Fracturing method and propping agent

Claim 1

A PROPPING AGENT FOR HOLDING OPEN FRACTURES IN SUBSURFACE FORMATIONS, EACH PARTICLE OF PROPPING AGENT COMPRISING AN INERT CORE HAVING A ROUNDNESS AND SPHERICITY LESS THAN ABOUT 0.7 AND A STRENGTH ADEQUATE TO WITHSTAND THE OVERBURDEN PRESSURE WITHOUT SUBSTANTIAL CRUSHING, A COATING OF SPACING MATERIAL ON THE CORE HAVING A THICKNESS OF FROM ABOUT 0.1 TO ABOUT 1.0 TIMES THE DIAMETER OF THE INERT CORE, SAID COATING BEING READILY SOLUBLE IN FORMATION FLUIDS, AND SAID COATED PROPPING AGENT HAVING A ROUNDNESS AND SPHERICITY HIGHER THAN ABOUT 0.8.

Claim 3

A METHOD OF TREATING AN UNDERGROUND FORMATION PENETRATED BY A WELL TO INCREASE THE FLUID FLOW CAPACITY OF SAID FORMATION INTO THE WELL COMPRISING CREATING A FRACTURE EXTENDING FROM THE WELL INTO THE FORMATION, DISPLACING INTO THE FRACTURE A PROPPING AGENT SUSPENDED IN A LIQUID TO DEPOSIT A MONOLAYER OF PROPPING AGENT IN THE FRACTURE, SAID PROPPING AGENT HAVING AN INERT CORE HAVING A STRENGTH ADEQUATE TO WITHSTAND THE OVERBURDEN PRESSURE ON THE FORMATION WITHOUT SUBSTANTIAL CRUSHING, SAID CORE BEING SURROUNDED BY A COATING OF READILY REMOVABLE SPACING MATERIAL RESISTANT TO THE LIQUID IN WHICH THE PROPPING AGENT IS SUSPENDED, SAID COATING HAVING AN THICKNESS WITHIN THE RANGE OF FROM ABOUT .01 TO ABOUT 1.0 TIMES THE DIAMETER OF THE CORE, RELEASING PRESSURE ON THE LIQUID IN THE WELL WHEREBY THE FACES OF THE FORMATION FRACTURE CLOSE TO HOLD THE PROPPING AGENT IN PLACE, AND TREATING THE PROPPING AGENT WHILE IN THE FRACTURE TO REMOVE THE COATING FROM THE CORE OF INERT MATERIAL AND LEAVE EACH CORE SEPARATED FROM ADJACENT CORES IN THE FRACTURE BY DISTANCES EQUAL TO AT LEAST THE COMBINED THICKNESS OF THE COATINGS ON ADJACENT CORES.

Claim 4

A METHOD OF TREATING AN UNDERGROUND FORMATION PENETRATED BY A WELL TO INCREASE THE FLUID FLOW CAPACITY OF SAID FORMATION INTO THE WELL COMPRISING CREATING A FRACTURE EXTENDING FROM THE WELL INTO THE FORMATION, DISPLACING INTO THE FRACTURE A PROPPING AGENT SUSPENDED IN A LIQUID TO DEPOSIT A MONOLAYER OF PROPPING AGENT IN THE FRACTURE, SAID PROPPING AGENT HAVING AN INERT CORE HAVING A STRENGTH ADEQUATE TO WITHSTAND THE OVERBURDEN PRESSURE ON THE FORMATION WITHOUT SUBSTANTIAL CRUSHING, SAID CORE BEING SURROUNDED BY A COATING OF READILY REMOVABLE SPACING MATERIAL RESISTANT TO THE LIQUID IN WHICH THE PROPPING AGENT IS SUSPENDED, SAID COATING HAVING AN THICKNESS WITHIN THE RANGE OF FROM ABOUT .01 TO ABOUT 1.0 TIMES THE DIAMETER OF THE CORE, RELEASING PRESSURE ON THE LIQUID IN THE WELL WHEREBY THE FACES OF THE FORMATION FRACTURE CLOSE TO HOLD THE PROPPING AGENT IN PLACE, AND TREATING THE PROPPING AGENT WHILE IN THE FRACTURE TO REMOVE THE COATING FROM THE CORE OF INERT MATERIAL AND LEAVE EACH CORE SEPARATED FROM ADJACENT CORES IN THE FRACTURE BY DISTANCES EQUAL TO AT LEAST THE COMBINED THICKNESS OF THE COATINGS ON ADJACENT CORES.