Increasing permeability of subsurface formations

Claim 1

IN A METHOD FOR INCREASING THE PERMEABILITY OF A SUBSURFACE EARTH FORMATION HAVIN G AFRACTURE EXTENDING FROM A WELL BORE INTO SAID SUBSURFACE FORMATION THE IMPROVEMENT COMPRISING INJECTING INTO THE WELL BORE AND THENCE INTO SAID FRACTUREA A CARRIER FLUID CONTAINING SOLID PARTICLES OF A GENERALLY SPHERICAL PROPPING AGENT HAVING AN AVERAGE PARTICLE DIAMETER BETWEEN ABOUT 0.03 AND 0.25 INCH, SAID CARRIER FLUID BEING CAPABLE OF SUSPENDING SAID PROPPING AGENT SO THAT SAID PROPPING AGENT WILL SETTLE AT A RATE OF LESS THAN 0.1 FOOT PER MINUTE THROUGH SAID CARRIER FLUID AND THE CONCENTRATION OF SAID PROPPING AGENT IN SAID CARRIER FLUID BEING EQUAL TO C=231(MN/D) WHERE C IS THE CONCENTRATIN OF SAID PROPPING AGENT IN POUNDS PER GALLON OF SUSPENSION, M IS THE AVERAG MASS PER PARTICLE OF SAID PROPPING AGENT IN POUNDS, D IS THE AVERAGE PARTICLE DIAMETER OF SAID PROPPING AGENT IN INCHES AND N IS A SELECTED NUMBER OF PARTICLES OF SAID PROPPING AGENT PER SQUARE INCH OF FRACTURE FACE BETWEEN N=1/D**1/2 AND N=P/S WHERE P IS THE PRESSURE OF THE FRACTURE WALLS IN POUNDS PER SQUARE INCH AND S IS THE AVERAGE LOAD IN POUNDS AT WHICH INDIVIDUAL PARTICLES OF SAID PROPPING AGENT WILL CRUSH INTO SMALL FRAGMENTS ANDDISCONTINUING INJECTING OF SAID CARRIER FLUID CONTAINING SAID PROPPING AGENT BEFORE THE LAST INCREMENT OF SAID CARRIER FLUID AND SAID PROPPING AGENT REACHES A POINT IN THE WELL BORE OPPOSITE THE TOP OF SAID FRACTURE.