Beryl Field: geological evolution and reservoir behaviour

Abstract

The Mobil-operated Beryl Field is located in UK Block 9/13. Hydrocarbons are present in Triassic and Jurassic sandstone reservoirs, within a large fault-bounded structural trap. Interaction of sub-perpendicular fault trends determined the geological evolution of this structure and controlled the distribution of the sandstone reservoirs.Hydrocarbon generation and subsequent migration commenced in Paleocene time. Entrapment of these hydrocarbons was influenced by pre-existing geological complexity and reservoir continuity. The distribution of different oil-types and multiple fluid contacts is defined by both structural and stratigraphic compartmentalization. Pre-production, the field reached a state of dynamic equilibrium between influx and leakage of hydrocarbons.Production of oil commenced in 1976. Gas injection and water injection were initiated to arrest pressure decline. Pressure distribution and fluid movement throughout the field’s productive life are strongly influenced by geological controls. Understanding these geological controls has resulted in more effective reservoir management and optimization of the hydrocarbon resource.