Experimental Research And Theoretical Analysis Of Relative Permeability Under Thermal Recovery Conditions

It is important to use relative permeability and residual saturation to discribe percolation characteristics of fluids in oil reservoir. There have been many studies, both domestic and abroad, investigating whether temperature will have effects on relative permeability and residual saturation or not. Some of these studies have shown that temperature has little or no effect on relative permeability and residual saturation, while others have shown there to exist some influence.According to differential change of water saturation and irreducible water saturation as temperature changes, a mathematical model is used to discribe the change of temperature-related relative permeability in oil-water system and the formula of relative permeability is theoretically derived in heat treatment process,and oil production is predicted on site with the theory. The rezults have shown that the change of temperature-related relative permeability contributes to the improvements of calculated production and drive efficiency when viscosity is unrelated to temperature, which proves that temperature indeed has effects on relative permeability. The theory equations which is proposed in the paper has enriched and developed analytical method of temperature-related relative permeability.Using oil samples from Qi 40, Du 32 and area 6, the experiments are carried out respectively under 60℃,120℃,200℃water flooding and 200℃steam flooding.By analyzing the parameters, the experimental rezults show the following:1.The water flooding efficiency was related mainly to the rock formation and the interaction between the rock and fluids without having any regard to oil viscosity;2.The rise in temperature causes a noticeable change of irreducible water saturation and residual oil saturation, especially in the process of steam flooding;3.Steam flooding proved more efficient than water flooding in enhancing oil recovery, which is related to its special oil displacement mechanism;The rezult of lab experiments has shown that temperature has many effects on relative permeability and residual saturation, which is consistent with theoretical conclusion of mathematical analysis.