Patent ID: 7810570
Filing Date: 2010-10-12
Classification: E21B

Abstract:
1. A method for fracturing subterranean formations penetrated by a wellbore comprising: accessing the formation with a conveyance string having a bore and extending downhole through the wellbore for conveying a tool to the formation; isolating a zone with the tool, the tool having an uphole seal and a downhole seal spaced uphole and downhole of the isolated zone; closing the bore of the conveyance string at a valve at the tool, the valve having a main piston which is biased to close the valve and is pressure-actuated to open the valve, the closing of the bore accumulating a gaseous fracturing fluid along an entirety of the conveyance string or wellbore uphole of the valve, the gaseous fracturing fluid being accumulated to a threshold pressure; opening the bore of the conveyance string at the valve at the threshold pressure, the opening of the bore further comprising closing the valve comprising