Formation of gas bubble-water dispersion system using ultrasonic vibration method and research on its impact on ultimate oil recovery
Author of the article:CHEN Xinglong1,2, WU Jiazhong1,2, HAN Haishui1,2, LIU Li1,2
Author's Workplace：1. PetroChina Research Institute of Petroleum Exploration & Development, Beijing, 100083, China; 2. State Key Laboratory of Enhanced Oil Recovery, Beijing, 100083, China
Key Words：Ultrasonic vibration; Gas bubble-water dispersion system; Gas bubble radius; Micro size; Oil displacement experiment
Abstract：To address the issue of channelling effect and difficulties in displacing remaining oil reserves in the later stage of water flooding, a gas bubble-water dispersion system was developed, in which the gas was dispersed in water to form uniform and stable micro bubbles. According to the principle of ultrasonic vibration, combined with the shear action of microorifice plate, micro gas bubble dispersed in water was produced in the laboratory. Using a stereo-microscope to take measurement from photos taken by high speed camera, the average micro bubble radius is found to be approximately 2.5 μm, which is much smaller than the 50 μm radius bubbles produced through the conventional orifice injection method. In addition, the uniformity, dispersiveness and stability of the bubbles are greatly improved. With bubble diameter and bubble rising velocity as key parameters, the performance evaluation method of dispersed gas bubble in water system is established. The characteristics of micro bubble generated by ultrasonic high frequency vibration method are theoretically evaluated. According to the oil displacement experiment using low permeability core with a length of 100 cm and a diameter of 3.8 cm, micro gas bubble-water dispersion system can continue after the end of water flooding and increase ultimate oil recovery by more than 10%. Therefore, it proves that the gas bubble-water dispersion system can effectively expand the swept volume and improve the ultimate recovery of remaining oil-in-place by means of bubble size change and regulation of seepage resistance.