Theoretical, experimental and simulation analyses of the ball-sealer downhole movement for thermal recovery of heavy oil

Abstract

Plugging blastholes by ball-sealers is an effective method to enhance the thermal recovery of heavy oil, while the downhole movement of ball-sealers is unclear. In this study, four analysis methods including velocity, forces, simulation and experimental analysis were employed to understand the movement of ball-sealers in steam. The results show that the slippage velocity of ball-sealers in steam is positively correlated with the density and diameter of ball-sealers, the quality and injection rate of steam, while negatively correlated with the steam temperature. The vertical drag force increases with the density of ball-sealers. The vertical and horizontal drag force as well as force of removal from the blasthole increases with the diameter of ball-sealers. Four forces are positively correlated with the quality and injection rate of steam. Therefore, the temperature, quality and injection rate of steam play an important role in the effective plugging of ball-sealers. Additionally, the higher the gas velocity and the turbulent viscosity is, the bigger the forces will be generated. The gas velocity could be adjusted to control the plugging position. The success rate of ball-sealers depends on the velocity and viscosity fields. Experimental results show that the success rates are as high as 86.64% and 73.28%.