摘要
•Implicit higher-order finite element methods are developed for fractured reservoirs.•Implicit transport updates are ∼ 103 times faster than a previous IMPEC scheme.•Lower-order implicit methods show high numerical dispersion and require fine grids.•Higher-order methods provide high accuracy and a 102−103102−103 speed-up factor.•First-contact-miscible CO2 injection with fingering in compressible oil is modeled.