Freeing stuck pipe

Claim 1

IN A WELL OPERATION WHEREIN A WELL FLUID IS CIRCULATED THROUGH A DRILL STEM IN A WELL, A CAKE OF WATER-WET WELL FLUID SOLIDS ACCUMULATES ON THE FACE OF A PERMEABLE FORMATION PENETRATED BY THE WELL BORE, AND THE DRILL STEM BECOMES STUCK AGAINST THW CAKE OF WATER-WET SOLIDS BY A DIFFERENTIAL IN HYDROSTATIC PRESSURE BETWEEN FLUID IN THE WELL AND IN THE PERMEABLE FORMATION APPLIED ACROSS THE DRILL STEM, THAT IMPROVEMENT WHICH COMPRISES SUBSTANTIALLY FILLING THE WELL BORE OUTSIDE THE DRILL STEM IN THE PERMEABLE FORMATION WITH A PETROLEUM OIL CONTAINING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF 2-HEPTADECENYL-4-4-DIMETHYOXY-2-OXAZOLINE, 2-HEPTADECENYL-4-METHOXY4-METHYL-2-OXAZOLINE, THE SODIUM SALT OF DIOCTYL SULFOSUCCINATE, A MIXTURE OF A PRODUCT CONTAINING HIGH MOLECULAR WEIGHT FREE FATTY ACIDS, ESTERS AND ALCOHOLS MADE BY ACID CRACKING WOOL GREASE WITH ABOUT ONE-FOURTH ITS WEIGHT OF THE SODIUM SALT OF SULFATED OLEYL ALCOHOL, AND MIXTURES THEREOF, IN QUANTITY SUFFICIENT TO REDUCE INTERFACIAL TENSION AT AN INTERFACE BETWEEN THE PETROLEUM OIL AND WATER TO NOT MORE THAN 2 DYNES PER CENIMETER; DISSOLVING WATER FROM THE CAKE OF WATER-WET SOLIDS IN THE PETROLEUM OIL IN QUANTITY TO CRACK THE CAKE BY DEHYDRATION, PASSING PETROLEUM OIL FROM THE WELL BORE THROUGH THE RESULTING CRACKED CAKE TO THE PERMEABLE FORMATION, WHEREBY THE DIFFERENTIAL PRESSURE ACROSS THE DRILL STEM IS DECREASED; AND RELEASING THE DRILL STEM.