Treatment of oil-bearing formations

Claim 1

THE METHOD OF DIFFERENTIALLY SHUTTING OFF WATER IN AN OIL PENETRATING BOTH OIL-AND WATER-BEARING FORMATIONS WHICH COMPRISES FORCING DOWN THE WELL AND INTO SAID FORMATION A PLUGGING COMPOSITION COMPRISING AN ORGANIC SOLVENT HAVING DISSOLVED THEREIN BETWEEN ABOUT 0.5 AND ABOUT 10 PER CENT BY WEIGHT OF A WATER-INSOLUBLE CELLULOSE DERIVATIVE SELECTED FROM THE CLASS CONSISTING OF CELLULOSE NITRATE, CELLULOSE ETHERS OF ALCOHOLS CONTAINING LESS THAN FIVE CARBON ATOMS AND CELLULOSE ESTERS OF ACIDS CONTAINING LESS THAN FIVE CARBON ATOMS, BETWEEN ABOUT 0.1 AND ABOUT 5 PER CENT BY WEIGHT OF AN ALKYL SILICATE, THE ALKYL GROUP OF WHICH CONTAINS LESS THAN FIVE CARBON ATOMS AND BETWEEN ABOUT 0.1 AND ABOUT 5 PER CENT BY WEIGHT OF AN OIL-SOLUBLE RESIN; ALLOWING THE FORMATION FLUIDS TO ACT UPON SAID COMPOSITION, WHEREBY SAID FORMATIONS ARE RENDERED LESS PERMEABLE TO WATER FLOW THAN TO OIL FLOW; AND THEREAFTER REMOVING UNCHANGED PLUGGING COMPOSITION FROM SAID WELL.

Claim 2

THE METHOD OF DIFFERENTIALLY SHUTTING OFF WATER IN AN OIL PENETRATING BOTH OIL-AND WATER-BEARING FORMATIONS WHICH COMPRISES FORCING DOWN THE WELL AND INTO SAID FORMATION A PLUGGING COMPOSITION COMPRISING AN ORGANIC SOLVENT HAVING DISSOLVED THEREIN BETWEEN ABOUT 0.5 AND ABOUT 10 PER CENT BY WEIGHT OF A WATER-INSOLUBLE CELLULOSE DERIVATIVE SELECTED FROM THE CLASS CONSISTING OF CELLULOSE NITRATE, CELLULOSE ETHERS OF ALCOHOLS CONTAINING LESS THAN FIVE CARBON ATOMS AND CELLULOSE ESTERS OF ACIDS CONTAINING LESS THAN FIVE CARBON ATOMS, BETWEEN ABOUT 0.1 AND ABOUT 5 PER CENT BY WEIGHT OF AN ALKYL SILICATE, THE ALKYL GROUP OF WHICH CONTAINS LESS THAN FIVE CARBON ATOMS AND BETWEEN ABOUT 0.1 AND ABOUT 5 PER CENT BY WEIGHT OF AN OIL-SOLUBLE RESIN; ALLOWING THE FORMATION FLUIDS TO ACT UPON SAID COMPOSITION, WHEREBY SAID FORMATIONS ARE RENDERED LESS PERMEABLE TO WATER FLOW THAN TO OIL FLOW; AND THEREAFTER REMOVING UNCHANGED PLUGGING COMPOSITION FROM SAID WELL.