Abstract: The disclosed invention is a novel drilling fluid additive for use in reducing lost circulation in wellbores and a method for employing the invention additive for reducing such lost circulation. The invention additive is a highly oil absorbent polymer encapsulated by a reaction-preventive protective casing to prevent the polymer from expanding by absorbing oil until it is desired to breach the casing. The reaction-preventive protective casing may be a film which will dissolve after a desired time of residence in the borehole or a film or clay which can be ruptured in the formation, releasing the oil absorbent polymer to expand by absorbing oil. The substantially expanded polymer will seal off their zones and fissures, reducing lost circulation.

Abstract: The disclosed invention is a novel drilling fluid additive for use in reducing lost circulation in wellbores and a method for employing the invention additive for reducing such lost circulation. The invention additive is a highly water absorbent polymer encapsulated by a reaction-preventive protective casing to prevent the polymer from expanding by absorbing water until it is desired to breach the casing. The reaction-preventive protective casing may be a film which will dissolve after a desired time of residence in the borehole or a film or waxy substance which will dissolve or melt at a desired temperature in the borehole, releasing the water absorbent polymer to expand by absorbing water. The substantially expanded polymer will seal off thief zones and fissures, reducing lost circulation.

Abstract: The invention is a method for reducing lost circulation of aqueous or oil based drilling fluids wherein one or more water absorbent polymers are dispersed in a hydrocarbon fluid which is injected into the lost circulation zone. The hydrocarbon carrier fluid initially prevents water from contacting the water absorbent polymer until such water contact is desired. Once the hydrocarbon slug containing the polymer is properly placed at the lost circulation zone, water is mixed with the hydrocarbon slug so that the polymer will expand with the absorbed water and substantially increase in size to close off the lost circulation zone.

Abstract: The invention is a method for reducing lost circulation of aqueous or oil based drilling fluids wherein one or more hydrocarbon absorbent polymers are dispersed in an aqueous carrier fluid which is injected into the lost circulation zone. The aqueous carrier fluid initially prevents hydrocarbon from contacting the hydrocarbon absorbent polymer until such contact is desired. Once the aqueous polymer slug is properly placed at the lost circulation zone, a hydrocarbon is mixed with the aqueous slug so that the polymer will expand with the absorbed hydrocarbon and substantially increase in size to close off the lost circulation zone.

Abstract: The disclosed invention is a novel drilling fluid additive for use in reducing lost circulation in wellbores and a method for employing the invention additive for reducing such lost circulation. The invention additive is lime encapsulated by a reaction-preventive protective casing to prevent the lime from reacting with clays in the borehole until it is desired to breach the casing. The reaction-preventive protective casing may be a film which will dissolve after a desired time of residence in the borehole or a film or waxy substance which will dissolve or melt at a desired temperature in the borehole, releasing the lime to react with clays in the formation or in the borehole to form a cement-like mass.

Abstract: A method is revealed for releasing a stuck drill string in a borehole of an underground formation by application of an additive fluid comprising a lower carbon number alcohol and optionally a weighting material and/or diluent.

Abstract: A method is revealed for releasing a stuck drill string in a borehole of an underground formation by application of an additive fluid comprising fresh water or brine and a polymer material.

Abstract: Disclosed is a method for treating subterranean formations such as underground petroleum-containing formations penetrated by a well, and particularly a formation penetrated by a producing well which formation contain a plurality of zones, one or more of which are producing petroleum and one or more of which are producing water. The treatment selectively reduces the permeability of the water-producing intervals without adversely affecting the permeability of the oil producing intervals, thereby reducing the production of water and reducing the water-oil ratio of the fluid being produced from the well. The treatment method involves introducing an effective amount of a liquid comprising a hydrocarbon having dispersed therein an unhydrated water swellable clay such as bentonite, a sodium montmorillonite. The clay swells on contacting water in the water-producing intervals and plugs or reduces the permeability of the flow channels in the water-producing intervals.

Abstract: An additive composition effective in the release of stuck pipe in a bore hole during a drilling operation.

Abstract: Aqueous drilling fluids containing a minor amount of an additive composition. Such fluids are especially useful where reduced torque drilling fluids are needed. Another embodiment of this invention relates to a method of drilling utilizing the above-described fluids.The additive is a composition containing a particular emulsifying agent, a petroleum oil carrier, tetraethylene oxide -- nonyl phenol adduct, ethylene glycol monobutyl ether, hexahydro 1, 3, 5-triethyl -s-triazine, tri-isopropanolamine and optionally ditertiary alkyl polysulfide, a chlorinated hydrocarbon, and zinc dialkyl dithiophosphate.

Abstract: An aqueous low solids drilling fluid especially suitable for drilling sloughing, mud yielding shale formations. The drilling fluid has an A.P.I. filtration rate in excess of 100 milliliters, a soluble calcium level in excess of 200 and preferably in excess of 1000 parts per million, a filtrate alkalinity greater than 0.1 milliliters of .02 N sulfuric acid per milliliter of filtrate, at least one pound per barrel excess or undissolved calcium hydroxide, a salinity of at least 50,000 parts per million and a ratio of plastic viscosity to yield point not greater than one.

Abstract: Method of and composition for the treatment of an aqueous drilling fluid containing contaminating amounts of salt whereby the rheological properties of the aqueous fluid are improved by treatment with a polyethylene glycol in the molecular weight range of from about 200 to 500.