Impact of Fracture Permeability on Oil Recovery in Moderately Water-Wet Fractured Chalk Reservoirs

摘要

The impact of fracture permeability on oil recovery frommoderately-water-wet chalk has been determined. NuclearTracer Imaging was used to measure local fluid movement andto identify locations of trapped oil resulting fromwaterflooding a sleeved, fractured chalk block. Increasing theconfinement pressure between experiments decreased thepermeability of an interconnected fracture network for eachsequential waterflood. The experiments showed that thedominant oil recovery mechanism was spontaneousimbibition, however, viscous oil recovery added significantlyto the total oil production when the permeability ratio betweenthe fractured system and the matrix was less than 20. Theamount of oil viscously recovered increased as the fracturepermeability decreased.