Abstract: Methods are provided that include a method comprising providing magnesium oxide; placing the magnesium oxide within a portion of a subterranean formation; contacting the magnesium oxide with a brine that comprises water and a divalent salt; and allowing the magnesium oxide and brine to react to form a hardened mass in the portion of the subterranean formation. In some embodiments, the methods comprise providing a subterranean drilling fluid that comprises magnesium oxide; and adding a divalent salt to the subterranean drilling fluid to form a settable composition. In other embodiments, the methods comprise providing a subterranean drilling fluid that comprises magnesium oxide; and adding a divalent salt to the subterranean drilling fluid to form a settable composition. Additional methods are also provided.

Abstract: The present invention relates to settable compositions that comprise magnesium oxide and at least one divalent salt and associated methods of use. In some embodiments, the present invention discloses methods of a forming a hardened mass comprising providing a settable composition comprising magnesium oxide, and a brine comprising water and a divalent salt; placing the settable composition into a desired location; and allowing the settable composition to set to form the hardened mass. In other embodiments, the present invention discloses methods of forming a hardened mass in a subterranean formation comprising placing a brine comprising water and a divalent salt into the subterranean formation; contacting the brine with magnesium oxide; and allowing the brine and the magnesium oxide to react to form the hardened mass. In other embodiments, the present invention discloses methods forming a casing in a well bore, and converting a drilling fluid to a settable composition.

Abstract: A method for using an invert emulsion fluid in a well bore, comprising placing an invert emulsion fluid in a well bore, wherein the invert emulsion fluid comprises an oleaginous fluid, a non-oleaginous fluid and an emulsifier comprising one or more amines generally represented by the formula: wherein R is a radical selected from the group consisting of abietyl, hydroabietyl, dihydroabietyl, tetrahydroabietyl, and dehydroabietyl, each R? may be the same or different and is an alkyl having from about 1 to about 3 carbons, each A may be the same or different and is NH or O, and the sum of x and y ranges from about 1 to about 20, and contacting the invert emulsion fluid with an acid solution to reversibly convert the invert emulsion to an oil-in-water emulsion.

Abstract: An invert emulsion fluid, method for making same, and method for using same as a servicing fluid in a well bore. The invert emulsion fluid contains an oleaginous fluid, a non-oleaginous fluid, and an emulsifier comprising one or more amines generally represented by the formula: wherein R is a cycloaliphatic hydrocarbon, each R? may be the same or different and is H or an alkyl having from about 1 to about 3 carbon atoms, each A may be the same or different and is NH or O, and the sum of x and y ranges from about 1 to about 20. In a preferred embodiment, R is a radical selected from the group consisting of abietyl, dihydroabietyl, tetrahydroabietyl, and dehydroabietyl, R? is H, and A is O.

Abstract: An invert emulsion fluid, method for making same, and method for using same as a servicing fluid in a well bore.