Producing heavy oil from tar sands
First Claim
1. In the recovery of heavy oil from an underground tar sand reservoir by injecting steam into at least one injection well penetrating said reservoir so that permeability of the reservoir is obtained and the tar sand contacted by the steam is heated and mobilized, heavy oil is produced from at least one producing well penetrating the reservoir, the improvement of:
- a. injecting a surface-active agent dissolved or dispersed in a suitable carrier into at least one injection well, therebyb. generating a condensible foam,c. penetrating the more permeable portions of said reservoir with said foam, therebyd. diverting steam into less permeable portions of said reservoir, ande. injecting an amount of steam into said underground tar sand reservoir to, at least, elevate the pressure in the reservoir contained by said condensible foam sufficiently to sustain the porosity of the tar sand reservoir.
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Accused Products
Abstract
A method is provided for recovering heavy oil from an underground tar sand reservoir by injecting steam into an injection well penetrating the reservoir sufficiently to fracture the tar sand and provide passage for the steam through the tar sand to a production well piercing the tar sand reservoir. Steam is provided at sufficient heat to mobilize heavy oil from the permeated tar sand and a pressure sufficient to maintain competency of the formation to permit continued flow from the injection well to the production well. Injection of surfactant into the tar sand reservoir is used to produce a condensible foam which aids in maintaining back pressure on the injected steam within the tar sand reservoir to maintain the competency of the formation and to cause further permeation of the formation by the steam. Foam can be produced of strength sufficient to permit pressure to be applied in the tar sand reservoir capable of further fracturing the reservoir.
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Citations
6 Claims
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1. In the recovery of heavy oil from an underground tar sand reservoir by injecting steam into at least one injection well penetrating said reservoir so that permeability of the reservoir is obtained and the tar sand contacted by the steam is heated and mobilized, heavy oil is produced from at least one producing well penetrating the reservoir, the improvement of:
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a. injecting a surface-active agent dissolved or dispersed in a suitable carrier into at least one injection well, thereby b. generating a condensible foam, c. penetrating the more permeable portions of said reservoir with said foam, thereby d. diverting steam into less permeable portions of said reservoir, and e. injecting an amount of steam into said underground tar sand reservoir to, at least, elevate the pressure in the reservoir contained by said condensible foam sufficiently to sustain the porosity of the tar sand reservoir. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification