Use of Vent Strings in Artificially Lifted Wells

During recent years, multiple completions have become more commonplace. This is to be expected due to the obvious economic advantages derived from producing two or more allowable while having to drill but one hole. Problems encountered in producing multiple completions, as in single completions, are usually minimal, until artificial lift is required. With the installation of lift equipment, production from zones beneath a packer can be adversely affected if the pump intake pressure is below the bubble point of the produced fluid and the gas production is not adequately vented. The use of vent strings in these cases can result in maintaining producing rates at or near normal, and thereby increase income and shorten producing life over what would be anticipated if the well were produced unvented. This paper presents some limited data on producing from beneath a packer with the gas production vented and unvented. Venting through one-inch tubing strings is compared with annular venting. A method, with a trial and error solution, of predicting unvented production is also presented.