Simulation of Fluid Flow Through Rough Fractures

摘要

Flow through a fracture is usually assumed to take placernbetween two smooth parallel plates. However, it is widelyrnaccepted that the fracture has tortuous paths and roughnessrnand hence the flow behaviour in these paths compared to thatrnin parallel plates is different. Although previous studies havernshown that the fracture aperture follows lognormalrndistribution, studies have not been conducted to determine therndistribution of fracture aperture with changes in stressrnconditions. In this paper, we present fracture aperturernmeasurements under different stress conditions using an XRayrnCT scanner. We developed a calibration curve to obtain arncorrelation between CT numbers and fracture aperture sincernthere is no direct calculation of aperture from CT scanner data.rnAperture distribution patterns from about six thousandrnaperture measurements were obtained for each stress conditionrnevaluated. The results of this study show that the aperturesrnfollow lognormal distribution even at elevated stressrnconditions. We then performed waterflood experiments tornvalidate the use of distributed apertures in simulators. Arnsensitivity analysis was also performed to analyze the effect ofrninjection rates and fracture roughness on oil recovery.