A lost circulation material (LCM) that includes spheres having radially distributed hooks and latches to facilitate engagement (such as interlocking) of the spheres is provided. Each sphere has a plurality of hooks and a plurality of latches to engage latches and hooks respectively of adjacent spheres. Each hook may include two hook arms, and each latch may define an aperture to receive a hook arm. The spheres may form plugs in channels, fractures, and other openings in a lost circulation zone. Additionally or alternatively, the spheres may form a bridge on which other LCMs may accumulate to seal openings in a lost circulation zone. Methods of preventing lost circulation using the spheres are also provided.

Methods for breaking polymer-containing treatment fluids for use in subterranean formations are provided. In one or more embodiments, the methods include providing a treatment fluid comprising a base fluid and a polymer, wherein the treatment fluid was recovered from at least a portion of a subterranean formation located at a wellsite; transporting the treatment fluid from the wellsite to an off-site location; and applying a cavitation technique to at least a portion of the treatment fluid at the off-site location.

Wellbore fluids may contain an aqueous base fluid comprising a monovalent brine, a modified starch, and a metal oxide. Methods of using wellbore fluids may include drilling a subterranean well while circulating a wellbore fluid into the subterranean well, wherein the wellbore fluid contains an aqueous base fluid comprising a monovalent brine, a modified starch, and a metal oxide.

An invert-emulsion drilling fluid may include a dispersed aqueous phase including an aqueous base fluid, a continuous non-aqueous phase including a non-aqueous base fluid, and a first bridging package. The first bridging package may include one or more particulate carbonate materials. All of the particulate carbonate materials of the invert-emulsion drilling fluid may be part of the first bridging package. The first bridging package may have a trimodal particle size distribution such that the particle size distribution of the first bridging package includes three peaks, wherein each peak may be in the range of less than or equal to 300 microns in the particle size distribution. The invert-emulsion drilling fluid may be included in methods for reducing lost circulation in subterranean formations during drilling operations.

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.

Drilling fluid compositions and methods of using them are described. The drilling fluid compositions comprise nanocomposites comprising core-shell morphology, wherein the core material comprises a nanoparticle having an average particle size of about 5 nm to 100 nm, and the shell material comprises a crosslinked polymer comprising acrylamide repeat units. The nanocomposites are effective fluid loss control agents when the drilling fluids are employed in mud drilling operations.

An organoclay composition comprising a mineral clay mixture which has been treated with a combination of quaternary ammonium salts, said mixture comprising: mineral clay (a) comprising about 15 to about 60 wt. %, based on the weight of the mineral clay mixture, of sepiolite; mineral clay (b) comprising about 40 to about 85 wt. % based on the weight of the mineral clay mixture, of montmorillonite; an alkyl or alkenyl quaternary ammonium salt and an alkoxylated quaternary ammonium salt.

A method of hydraulic fracturing may comprise mixing at least one liquid sand mixture with a fluid to produce a fracturing fluid; and conveying the fracturing fluid to two or more wellbores simultaneously, wherein the wellbores penetrate a subterranean formation.

Methods of treating a subterranean formation and treatment fluids are discussed herein. The methods generally include treating the subterranean formation with a rare earth oxide by providing a first treatment fluid having a density of at least about 10 pounds per gallon including a rare earth oxide; and introducing the first treatment fluid into the subterranean formation.

The present disclosure provides treatment fluids that comprise star macromolecules as a fluid loss additive or a viscosifier. An embodiment of the present disclosure is a method comprising: providing a treatment fluid that comprises: an aqueous base fluid; and a star macromolecule that comprises: a hydrophilic polymeric core, a first group of polymeric arms attached to the core wherein each of the arms in the first group consists of hydrophilic monomers, and a second group of polymeric arms attached to the core wherein each of the arms in the second group comprises at least one hydrophilic homopolymeric segment and at least one hydrophobic homopolymeric segment; and introducing the treatment fluid into a wellbore penetrating at least a portion of a subterranean formation. Another embodiment of the present disclosure is a method comprising: providing a treatment fluid that comprises: a non-aqueous base fluid; and a star macromolecule that comprises: a polymeric core, a first group of polymeric arms attached to the core wherein each of the arms in the first group consists of hydrophobic monomers, and a second group of polymeric arms attached to the core wherein each of the arms in the second group comprises at least one hydrophobic homopolymeric segment and at least one hydrophilic homopolymeric segment; and introducing the treatment fluid into a wellbore penetrating at least a portion of a subterranean formation.