Production from a reservoir which is thin and exhibits high vertical permeability, or contains vertical fractures, or has gas and water conning problems may be improved by using horizontal wells. The implementation of horizontal wells can improve injectivity and oil recovery. The productivity (or injectivity) index of a horizontal well can be greater than that of a vertical well by a factor of approximately 5 to 10. This study was conducted to determine whether horizontal wells could significantly improve predicted oil recovery for a CO{sub 2} miscible flood. A representative 240-acre (1-km{sup 2}) pattern of a west Texas field unit was selected for the simulation study. Predictions of the amount of oil recovered using various horizontal well geometries were compared to the recovery corresponding to vertical injectors and producers. 12 refs., 8 figs., 11 tabs.