Methods for identifying compounds useful for producing heavy oils from underground reservoirs

Abstract

Described herein are methods for identifying compounds useful for producing heavy oil from an underground reservoir. The methods facilitate the development of chemicals with improved physicochemical features. The methods generally involve first identifying a physicochemical property of a compound that needs to be improved in order to increase the efficiency of heavy oil removal from underground reservoirs. Next, the physicochemical property is calculated by molecular modeling using semi-empirical or ab-initio calculations. By modifying the molecular model of the compound, the targeted physicochemical property can be optimized. After a suitable compound has been identified, the compound can be synthesized and evaluated.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Application No. 60 / 985,316, filed Nov. 5, 2007, which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The number of steam assisted gravity drainage (SAGD) wells drilled in countries such as Canada is expected to increase in view of current demands for oil and fuels. In view of this, improving the production rate and / or increasing the total recovery from SAGD wells, and by Huff and Puff and cyclic steam stimulation (CSS) of wells, through the use of chemicals is highly desirable. Chemistry that can enhance the sweeping efficiency of the injected steam or hot water in the heavy oil reservoir is particularly desirable. When this approach is used globally in a reservoir, the production rate and total recovery is enhanced. Alternatively, when it is used locally, the use of chemicals can increase the local sweeping efficien...

AI Technical Summary

Benefits of technology

[0008]Described herein are methods for identifying compounds useful for producing heavy oil from an underground reservoir. The methods facilitate the development of chemicals with improved physicochemical properties. The method generally involves first identifying a physicochemical property of a compound that needs to be improved in order to increase the efficiency of heavy oil removal from underground reservoirs. Next, the physicochemical property is calculated by molecular modeling using semi-empirical or ab-initio calculations. By modifying the molecular model of the compound, the targeted physicochemical property can be optimized. After a suitable compound has been identified, the compound can be synthesized and evaluated.

Problems solved by technology

In practice, SAGD and CSS is unlikely to reach 100 percent recovery of swept zones, which would require significant time and energy consumption to recover all the contained oil.

The hindered recovery of heavy oils can be attributed to both the unfavorable wetting properties of the solid matrix and the high interfacial tension between the organic and aqueous phases.

The oil is trapped in narrow capillaries, where the gravitational and hydrodynamic driving forces cannot overcome the resisting capillary forces.

However, a fraction of the oil phase remains trapped in the capillaries because of the oil-wet condition of the reservoir.

The oil can also be trapped when there are narrow passes in the capillaries, even in case of a water-wet reservoir.

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