Method for fracturing a subsurface formation

Claim 1

A METHOD FOR FRACTURING A SUBSURFACE FORMATION PENETRATED BY A WELL AND PROPPING THE FRACTURE OPEN WHICH COMPRISES INJECTING A FRACTURING LIQUID HAVING PARTICLES OF A GRANULAR PROPPING MATERIAL SUSPENDED THEREIN INTO THE UPPER PART OF THE BOREHOLE OF THE WELL, PASSING A PORTION OF THE FRACTURING LIQUID THROUGH A SCREEN IN THE UPPER PART OF THE BOREHOLE AND DISCHARGING SAID PORTION FROM THE WELL WHEREBY A FRACTURING MIXTURE COMPRISING THE FRACTURING LIQUID HAVING A HIGH CONCENTRATION OF GRANULAR PROPPING MATERIAL SUSPENDED THEREIN REMAINS WITHIN THE WELL, AND CONTINUING THE INJECTION OF THE FRACTURING LIQUID WITH THE GRANULAR PROPPING MATERIAL SUSPENDED THEREIN INTO THE WELL AND THE WITHDRAWAL OF A PORTION OF THE FRACTURING LIQUID THROUGH A SCREEN TO DISPLACE FRACTURING MIXTURE HAVING A HIGH CONCENTRATION OF GRANULAR PROPPING MATERIAL SUSPENDED THEREIN DOWNWARDLY THROUGH THE BOREHOLE OF THE WELL TO THE FORMATION TO BE FRACTURED WHILE APPLYING A PRESSURE TO THE FRACTURING MIXTURE ADEQUATE TO FRACTURE THE FORMATION AND DISPLACE THE FRACTURING MIXTURE INTO THE FRACTURE WHEREBY THE GRANULAR PROPPING MATERIAL PROPS THE FRACTURE OPEN.