Selected well completion for improving vertical conformance of steam

Abstract

The method combines the driving of oil by steam from an injection well to a production well with the overriding tendencies of the steam to give both good temperature conformance and good vertical sweep by completing the injection and production wells in limited intervals in the oil-containing formation. The injection well is completed in the bottom 20-30 percent of the vertical thickness of the oil-containing formation and the production well is completed in the bottom 40 percent of the vertical thickness of the oil-containing formation. Once the wells are completed over the limited intervals, steam is injected into the oil-containing formation at a rapid rate and fluids including oil are recovered from the formation via the production well. Injection of steam is continued until the fluid being recovered contains an unfavorable amount of steam or water. If the oil-containing formation overlies a water-saturated formation, optimum vertical conformance is obtained with the completion interval of the injection well in the bottom 20-30 percent of the vertical thickness of the oil-containing formation and the production well completed over 30-40 percent of the vertical thickness of the oil-containing formation beginning at a point above the water-saturated formation a distance of about 10 percent of the vertical thickness of the oil-containing formation.