Awali (Bahrain) – Large (9.5 BBO, 10.4 TCF in place), multi-reservoir field with hydrocarbons ranging from tar to lean gas in >22 reservoirs of Cretaceous, Jurassic and Permian age. Onstream since 1932 and still producing today. The most important producer is the Mauddud shallow-marine limestones dominated by moldic, vuggy porosity and variable permeability. Crestal gas injection used Arab gas initially and then lean gas from the deeper Permian Khuff Formation. Production was enhanced by automated cyclical production, infill and horizontal drilling.
Breagh (UK) – gas field, onstream since 2013. Produces from fluvio-deltaic sands of the Lower Carboniferous Yoredale Formation. Initial poor well flow rates due to lower-than-expected permeability (0.01-100 mD) suggested the field was uneconomic. However, the use of highly deviated sidetracks and S-shaped wells to maximise reservoir exposure and hydraulic fracture stimulation led to improved production rates.
Noble (USA) – Multi-reservoir oil field, onstream since 1937, with production mainly from Middle Mississippian fluvial valley-fill sandstone through solution-gas and aquifer drive, aided by waterflood and horizontal drilling.
Urengoy (Russia) – Multi-reservoir gas and oil field, onstream since 1978, with dominantly gas production from Upper Cretaceous fluvial, deltaic, shoreface and barrier bar sandstones by gas-expansion and weak aquifer drive, aided by selective perforation, sand control and hydraulic fracturing.
Wertz (USA) – Onstream since 1920, the main Pennsylvanian, layered aeolian-dune, light-oil sandstone has been produced by gravity drainage and moderate aquifer drive, aided by hydrocarbon gas injection, waterflood, and CO2 WAG miscible flood, reaching a >60% recovery factor.
Yushuling (China) – Multi-reservoir oil field, onstream since 1991, with production mainly from thin and low-permeability Lower Cretaceous fluvial-lacustrine delta sandstones under solution-gas drive through phased development by waterflooding, aided by infill/step-out drilling, horizontal drilling and hydraulic fracturing.