OVERVIEW

The term aerated fluids describes the broad category of drilling fluids that are basically incompressible fluids injected with compressed air or other gases. Aerated drilling fluids have been used to drill both shallow and deep boreholes since the advent of air and gas drilling technology in the mid-1930s. The first engineering discussion of an aerated drilling mud project was given in 1953 [1]. Aerated drilling fluids were initially used to drill through rock formations that had fracture and/or pore systems that could drain the incompressible drilling fluids (e.g., fresh water, water- and oil-based drilling muds, formation water, and formation crude oil) from the annulus. These borehole drilling fluid theft rock formations are called lost circulation sections. The injection of air into drilling muds has been considered an important technological tool in countering the detrimental effects of lost circulation sections. The injection of air into drilling mud creates bubbles in the mud and, because of the surface tension properties of the bubbles relative to the properties of rock and drilling mud, the bubbles tend to fill in the fracture or pore openings in the borehole wall as the aerated mud attempts to flow to the thief fractures and pores [2]. This bubble blockage restricts the flow of the drilling mud into these lost circulation sections and thereby allows the drilling operations to progress safely. Aerated fluids have been used to avoid lost circulation in shallow water well drilling, geotechnical drilling, mining drilling, and in deep oil and natural gas recovery...