A New Semi utomatic PVT Apparatus for Characterizing Vapex Systems

摘要

Knowledge of fluid properties is critical to the design ofrnVapex projects and other enhanced oil recovery processes thatrnuse solvent vapor extraction, yet very few pertinent data existrnin the published literature. This paper describes a newrnapparatus for the efficient and accurate measurement of thernphysical and phase behaviour properties of mixtures of heavyrnoils and solvents such as propane and butane. The apparatusrncombines advanced capabilities that make it superior tornconventional designs: The automated functions improve thernspeed at which the data are acquired and reduce operator error.rnInline density and viscosity measurements add the capabilityrnof multi-phase detection. High-pressure filtration permitsrnmeasurement of asphaltene and wax precipitation at reservoirrnconditions. Dual gasometers allow accurate measurements ofrngas solubility over a wide range of solvents and reservoirrnpressures. Sub-ambient temperature control makes it suitablernfor Canadian operations.rnThe apparatus was tested against published measurements forrnthe n-hexadecane–carbon dioxide system, and then used torngather a comprehensive suite of data at two isotherms for arnLloydminster heavy oil–propane system. Random scatter inrnthe resulting data was very small. The equipment is wellrnsuited to the acquisition of fluid property measurements forrnboth field design and correlation purposes.rnWith the improvements in both the precision of measurementsrnand the speed of operation offered by the new equipment, itrnwas possible to test some assumptions used in measuringrnvapor–liquid equilibrium in heavy oil–solvent systems. Thernresults suggested that a noticeable uncertainty may bernassociated with conventional methods used to determinernsaturation pressures in these systems.