Treatment Fluids To Improve Sea Water Injection

Sea water injection to maintain reservoir pressure is currently practised in several North Sea reservoirs viz: Beryl, Forties, Montrose, Piper and Claymore. Injection wells may be completed wholly in an oil bearing zone (pattern flood case) or partly in an oil bearing or transition zone (peripheral flood case). In either case the rate of water injection is restricted by the presence of crude oil in the pores of the rock particularly in the region immediately around the well. This oil is immobile despite continued water injection. The injection rates can be raised, however, if the oil in this critical region is removed as the conductivity (permeability) of the formation will be increased. Very considerable increases in injection rates were reported by previous investigators who used micellar solutions (complex surfactant solutions) to stimulate wells by residual oil removal.