Current Research and Challenges Pertaining to CO2 Flooding and Sequestration see “Gas-Assisted Gravity Drainage” on page 2.
Horizontal Injection and Production Wells for EOR or Waterflooding “Our results show that a very favorable configuration occurs when two opposed horizontal wells are drilled from injection and production wells so that the opposed laterals are parallel in the patterns, and extended until the horizontal parallel in the patterns, and extended until the horizontal segments almost meet midway between the like wells. Compared to five-spot patterns with vertical wells, opposed horizontal wells can increase injectivity (injection rate per applied pressure drop) by as much as a factor of ten, depending on well spacing and formation thickness. Areal sweep efficiency can be increased by 25% to 40%. The horizontal-well advantages are greatest for thin formations with wide spacing, and decline significantly for thick formations and/or close spacing…Because of the better sweep efficiencies, faster flooding rates, and/or lower injection pressures that are possible with horizontal wells, all EOR methods should benefit by their use…”
A Review of CO2-Enhanced Oil Recovery with a Simulated Sensitivity Analysis