THE DEPENDENCE OF HOT WATER FLOODING EFFICIENCY ON THE FILTRATION-CAPACITIVE PROPERTIES FOR DOUBLE PERMEABILITY RESERVOIR OF HIGH-VISCOSITY OIL DEPOSITS

Abstract

The study of non-isothermal filtration processes under the conditions of application of thermal effects (hot water injection) in double-permeability reservoirs saturated with high-viscosity oil showed: 1. Thermal impact has a positive technological effect (if we are talking about the final values of oil recovery factor (ORF)), the manifestation of which is delayed in time from the start of the use of hot water flooding (HWF) (from one to ten years) and is accompanied by the selection of a huge amount of produced water (from two to four void spaces). 2. The use of thermal effects in double permeability reservoirs has a number of features. The increase in the final oil recovery factor while HWF relative to the base case occurs mainly due to an increase in the development period with a lower water cut growth rate. However, the water cut value for a long time is close to the limit (98 %). Thus, the HWF effect is mainly manifested when the water content of the products is high. 3. For isothermal filtration variants the dependence of the final ORF on the fracture permeability (with pore blocks constant permeability) has the character of a decreasing curve. Thermal effect reverses this trend, i.e. the final ORF increases with growing permeability of the fracture system and, therefore, with increasing inhomogeneity of the reservoir permeability field. 4. A study of starting watering effect on the final ORF at different values of the of the fracture system permeability showed the existence of two areas of fracture permeability with different trends in the dependence of ORF on the initial water content. While the fracture permeability below 40 μm2, an increase of the initial water-cut value results in a decrease in the final ORF. In the range of fracture permeability values more than 40 μm2, an increase in the initial water-cut increases the final oil recovery factor, while the dependence is not monotonous; starting with water-cut value of 90 %, a decrease in recovery efficiency is observed.