This research covers simulation of Cyclic Steam Stimulation (CSS) Thermal Enhanced Oil Recovery (TEOR) and potential benefits for use of produced water in agriculture and food security, using a case study of oil fields in South Sudan. Oil production in many oil fields in South Sudan is declining, has high water cut, and low recovery factor. It is costly to manage the produced water. At the same time, agriculture in South Sudan is almost entirely rainfed, and this affects food security. Produced water can be managed by using it for TEOR and agriculture to solve water management issues, enhance oil production, reduces competition over water resources, and improve food security. Field A is a deep reservoir in South Sudan with oil gravity between 25 and 31 API. There are limited and mixed results from applications of TEOR methods in deep reservoirs. As such history matching and sensitivity analysis, and CSSS TEOR simulations were performed to examine most uncertain reservoir properties and the compatibility of Field A properties with CSS TEOR method. The results of simulation show that aquifer volume (AQV) and productivity index (PI) are the most uncertain property that affect reservoir pressure; cumulative oil, gas, and water production; water cut; and gas oil ratio. CSS TEOR simulation was not successfully due to the high API gravity suggesting that Field A is not a good candidate for CSS TEOR.
The produced water is sufficient to irrigate large areas of farms and watering thousands of livestock. However, analysis results from untreated water; water treated by demulsifer-defoamer and bioremediation shows high total dissolved solids (TDS) and sodium absorption ratio (SAR) values. Therefore, reverse osmosis (RO) membrane technology was applied to treat the produced water. RO rejected more than 90% of elements in the produced water with exception of elements B, Cu, Pb, and Ca. Consequently, water from RO does not meet food and agriculture organization (FAO) standards for all uses in agriculture. ANOVA showed that there was no significant difference in TDS reductions between the different applied treatment technologies. Therefore, caution is needed when using statistical analysis to verify operationalization of RO technology which rejected more than 90% of the elements in the produced water.