A method of treating a well that includes introducing a well treatment fluid into the well, and a well treatment fluid, are provided. The well treatment fluid comprises an aqueous base fluid, a bridging agent, a viscosifying agent, and a water soluble, biodegradable graft copolymer. In one embodiment, for example, the method is a method of cementing a casing in a well. In this embodiment, the well treatment fluid is a cement spacer fluid.

A drilling fluid formulation is provided, which includes an aqueous base fluid, a synthetic modified phyllosilicate as an anti-sagging additive, an inorganic base, and a weighting agent (e.g. barite). The synthetic modified phyllosilicate contains a clay material (e.g. smectite) and a metal selected from ruthenium, rhodium, palladium, osmium, iridium, and platinum. The synthetic modified phyllosilicate is effective in preventing barite sagging as demonstrated by low sag factor when drilling at elevated temperatures. Rheology properties of the drilling fluid including gel strength, yield point, plastic viscosity, and storage modulus are also specified.

A method of drilling a subterranean geological formation is described. The method includes driving a drill bit to form a wellbore into the subterranean geological formation thereby producing a formation fluid including hydrogen sulfide (H.sub.2S). The method includes injecting a drilling fluid into the subterranean geological formation through the wellbore. The drilling fluid composition includes 0.25 to 2 wt. % of a primary H.sub.2S scavenger which is potassium permanganate. The drilling fluid composition includes an invert emulsion which includes a continuous phase including mineral oil and a dispersive phase including water. The potassium permanganate present in the drilling fluid composition reacts with the H.sub.2S present in the formation fluid to produce a dispersion of manganese-containing particles which are at least one selected from the group consisting of manganese sulfide and manganese sulfate.

Described herein are methods of enhancing the rheological properties of a colloidal mineral suspension in a liquid with high-intensity acoustical energy. In some examples, the colloidal mineral suspension may be dehydrated after treatment with high-intensity acoustical energy.

Provided is a lubricant, which may include a mixture of alkyl-esterified fatty acids from waste vegetable oil and a C8/C10 fatty acid blend. The C8/C10 fatty acid blend may include a caprylic fatty acid (C8) and a capric fatty acid (C10). Provided is a method of preparing a lubricant, which may include providing alkyl-esterified fatty acids from waste vegetable oil and a C8/C10 fatty acid blend, and mixing them such that a homogeneous lubricant composition forms. Further provided is a water-based mud, which may include an aqueous base solution and a lubricant composition. Further provided is a method off preparing the water-based mud, which may include providing an aqueous base solution and a lubricant composition and mixing them such that the water-based mud forms. Further provided is a method of using a water-based mud, which may include introducing into a wellbore the water-based mud comprising a lubricant composition.

Methods and compositions for a rheologically modified well fluid are provided. A method includes combining an amount of a synthetic functionalized additive with an intermediate well fluid composition to form a synthetic functionalized additive-containing well fluid composition, and subjecting the synthetic functionalized additive-containing well fluid composition to shear stress for a period of time such that the synthetic functionalized additive-containing well fluid composition is rheologically modified to produce the rheologically modified well fluid. The synthetic functionalized additive comprises a synthetic layered magnesium silicate that is covalently bonded to a functional group, and the intermediate well fluid composition comprises a water-based continuous phase.

A water-based drilling fluid having spent jet-engine oil as a lubricant. A system and method for utilizing the spent jet-engine oil and the water-based drilling fluid to drill a borehole in a subterranean formation in the Earth crust.

Provided is a lubricant, which may include a mixture of alkyl-esterified fatty acids from waste vegetable oil and a C8/C10 fatty acid blend. The C8/C10 fatty acid blend may include a caprylic fatty acid (C8) and a capric fatty acid (C10). Provided is a method of preparing a lubricant, which may include providing alkyl-esterified fatty acids from waste vegetable oil and a C8/C10 fatty acid blend, and mixing them such that a homogeneous lubricant composition forms. Further provided is a water-based mud, which may include an aqueous base solution and a lubricant composition. Further provided is a method off preparing the water-based mud, which may include providing an aqueous base solution and a lubricant composition and mixing them such that the water-based mud forms. Further provided is a method of using a water-based mud, which may include introducing into a wellbore the water-based mud comprising a lubricant composition.

Compositions and methods for inhibiting dissolution of carbonates in a subterranean formation are provided. In some embodiments, the methods comprise: providing a treatment fluid that comprises a base fluid and a carbonate dissolution inhibiting additive; contacting a portion of a carbonate-bearing subterranean formation with the treatment fluid; and allowing the carbonate dissolution inhibiting additive to chemically interact with the portion of the carbonate-bearing subterranean formation to inhibit dissolution of one or more carbonate minerals in the formation, whereby the susceptibility of at least a portion of the carbonate-bearing subterranean formation to fluid-induced damage is decreased.

Compositions and methods for inhibiting dissolution of carbonates in a subterranean formation are provided. In some embodiments, the methods comprise: providing a treatment fluid that comprises a base fluid and a carbonate dissolution inhibiting additive; contacting a portion of a carbonate-bearing subterranean formation with the treatment fluid; and allowing the carbonate dissolution inhibiting additive to chemically interact with the portion of the carbonate-bearing subterranean formation to inhibit dissolution of one or more carbonate minerals in the formation, whereby the susceptibility of at least a portion of the carbonate-bearing subterranean formation to fluid-induced damage is decreased.