MICROSCOPIC DISPLACEMENT EFFICIENCY OF ALKANE AND CO2-BASED GASEOUS SOLVENTS WITH HEAVY OIL This paper was prepared for presentation at the International Symposium of the Society of Core Analysts held in Halifax,Nova Scotia,Canada,4-7 October,2010 ABSTRACT

摘要

We present the results of corefloods of various gaseous solvents into cores filled with extra-heavy oil,performed as part of an integrated approach to design a solvent injection field test for an unconsolidated sand reservoir containing extra-heavy oils. This paper first describes the design of the initial solvent composition through thermodynamic simulations,leading to a C2-C3 mixture as optimal solvent.Then,we will describe alternative solvent choices,based on the use of CO2 instead of C2;an extreme choice of pure CO2 as solvent will also be evaluated. Then,we will describe the design and the realisation of 3 coreflood experiments performed under reservoir conditions,with previously described solvents.Solvents were injected into 40 cm cores monitored with 1D X-ray.These experiments were matched with numerical simulations,in an attempt to get relative permeabilities.However,these matches were not complete,as no experimental PVT full description of the oil-solvent mixtures were available: this interpretation process still has to be completed. These experiments showed that this family of solvents provides large microscopic recoveries,with adequate sweep efficiencies,and observable solvent effects.The way forward will then be to use the physical parameters derived from the final interpretation of the experiments to confirm the efficiency of these solvents at field scale.