the process of raising or lifting fluid from a well by injecting gas down the well through tubing or through the tubing-casing annulus. Injected gas aerates the fluid to make it exert less pressure than the formation does; consequently, the higher formation pressure forces the fluid out of the wellbore. Gas may be injected continuously or intermittently, depending on the producing characteristics of the well and the arrangement of the gas-lift equipment.

Related Terms

• Injection Gas

1. a high-pressure gas injected into a formation to maintain or restore reservoir pressure. 2. gas injected in gas lift operations. See gas injection....

• Gas Lift Valve

a device installed on a gas lift mandrel, which in turn is put on the tubing string of a gas lift well. Tubing and casing pressures cause the valve to open and close, thus allowing gas to be injected into the fluid in the tubing to cause the fluid to rise to the surface....

• Casing Seal Test

a procedure whereby the formation immediately below the casing shoe is subjected to a pressure equal to the pressure expected to be exerted later by a higher drilling glut density or by the sum of a higher drilling fluid density and back-pressure created by a kick....

• Circulation Loss

The loss of drilling fluid to a formation, usually caused when the hydrostatic head pressure of the column of drilling fluid exceeds the formation pressure. This loss of fluid may be loosely classified as seepage losses, partial losses or catastrophic losses, each of which is handled differently depending on the risk to the rig and personnel and...

• Bullheading

1. Forcing gas back into a formation by pumping into the annulus from the surface. 2. Any pumping procedure in which fluid is pumped into the well against pressure. 3. To forcibly pump fluids into a formation, usually formation fluids that have entered the wellbore during a well control event. Though bullheading is intrinsically risky, it is...