Characteristic Study On Oil-water Replacement Technology For SDPSO Platform Oil Tank System

Combining the structure of Spar platform,drilling-production-storage abilities of FDPSO platform and oil-water replacement technique,the incorporate technique of SDPSO platform bring down the development cost of deepwater marginal oil field.Mass and heat transfer problems are systematically studied in SDPSO platform oil tank concerning Oil-water replacement.In order to explore the scale effect of oil-water replacement oil tank model for SDPSO platform,parameter ? that describing the diffusion intensity of crude oil in water was defined to conduct shrinkage scale design for experimental study.Three kinds of crude oil and three scale models were performed to simulate 33 times uninterrupted oil-water replacement in the laboratory.The study found that model scale contraction does strengthen crude oil mass transfer to the sea water and heat transfer to the outer of bulkhead,generating negative effects on oil-water replacement.This effect mainly reflects the following aspects,the average oil concentration in discharged water is not related to density of oil,but negative to the model scale,and positive to the content of asphaltene in the oil that heavier than the seawater.According to the production practice,it was measured that the thickness of oil-water interface was lower than 1% of tank height.Through filtering and partial derivatives of uploading temperature data,the heat flux of oil water interface is compared in different moment and scale models.Combing measurement of interface thickness,observation of oil-adhering on the bulkhead and process of temperature data,it was validated that the model scale amplification of high solidifying point oil experiment contributed to the severe oil-adhering on the bulkhead.Considering the fluid-solid coupling of closed pipes(solid zone)and oil-water(fluid zone),the simulation researches heat transfer laws in virtue of cloud picture analysis,thermal loss calculation and secure flexible cubage calculation etc.Resulting from the arrangement form of the closed pipes,the average temperature of solid zone in 45° axis clip is greater than that in 0° axis clip,but the average temperature of fluid zone is contrary.By the end of storage,the average temperature of marine area is nearly invariable,the secure flexible cubage of which temperature is 10? than condensation point is 76.88%.The thermal loss model of moving wall in oil and water displacement is deduced by thermal equilibrium theory,and the transient data of Fluent and the post-processing function of cfd-post are incorporated to calculate the thermal loss.During the process of storage,thermal loss of wall is 97.51% and thermal loss of oil-water interface is 2.49% based on oil system,thermal loss of wall is 99.95% based on oil tank system.Based on the result of 1:102 scale model heat transfer simulation,parameters that not involved in laboratory experiment were studied.Combing the distinction of thermal loss curve,the maximum time of lowering inlet temperature and the minimum time of heating up are given.Reasonable storage time is proposed referring to the secure cubage changement curve.Temperature field can be improved by enhancing uploading speed or increasing the contraction scale.