Effect of Fracture Inclination on Oil Recovery by Steam Heating in Fractured Reservoirs

The major objectives of this study are investigating the influences of fracture inclination on oil recovery by steam injection processes. The strongest recovery mechanism in steam injection is reduction of viscosity ratio. In this article, steam heating of a naturally fractured reservoir is modeled in terms of a block with a single fracture surrounded by steam. An analytical approach is used, which considers the transient temperature distribution within a single block. A heat integral method is used to obtain the unsteady-state temperature profile. The temperature distribution is used to calculate drainage rate under gravity flow. The solutions obtained are used to determine the effect of fracture inclination and some other parameters on the oil rate in steam injection. The results indicated that a single horizontal fracture in the direction of oil flow (zero inclination angle) recovered the highest oil, while a similar formation with a single vertical fracture perpendicular to oil flow direction (90 degrees inclination angle) produced the lowest oil rate in steam heating. The increases of fracture inclination angle decreases oil recovery during steam heating. In addition, the recovery of oil for matrix with a single horizontal fracture is less dependent on average steam temperature, and this dependency becomes more as fracture inclination approaches to 90 degrees (matrix with vertical fracture).