Extending the Range of Gas Lift to Long Perforations

Abstract

Abstract Problem being addressed: Operators face many challenges when producing deep vertical wells and long horizontal or deviated well bores. Traditional artificial lift methods can prove inefficient or ineffective when applied to this new breed of wells. Challenges: In wells with long perforated intervals, insufficient velocities below the packer can cause liquid loading. Many traditional artificial lift methods are limited in their ability to address liquid loading issues in these types of wells. Solution: If gas can be injected below the packer and deep into the perforated zones, gas lift can be an effective means of deliquification. Advances in gas lift system design now provide several options for effectively recovering liquids from completion intervals below the packer. We will discuss a few of these systems, including Annular Bypass Assembly (ABA), Dip Tube, Enhanced Annular Velocity (EAV), Marathon AVE, and Dead String. Each employs unique techniques that allow for gas injection deep into the perforated zone by passing the lift gas through or around the packer. Using the basic principles of gas lift, the injected gas aerates the liquid in the perforated zone, decreasing the hydrostatic density and flowing gradient and improving inflow from the formation. By also increasing velocity in the production string, these gas lift systems allow operators to more efficiently recover fluids and minimize or prevent liquid loading. Results: Below-packer gas lift systems are being used successfully to economically produce wells in unconventional plays. We will review the design and mechanics of each of the above-mentioned systems, share our experiences working with operators and discuss the selection criteria in choosing a system.