Physical and Numerical Simulation of an Extra-Heavy Crude Oil Downhole Upgrading Process Using Hydrogen Donors Under Cyclic Steam Injection Conditions

摘要

Cesar Ovalles;Jorge Martinis;Alfredo Pérez-Pérez;Edgar Cotte;Luis Castellanos;rnHéctor Rodríguez P.O. Box 76343, Caracas 1070A, Venezuela;Héctor Rodríguez P.O. Box 76343, Caracas 1070A, Venezuela;Héctor Rodríguez P.O. Box 76343, Caracas 1070A, Venezuela;Héctor Rodríguez P.O. Box 76343, Caracas 1070A, Venezuela;Héctor Rodríguez P.O. Box 76343, Caracas 1070A, Venezuela;rnrnAbstractrnPhysical simulation experiments of a Downhole UpgradingrnProcess showed that use of a hydrogen donor additivern(tetralin) in the presence of methane (natural gas) and thernmineral formation under steam injection conditions (280°Crnand residence times greater than 24 h) led to an increase of atrnleast three degree in API gravity of the treated Extra-HeavyrnCrude Oil, three-fold viscosity reduction and, approximately,rn8% decrease in the asphaltene content with respect to thernoriginal crude. In the present work, a continuous bench scalernplant was used at different temperatures (280-315°C) andrnresidence times (24-64 h) for carrying out kinetic studies. Arnreaction model involving four pseudo-components (light,rnmedium, heavy and asphaltene fractions) was used and thernkinetic parameters (pre-exponential factors and activationrnenergies) were determined. Using these data, compositional-thermalrnnumerical simulations were carried out and validatedrnusing the bench scale data. The results showed a good matchrnbetween the calculated and experimental °API gravities of thernupgraded crude oil (average relative error 4%)rnUsing the previous model, the Downhole Upgrading Processrnwas numerically simulated under cyclic steam injectionrnconditions (injection of 2500 bbl/d of 1:1 steam/tetralin withrn75% quality steam) for 20 days, followed by 10 days ofrnsoaking period) in a typical Orinoco Basin reservoir (9°API).rnThe simulation runs showed the production of 12°APIrnupgraded crude oil, accumulated over a 100 day-cycle.rnHowever, a reduction in the percentage of conversion ofrntetralin was observed (0.8%) in comparison with the benchrnscale experiments (3%), which was attributed to gravitationalrnsegregation of the steam coupled with low mixing efficiencyrnof the hydrogen donor with the extra-heavy crude oil atrnreservoir conditions.