Gas-Assisted Gravity Drainage (GAGD) Process for Improved Oil Recovery

摘要

Water Alternating Gas injection (WAG) or Simultaneous Water and Gas Injection (SWAG) floods have been proposed as very good solution to overcome gravity segregation and better EOR performance in compare to conventional continuous gas injection (CGI). However WAG-Based processes cause some problems associated with increased water saturation including diminished gas injectivity. As an effective alternative for WAG, Gas Assisted Gravity Drainage (GAGD) for conventional reservoirs has been developed (US Patent 2006/0289157) that takes advantage of the natural segregation of gas from liquid hydrocarbon during injection. The GAGD process consists of placing a horizontal producer near the bottom of oil column and injecting gas through existing vertical wells. As the injected gas rises to form a gas zone, oil and water drain down to the horizontal producer. Application of GAGD for IOR in naturally fractured reservoir is discussed here based on some facts and figures.