Optimized water quality injection strategy for reservoir pressure support

摘要

A method for supporting the pressure of a subsea hydrocarbon reservoir comprising: recovering produced fluid from the reservoir; separating produced water from the produced fluid; providing seawater; mixing the produced water and the seawater at a determined ratio in order to provide mixed water having a desired temperature; and injecting the mixed water into the subsea hydrocarbon reservoir. Provides a wide range of target temperatures between that of seawater and the produced water. A system for supporting reservoir pressure comprises production 2 wellheads and water 3a and gas injectors connected to an unmanned production platform 9 having processing equipment and a seawater treatment unit 12. A controller controls mixing and reinjection which may account for factors such as the temperature of the reservoir and anticipated produced water flow rate. The ratio and flow rate of mixed waters may change during the process. Provides a way to dispose of produced water and minimise risk of thermal fracking especially in low, temperature, low overburden reservoirs given that produced water is typically heated during separation and processing where heat exchangers are not practicable.