Oil wells are holes drilled in the earth to bring petroleum hydrocarbons to the surface. Often some natural gas is released with the oil as associated petroleum gas. A well designed to produce only natural gas may be referred to as a gas well. Wells are created by drilling down into oil or gas reser

In the case of oil wells, pumping is a routine operation that involves injecting fluids into the well. Pumping can be done through a kill wing valve fitted to the Christmas tree, or, if an intervening device is present, through a T-piece (a small section of the riser with connections on the side) in