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Controlling and assessing pressure conditions during treatment of tar sands formations

  • US 9,181,780 B2
  • Filed: 04/18/2008
  • Issued: 11/10/2015
  • Est. Priority Date: 04/20/2007
  • Status: Expired due to Fees
First Claim
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1. A method for treating a tar sands formation, comprising:

  • providing heat to at least part of a hydrocarbon layer in the tar sands formation from a plurality of heaters located in the formation;

    allowing the heat to transfer from the heaters to at least a portion of the formation;

    allowing an average temperature of the portion of the formation to increase to a selected average temperature between about 280°

    C. and about 300°

    C. while maintaining a pressure in the portion of the formation below a fracture pressure of the formation overburden;

    assessing the average temperature in the portion by assessing at least one property of gases produced while maintaining the pressure below the fracture pressure;

    reducing the pressure in the portion of the formation to a lower pressure while the portion of the formation is at the selected average temperature;

    increasing the average temperature of the portion of the formation to a temperature of at most about 350°

    C. after reducing the pressure; and

    producing, after the pressure is reduced to the lower pressure, at least some mobilized, visbroken, or pyrolyzed fluids from the portion of the formation at the lower pressure.

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