Experimental study on nitrogen and nitrogen foam-assisted gravity drainage for enhancing oil recovery

Abstract

Abstract Many factors will affect the result of nitrogen-assisted gravity drainage (NAGD). In this work, sandpack and 2-dimensional (2D) visual plate model were employed to investigate the influence factors of NAGD, such as gas cap volume, formation dip angle, and back pressure. Nitrogen foam was also studied to improve the gas channeling and breakthrough. The experimental results indicated that the gas cap volume was the most significant influence factor on the oil recovery. With the increase of the gas cap volume, the oil recovery increased first and then decreased, and finally increased. The NAGD had a better performance in big dip angle of formation. There was a critical value of back pressure to obtain the maximum oil recovery. However, the gas channeling was intensely observed by experiments of both sandpack and 2D visual plate model. Fortunately, nitrogen foam could effectively inhibit the gas channeling and improve the result of NAGD.

Keywords

• Gas cap volume
• Formation dip angle
• Nitrogen-assisted gravity drainage
• Nitrogen foam