Method for recovering viscous petroleum

Abstract

Abstract Steam flooding is frequently unsuccessful in viscous petroleum-containing formations such as tar sand deposits due to loss of steam transmissibility caused by the steam condensing deep in the formation and also caused by heated viscous petroleum forming an oil bank and losing heat and becoming more viscous as it moves through the formation, eventually becoming essentially immobile and blocking further flow through the formation. By injecting a non-condensible, non-oxidizing gas ahead of and/or in combination with steam, this tendency to block or plug the flow channels is reduced or eliminated. Steam and non-condensible, non-oxidizing gas are injected into the formation at a pressure in pounds per square inch not exceeding numerically the overburden thickness in feet in order to avoid fracturing the overburden. Steam and non-condensible, non-oxidizing gas may be mixed prior to injection or injected sequentially or simultaneously to mix in the formation. If steam and non-condensable, non-oxidizing gas are injected separately and simultaneously or sequentially, it is preferred that the gas be injected at a point below where the steam is injected. Steam and gas should be injected so substantially all of the formation to be contacted by injected fluid is contacted by a mixture of steam and the non-condensible, non-oxidizing gas. Suitable non-condensible, non-oxidizing gases include nitrogen, carbon dioxide, flue gas, exhaust gas, natural gas, liquefied petroleum gas, methane, ethane, propane, butane, pentane, hydrogen, and mixtures thereof. Saturated or supersaturated steam may be used.

Inventors

• 👤 Joseph C. Allen

Bibliographic Details