Patent ID: 9181780
Filing Date: 2015-11-10
Classification: C09K,C10G,E21B,Y10T

Abstract:
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.