Microscopic Visualization with High Resolution Optical-Fiber Scope at Steam Chamber Interface on Initial Stage of SAGD Process

Abstract Experiments and numerical simulations on initial stages of the steam-assisted gravity drainage (SAGD) process were carried out. Experimental studies used two-dimensional scaled reservoir models to investigate fluids flow characteristics in the steam chamber and production fluids. The rise and growth of the initial steam chamber were observed and visualization of micro-phenomena at inclined interface on the side of the steam chamber with a high-resolution optical-fiber scope was carried out. Very fine water droplets of 0.01 mm order in size were observed at the interface between steam and heavy oil phases. These droplets entered into heavy oil phase and created emulsion together with the heated oil, which flowed down and was produced from the production well. It was successfully demonstrated that these micro phenomena has an influence on chamber expansion rate in horizontal direction and oil production rate. The numerical simulation of the SAGD process was also performed. The thermal simulator, CMG's STARS™ was used to simulate the experimental steam chamber growth at the initial stage. The simulation used the two-components (water and heavy oil) black oil, three-phase (water, heavy oil and steam) and three-dimensional numerical model for the physical model. The results from the history-matched numerical simulation were found to be in good agreement with those of the experiments for oil production and steam chamber shape by using the Intermediate3-Stone1 wettability model represents fluids behavior cumulating the microscopic phenomena at the chamber interface. Furthermore, a new process named Surfactant-SAGD injecting a surfactant before starting steam injection to enhance the communication between two wells and mobility of the production fluids was tested.