Patent ID: 8448708
Filing Date: 2013-05-28
Classification: E21B

Abstract:
1. A method for stimulating flow of petroleum fluids from a subsurface formation into a wellbore drilled into and exposed to the formation, said method comprising the steps of: (a) providing a string of return tubing having an upper end and a lower end; (b) providing a string of supply tubing having a cylindrical sidewall, with a portion of said supply tubing defining an orificed section having a plurality of orifices extending through said cylindrical sidewall; (c) disposing the return tubing string within the wellbore so as to form a well annulus between the return tubing and the wellbore; (d) disposing the supply tubing string within the return tubing string so as to position the orificed section of the return tubing at a selected location within the wellbore, and so as to form a tubing annulus between the supply tubing and the return tubing; (e) ensuring that an aqueous fluid is present in a region of the well annulus proximal to the first orificed section of the supply tubing; (f) initiating a freezing cycle by introducing a flow of liquid refrigerant into the supply tubing, such that the refrigerant passes through the orifices in the orificed section thereof and resultantly vaporizes and flows into the tubing annulus, and continuing the flow of refrigerant so as to freeze the aqueous fluid in said region of the well annulus proximal to the orificed section, and so as to freeze an adjacent first region of the subsurface formation; and (g) initiating a thaw cycle by discontinuing the flow of refrigerant and allowing said first region of the subsurface formation to thaw.