Subsea Demulsifier Injection to Enhance Crude Oil Production in Offshore Brownfields - A Success Case

In Brazil oilfield scenario, there are large, clearly identified brownfield sites, many of which with high additional oil production potential. The lifting costs and conventional breakeven price per barrel associated with an existing producing field offshore, even those in decline and requiring some recompletion & workover jobs, are – in many situations - less investiment demanding than brand new greenfield development. The formation of water in oil (W/O) emulsions is ubiquitous in oilfield production. As the water commingled in crude increases, the emulsions' stability and viscosity also increase, thence generating flow restrictions due to higher friction losses. The subsea demulsifier injection has proven to be an interesting alternative to overcome this flowing constraint in mature wells, thus maximizing the productive capacity of existing brownfields. This paper presents some results and challenges faced to implement the routine of subsea demulsifier injection, from the development of testing protocols to come up with a tailor-made chemical solution, to the hurdles associated to chemical injection through subsea umbilical- and gas lift-lines.