A Way To Eliminate Fluid Gas Pound With The New Two-Stage Charger Valve

Lack of submergence and gas interference are the principal causes of poor pump efficiency; both create fluid pound. Fluid pound contributes greatly to rod parts, bearing and gear failure in pumping units, V-belt failure and prime mover damage. The greatest loss is in production when gas interference is present. Subsurface gas separators of many designs are being used; these separators are essential. The more gas that is separated from the oil and permitted to escape up the casing before it can reach the pump intake, the better. Some of the gas that remains in solution until it reaches the pump intake will break out of solution as it passes through the dip tube and standing valve. Intermittent pumping will greatly reduce equipment damage where fluid pounds are created by lack of submergence. One can intermittently pump a well with gas interference and reduce damage to equipment, but often at a sacrifice in production. Much of the gas breaks out in the formation and enters the casing through the perforations as free gas. Free gas escapes up the casing at about six inches per second in oil, and this gas should not present a pumping problem unless the well is over-pumped or excessive back pressure is held on the casing. Some gas remains in solution until it enters the pump. Some gas remains in solution even through the pump. This gas breaks out when it reaches its bubble point and quite often flows off. This is called "heading up". Gas-locking occurs when the traveling valve remains closed throughout the stroke. The "Charger" valve supports the fluid load above the traveling valve until near the bottom of the downstroke, then charges the upper chamber with fluid. A fluid pound cannot exist unless the fluid load is supported by the traveling valve on the downstroke. A fluid pound on the upstroke cannot exist if the traveling valve supports the entire fluid load. With a "Charger" valve, the seal opens at the beginning of the upstroke because the pump is filled with liquid. The seal closes and supports the fluid load at the beginning of the downstroke. The upper chamber approaches zero psi quickly after the plunger starts its downward movement. The fluid and gases in the lower chamber simply pass through the traveling valve as it moves down. The fluid load is supported by the seal and the buoyant effect is eliminated permitting the rods to fall more freely, thus increasing the weight of the rods on the downstroke. In every test we have to date, the range of load in rods has been reduced because of this increased weight on the downstroke. The peak polished rod loads have remained about the same or have been reduced, except in one test where there was an increase, which will be discussed later.