Annular-Velocity Enhancement With Gas Lift as a Deliquefication Method

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 130256, ’Annular Velocity Enhancement With Gas Lift as a Deliquification Method for Tight Gas Wells With Long Completion Intervals,’ by S.A. Pohler, SPE, W.D. Holmes, SPE, and S.A. Cox, SPE, Marathon Oil Corporation, originally prepared for the 2010 SPE Unconventional Gas Conference, Pittsburgh, Pennsylvania, 23-25 February. The paper has not been peer reviewed. It is common practice in the industry to complete multiple reservoirs in a single wellbore to establish commercial production rates from tight gas completions. In some cases, these zones are separated vertically by several hundred to more than 1,000 ft. The deliquefication of these completions is one of the most challenging problems facing our industry. Many of the deliquefication methods currently being used are effective over only a portion of the wellbore. Introduction It is common practice to complete tight gas wells with the tubing tail above the bottom perforation. This completion practice allows static liquid to stand across the lower set of perforations. Static liquid standing across the perforations promotes increased near-well liquid saturations through a process of spontaneous imbibition. The imbibition process is a damage mechanism that can be present upon initial completion and can continue throughout the productive life of the well if allowed to form through ineffective liquid-removal/completion practices. There are a number of different methods currently in use for the deliquefication of gas wells. Some of the more common are plunger lift, chemical-foam lift, and conventional pumps (i.e., rod pumps, electrical submersible pumps, and progressing-cavity pumps). Each method has drawbacks when it comes to deliquefying wells with long completion intervals. Effective liquid removal can improve overall well performance significantly. However, an effective system cannot ignore the potential presence of a static liquid column. Current completion technology has been found to have limited effectiveness when long productive intervals are involved. Therefore, a modified continuous-flow gas lift system is proposed that includes a packer and crossover system and that allows for gas lifting the well below the bottom perforation. The details of this completion process and its field applications are discussed in the body of the full-length paper.