Water And Wag Pattern Floods Are Passé
This presentation will describe a new secondary oil recovery method that could potentially make the world’s producible petroleum reserves last decades longer. It is expected to make water and wag pattern floods passé. Its novel element is a unique completion configuration for simultaneous water and gas injection in a pattern flood.
Such injection can provide over 3-fold greater vertical gas sweep than does wag, or alternate injection of gas and water. In reservoirs that have already been previously wag-flooded using vertical wells, simultaneous injection into the existing wells will allow much additional recovery. For example, in prudhoe bay 5 million barrels more oil could be obtained from each 80-acre pattern.
This process can be applied at any time in the life of the reservoir, even after depletion. When combined with the use of horizontal wells, it is effective even in thin reservoirs. The gas does not have to be miscible with the oil to be effective, although recovery is higher if it is miscible. It can be methane, flue gas, or even nitrogen. In fact, the cost or lack of availability of miscible gas may dictate the use of immiscible fluids.