Patent ID: 9181789
Filing Date: 2015-11-10
Classification: C09K,E21B

Abstract:
1. A method of operating a hydraulic formation fracturing system that uses a fracturing fluid comprising natural gas, the method comprising: (a) providing a formation fracturing system including a natural gas supply apparatus comprising a natural gas source, a pump assembly for pressurizing natural gas from the natural gas source, and fluid supply conduits for transporting the natural gas from the natural gas source to the pump assembly and to a wellhead of a well that is in communication with an underground formation to be fractured; (b) forming a fracturing fluid by providing natural gas from the natural gas source and pressurizing the natural gas to a fracturing pressure of the formation using the pump assembly; (c) injecting the fracturing fluid through the wellhead and into the formation until the formation is fractured; (d) injecting an inert fluid through at least part of the formation fracturing system before or after injecting the fracturing fluid through the wellhead and until any residual natural gas and oxygen, or air in the at least part of the formation fracturing system is purged to a non-flammable state; and (e) after injecting the inert fluid through the at least part of the formation fracturing system, venting at least some of the injected inert fluid.