Abstract: The present invention provides a method of treating a subterranean formation utilizing a gelled fluid containing a galactomannan gum and a crosslinking agent comprising a source of borate ions and a delayed crosslinker comprising a source of Ti(+4) or Zr(+4) ions. The combination of crosslinking agents yields a viscous fluid at elevated temperatures having a viscosity higher than attainable by either crosslinking agent alone or as the result of the additive effects of the crosslinking agents. The enhanced viscosity facilitates transport and placement of proppant material in a subterranean formation.

Abstract: A method of treating a subterranean formation with delayed crosslinking gel fluids is provided. An aqueous gel is first prepared by admixing an organic carboxylated gelling agent with an aqueous liquid. A buffer is combined with the aqueous gel in an amount sufficient to result in and maintain the pH thereof at a level of about 5 or above at ambient temperature. A zirconium IV-containing crosslinking compound is combined with the gel and the mixture is introduced into a subterranean formation whereby the mixture is heated and caused to crosslink.

Abstract: The present invention relates to a method of fracturing subterranean formations and placing proppant material in the created fracture utilizing carbon dioxide or nitrogen containing fluid. An aqueous liquid-liquid carbon dioxide emulsion fluid is prepared having an internal phase ratio in the range of from about 50 to in excess of about 96 percent and introduced into the subterranean formation to be fractured. The emulsion is heated by the formation to a temperature above the critical temperature of carbon dioxide and the carbon dioxide is caused to be converted to a vapor whereupon the emulsion becomes a foam. The volume of liquid carbon dioxide is adjusted as the volume of proppant material varies to at least substantially maintain a constant internal phase ratio in the treatment fluid. When nitrogen is utilized, a foam is produced on the surface by admixing gaseous nitrogen with the gelled fluid. The formation is fractured by the treatment fluid and the proppant is placed in the created fracture.

Abstract: A method of fracturing a subterranean formation with a stabilized foamed fracturing fluid comprising from about 30 percent to in excess of about 95 percent by volume of carbon dioxide with the remainder comprising a substantially anhydrous liquid and a selected surfactant. The foam is formed in situ by injection of a stabilized liquid-liquid emulsion containing liquid carbon dioxide into a well bore penetrating the formation. The temperature and pressure of the emulsion is controlled to maintain the carbon dioxide in the liquid phase during injection into the well bore. Thereafter, the carbon dioxide is heated by the subterranean formation to a temperature above about 88.degree. F. at which time the stabilized emulsion spontaneously forms a high quality stabilized foam.

Abstract: A method of fracturing a subterranean formation with a stabilized foamed fracturing fluid comprising from about 30 percent to in excess of about 95 percent by volume of carbon dioxide with the remainder comprising a substantially anhydrous liquid and a selected surfactant. The foam is formed in situ by injection of a stabilized liquid-liquid emulsion containing liquid carbon dioxide into a well bore penetrating the formation. The temperature and pressure of the emulsion is controlled to maintain the carbon dioxide in the liquid phase during injection into the well bore. Thereafter, the carbon dioxide is heated by the subterranean formation to a temperature above about 88.degree. F. at which time the stabilized emulsion spontaneously forms a high quality stabilized foam.

Abstract: A method of fracturing a subterranean formation with a stabilized foamed fracturing fluid comprising from about 50 percent to in excess of about 96 percent by volume of carbon dioxide with the remainder comprising an aqueous liquid and a selected surfactant. The foam is formed in situ by injection of a stabilized liquid-liquid emulsion containing liquid carbon dioxide into a well bore penetrating the formation. The temperature and pressure of the emulsion is controlled to maintain the carbon dioxide in the liquid phase during injection into the well bore. Thereafter, the carbon dioxide is heated by the subterranean formation to a temperature above about 88.degree. F. at which time the stabilized emulsion spontaneously forms a high quality stabilized foam.

Abstract: Highly stable high alcohol content foams are provided which include a foam-forming surfactant represented by the formula ##STR1## Methods of forming and using the alcohol foams are also provided.

Abstract: A method of fracturing a subterranean formation with a stabilized foamed fracturing fluid comprising from about 50 percent to in excess of about 96 percent by volume of carbon dioxide with the remainder comprising an aqueous liquid and a selected surfactant. The foam is formed in situ by injection of a stabilized liquid-liquid emulsion containing liquid carbon dioxide into a well bore penetrating the formation. The temperature and pressure of the emulsion is controlled to maintain the carbon dioxide in the liquid phase during injection into the well bore. Thereafter, the carbon dioxide is heated by the subterranean formation to a temperature above about 88.degree. F. at which time the stabilized emulsion spontaneously forms a high quality stabilized foam.