Influence of Temperature on Gel Treatment under Various Reservoir Wettability Conditions

Abstract

Heterogeneous reservoirs which especially characterize high permeability contrast bring about excessive water production. To avoid disproportionate water production, permeability reduction techniques are proposed and gel treatment is well-known as effective one of them. Previous studies have revealed the gelation of various gel types is sensitive to temperatures. Also, wettability of reservoir determines different performance. To date, most of former researches are carried out only concerning relationships between wettability and gel treatment or between temperature and gel treatment, mainly by experiments. To overcome these limitations, the assessment of non-isothermal gel treatment requires a model as a function of temperature under consideration of wettability of reservoir. Using a reservoir simulator including the model for wettability, extensive numerical studies have been performed to investigate the effect of temperature on the water-oil ratio and cumulative oil recovery. Analyzed target is the layered reservoir which has severe permeability contrast in vertical direction and low vertical communication with an injector under gel treatment followed by water flood. Results from a number of scenarios of different temperatures of reservoir and injection fluid clearly prove the temperature dependency of performance. The model can be used as quantitative tool to evaluate the comparative studies of gel treatment with respect to temperature dependency under different wettability of reservoir. The significant improvement is observed in both water-wet and oil-wet reservoirs as temperature elevates. However, improvement of performance of gel treatment according to temperature in oil-wet reservoir shows different results comparing with that in water-wet reservoir. As reservoir temperature increases, water-oil ratio in water-wet reservoir decreases more rapidly than that in oil-wet reservoir. Increases in oil recovery of oil-wet reservoirs are obtained while slight decreases in water-wet reservoirs. In terms of injection fluid temperature, the higher injection temperature, the more improvement in water-oil ratio is noticed for water-wet reservoir than oil-wet reservoir.