The UK’s Oil and Gas Authority (OGA) estimates that there are 3.8 trillion cubic feet (tcf) of remaining accessible gas within the Southern North Sea (SNS) reservoirs, inclusive of infill opportunities, undeveloped discoveries and prospects. The SNS continues to be the UK’s principal gas province and underpins the UK’s indigenous gas supply. The SNS is a mature basin, with first gas in 1967. Over the last 50 years, a total of approximately 40 tcf has been produced. The basin continues to produce almost 1.3 billion cubic feet/day. Crucially, most producing gas fields are connected to working infrastructure, inclusive of offshore compression hubs, export pipelines and onshore terminals.
Oil and gas fields located in the Southern North Sea and adjacent onshore areas.
Reservoirs
The reservoirs of the Southern North Sea are mostly of similar age and type to those found in the East Irish Sea Basin and likewise offer potential stacked play opportunities.
Historically, the principal reservoir in the Southern North Sea has been the renowned and prolific Rotliegend Sandstones. These Permian age sandstones are predominantly composed of aeolian dune, interdune sabkha and fluvial deposits. Porosities and permeabilities can be variable but are generally high. The Rotliegend is underlain by a sequence of Carboniferous age coals and carbonaceous shales, which provides the source rocks, whilst Late Permian Zechstein evaporites form the seal.
Additional, but important reservoirs are the Middle to Upper Permian, Zechstein dolomites, overlying Bunter Sandstones of Triassic age and the underlying Upper Carboniferous sandstone sequences.