Abstract

Among several oil recovery techniques, hot waterflooding through thermal displacement processes could potentially increase oil recovery by decreasing oil viscosity, thus decreasing the mobility ratio at a relatively low cost compared to other thermal methods such as SAGD or in-situ combustion. These methods can also be applied in specific in-situ conditions such as formation sensitivity to fresh water. This paper examines the performance and feasibility of hot waterflooding and compares the performance with a conventional recovery scheme of a heavy oil reservoir with an oil gravity of 10.6 °API and viscosity of 13,400 mPa‧s (at 22 °C) from the Lloydminster area (Canada); the approach includes numerical thermal simulation and economical analysis of each process. First, the performance of a hot waterflood on a generic model consisting of a 5-spot injection pattern was investigated. Then four field designs were recognized from several previously analyzed patterns. The effect of well spacing, horizontal well configuration, injection parameters, as well as the impact of incremental temperature adjustment of waterflood on heavy oil recovery were studied. More than 220 models were built on the final patterns and the most economic configuration was found to have four horizontal producers and four horizontal injectors with a well spacing of 67 m. This arrangement resulted in a recovery factor of more than 30 % of the oil originally in place (OOIP). The most economic injection rate was determined to be 400 m3/day of water at optimum injection temperature of 80 °C. It was also observed that by increasing the temperature of the injected water, the oil viscosity could be reduced to less than 100 mPa‧s. This improved the oil recovery and production rate, delayed injection breakthrough, and reduced water cut. From the results, the highest injection temperature of 100 °C could be recommended; however, the incremental oil versus the amount of heat and facilities required would not be justifiable from an economic point of view.

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