Process for selectively and temporarily sealing a geological formation having zones of varying permeability

Claim 1

A PROCESS FOR SELECTIVELY INJECTING A FLUID INTO A SUBTERRANEAN ROCK FORMATION OF DIFFERENT STREAKS OF PERMEABILITY TRAVERSED BY A BORE HOLE COMPRISING FORCING INTO SAID FORMATION THROUGH SAID BORE HOLE A LIQUID HEATTRANFER MEDIUM COOLED TO A TEMPERATURE SUSTANTIALLY BELOW FORMATION TEMPERATURE WHEREBY SAID FORMATION IS COOLED TO A TEMPERATURE SUBSTANTIALLY BELOW NORMAL FORMATION TEMPERATURE, INTRODUCING INTO THE COOLED FORMATION A COLLOIDAL SOL WHICH AT THE REDUCED TEMPERTURE OF THE FORMATION SETS TO A GEL SOLATABLE UPON HEATING, RETAINING SAID SOL WITHIN SAID FORMATION UNTIL IT COOLS TO GELATING TEMPERTURE AND FORMS A GEL, ALLOWING SAID FORMATION TO HEAT FOR A PERIOD OF TIME SUFFICIENT FOR THE TEMPERATURE IN THE LESS PERMEABLE STREAKS TO REVERT TO A TEMPERTURE ABOVE THE GALATING TEMPERTURE OF SAID SOL BUT INSUFFICIENT TO ALLOW THE TEMPERTURE IN SAID MORE PERMEABLE STREAKS TO RISE TO SAID GELATING TEMPERATURE, WHEREBY SAID SOL WITH REMAIN TEMPORARILY GELATED IN SAID MORE PERMEABLE STREAKS BUT WILL REVERT TO THE SOL STATE IN SAID LESS PERMEABLE STREAKS, AND INJECTING SIAD FLUID INTO SAID LESS PERMEABLE STREAKS AFTER THE GEL THERIN HAS REVERTED TO THE SOL STATE AND THE MORE PREMEABLE STREAKS ARE TEMPORARILY SEALED BY SAID GEL.