distinct facies occupying two
different stratigraphic positions - a localized, lower sulphide-carbonate facies and a laterally extensive upper barite (±sulphides) facies. The footwall is massive mudstone or siliceous to cherty carbonaceous argillite interbedded with radiolarian-rich chert and locally with cryptic pyrite
laminated mudstone. Hanging wall rocks are turbidite lithofacies overlain by concretionary shale and nodular mudstone. This stratigraphic sequence with two cycles of mineralization, each preceded by a period of anoxic, starved sedimentation and succeeded by an influx of turbidites, represents an
interplay of mineralizing and tectonic events, with discrete episodes of faulting triggered the release of metalliferous basinal brines into anoxic bottom waters and then the sudden and rapid influx of turbidites.
The Clipper Gas Field is a moderate-sized faulted anticlinal trap located in Blocks 48/19a and 48/19c within the Sole Pit area of the southern North Sea gas basin. The reservoir is formed by the Lower Permian Leman Sandstone Formation, lying between truncated Westphalian Coal Measures and the Upper Permian evaporitic Zechstein Group which form source and seal respectively. Reservoir permeability is very low, mainly as a result of compaction and diagenesis which accompanied deep burial of the Sole Pit Trough, a sub-basin within the main gas basin. The Leman Sandstone Fm. is on average about 715 ft thick, laterally heterogeneous and zoned vertically with the best reservoir properties about the middle of the formation. Porosity is fair with a field average of 11.1%. Matrix permeability, however, is less than 1 millidarcy on average and is so low that some intervals in the field will not flow gas unless stimulated. Steep dipping zones of natural fractures occur in certain areas of the field; these commonly allow high flow rates to be achieved from large blocks of low-permeability matrix. Expected recoverable reserves from the most favourable part of the field are 558 BCF and Clipper Field is now being developed in conjunction with part of the adjacent Barque Gas Field. Later development of the remainder of Clipper Field will depend upon reservoir performance in the initial development area. Fig. 1. Top Rotliegend structure map based on 2-D seismic data showing position of initial development area, line of structural section and seismic line.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.