Producing heavy oil from tar sands

• US 4,068,717 A
• Filed: 01/05/1976
• Issued: 01/17/1978
• Est. Priority Date: 01/05/1976
• Status: Expired due to Term

• Current Assignee: Phillips Petroleum Company (ConocoPhillips)
• Original Assignee: Phillips Petroleum Company (ConocoPhillips)
• Inventors: Needham, Riley B.
• Primary Examiner(s): Novosad, Stephen J.
• Application Number:
  US05/646,468
• Time in Patent Office: 743 Days
• Field of Search: 166/272, 166/261, 166/271, 166/263, 166/273, 166/274
• US Class Current: 166/272.5
• CPC Class Codes: C09K 8/592 Compositions used in combination with generated heat, e.g. by steam injection
• CPC Class Codes: E21B 43/18 Repressuring or vacuum methods
• CPC Class Codes: E21B 43/2405 in association with fracturing or crevice forming processes E21B43/247 takes precedence

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.

Claims

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, 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.

2. A method of claim 1 wherein foam is continuously generated in said reservoir.

3. A method of claim 1 wherein foam is intermittently generated within said reservoir.

4. A method of claim 1 wherein said production and injection wells are periodically reversed in function so that flow into and out of said reservoir is periodically reversed.

5. A method of claim 1 wherein said active agent is dissolved or dispersed in a carrier liquid chosen from among alcohols, oils, water and mixtures thereof.

6. A method of claim 1 wherein sufficient steam is injected into said underground tar sand reservoir to raise the pressure in the portion of the reservoir contained by said condensible foam to cause fracture of said tar sand reservoir.