Abstract The Forties Field, discovered by BP in 1970, is the largest oilfield on the UK Continental Shelf. It is trapped in a simple four-way dip closure, with a Paleocene turbidite sandstone reservoir. The Forties Field originally contained between 4.2 and 5 billion bbl of oil, with 2.75 billion bbl produced to June 2017. Production has been supported by water injection and the influx of a regional aquifer. The original development contained equally spaced producers with peripheral injectors. As the field matured, production was concentrated in the crestal parts of the field with injectors tending to be moved upflank. With the development of seismic lithology prediction and fluid detection, together with 4D seismic technology, it became possible in the late 1990s to target bypassed oil in unexpected locations throughout the field. In 2003, BP sold the field to Apache who were able to rejuvenate production, adding over 170 MMbbl oil reserves, with an extended drilling campaign targeting bypassed pay identified using seismic technologies. Production at the Forties facility has been further enhanced by the development of four satellite oilfields, Bacchus (Jurassic reservoir), Brimmond, Maule and Tonto (Eocene reservoirs), together with Aviat (Pleistocene reservoir) produced for fuel gas supply.

Abstract The Beryl Field is one of the largest oil fields in the UK Continental Shelf. Mobil commenced production in 1976 via the Beryl Alpha platform. Production peaked at approximately 200 000 BOE/day in 1993 before declining to around 50 000 BOE/day in 2012. Apache assumed operatorship in 2012 and, along with partners Shell, has arrested and reversed production decline on platform production through investment in 3D seismic data, drilling, workovers and improvements to operational efficiency. Redevelopment to date by the Beryl area partnership has focused on strategic wells across multiple play types and fields. These wells have realized an 88% success rate and have led to the delineation of additional, lower risk, drill locations. Drilling flexibility, a deep target inventory and effective partner relationships help to expedite the most valuable opportunities and maintain the drilling campaign. In the future, production growth is anticipated through cost-effective developments of new and existing near-field opportunities, including the recently discovered Callater Field with first oil planned in 2017. Three case studies will illustrate: the importance of structural compartmentalization in under-developed fields; the opportunities remaining in mature fields as a result of historical field management practices; and the value of near and new field opportunities for extending field life.