Influences of fracture orientation on oil recovery by water and polymer flooding processes: An experimental approach

摘要

The major objectives of this study are to experimentally investigate the influences-of fracture orientation on oil recovery by water and polymer flooding processes.Four flood experiments were conducted at simulated reservoir conditions of temperature and pressure.The fifth experiment was carried out using core sample without fracture as.a base run to compare the performance of fractured and unfractured formations under water and/or polymer flooding(s).Viscosity variation of actual crude oil and polymer solutions of different concentrations was measured under different temperatures. The results indicated that water-flooding the unfractured carbonate reservoirs provided higher oil recovery than formations of a single fracture.A carbonate reservoir of a single-horizontal fracture in the direction of oil flow (0 deg inclination angle) recovered the highest oil recovery while a similar formation of a single-vertical fracture perpendicular to oil flow direction (90 deg inclination angle) produced the lowest one by waterflooding.The increase of fracture inclination angle decreases oil recovery by waterflooding. For polymer flooding after complete waterflooding,the results showed that all fractured carbonate formations of different inclination angles produced higher oil recovery than unfractured ones.The highest oil recovery by polymer flooding was produced from formation of a single fractured of 30 deg inclination angle,while the lowest recovery was obtained from formation of 90 deg inclination angle.In addition,the ultimate recovery of combined water and polymer flooding processes in fractured carbonate reservoirs proved that the best recovery was gained from the horizontally fractured formations.