Joe Dunn Clegg, Shell Western E&P, Inc.
A review of the many types of gas anchors and their principles should be of interest to those who are concerned with pumping oil wells. The fact that free gas reduces pumping efficiency was discovered early on. An obviously better way to produce most such wells was to flow the gas up the casing annulus and pump only the liquids (oil and water). Some down-hole equipment arrangements were found to be better than others. As a result, many operators began investigating ways to improve pumping. A U.S. patent for a gas anchor was issued in 1881 to Crowley. Many more patents on gas anchors have since been issued; however, not all of them necessarily increase pumping efficiencies. The name "gas anchor" is a misnomer -- it is actually a down-hole gas and liquid separator. There are many types and their use is often misunderstood.