Subsea fluid sampling to maximise production asset in offshore field development

摘要

The acquisition of representative subsea fluid sampling from offshore fielddevelopment asset is crucial for the correct evaluation of oil reserves and forthe design of subsea production facilities. Due to rising operationalexpenditures, operators and manufacturers have been working hard toprovide systems to enable cost effective subsea fluid sampling solutions. Toachieve this, any system has to collect sufficient sample volumes to ensurestatistically valid characterisation of the sampled fluids. In executing theresearch project, various subsea sampling methods used in the offshoreindustry were examined and ranked using multi criteria decision making; asolution using a remote operated vehicle was selected as the preferredmethod, to compliment the subsea multiphase flowmeter capability, used toprovide well diagnostics to measure individual phases – oil, gas, and water.A mechanistic (compositional fluid tracking) model is employed, using the fluidproperties that are equivalent to the production flow stream being measured,to predict reliable reservoir fluid characteristics on the subsea productionsystem. This is applicable even under conditions where significant variationsin the reservoir fluid composition occur in transient production operations. Themodel also adds value in the decision to employ subsea processing inmanaging water breakthrough as the field matures. This can be achievedthrough efficient processing of the fluid with separation and boosting deliveredto the topside facilities or for water re-injection to the reservoir.The combination of multiphase flowmeter, remote operated vehicle deployedfluid sampling and the mechanistic model provides a balanced approach toreservoir performance monitoring. Therefore, regular and systematic fieldtailored application of subsea fluid sampling should provide detailedunderstanding on formation fluid, a basis for accurate prediction of reservoirfluid characteristic, to maximize well production in offshore field development.