Methods of suspending at least one weighting agent in drilling fluids. The embodiments include adding a quantity of precursor nanoparticles including carbon nanotubes supported by metal oxide catalyst nanoparticles to the drilling fluid. The metal oxide catalyst nanoparticles and the drilling fluid are selected such that the metal oxide catalyst nanoparticles are dissolvable in the drilling fluid. The metal oxide catalyst nanoparticles dissolve in the drilling fluid, resulting in an amount of carbon nanotubes dispersed within the drilling fluid. The carbon nanotube dispersion increases the value of at least one of a Newtonian viscosity, a yield point, a plastic viscosity, and a density of the drilling fluid with the dispersed carbon nanotubes versus a similar or equivalent drilling fluid without the carbon nanotube dispersion. The method may further include adding at least one weighting agent which will become suspended in the drilling fluid.

Magnetically responsive drilling fluids and methods of using magnetically responsive drilling fluids. The magnetically responsive drilling fluids may include a drilling fluid and a plurality of superparamagnetic nanostructures disposed within the drilling fluid. The plurality of superparamagnetic nanostructures may include superparamagnetic-iron-oxide-nanoparticles (SPIONs) and carbon nanotubes (CNTs) adsorbed onto the SPIONs. The method of using the magnetically responsive drilling fluid may include introducing the magnetically responsive drilling fluid into a subsurface formation and applying a magnetic field to the magnetically responsive drilling fluid to elicit a rheological change in the magnetically responsive drilling fluid.

In one embodiment, a retarded acid system comprises an aqueous acid and a retarding surfactant. The aqueous acid may comprise from 5 wt. % to 25 wt. % of a strong acid, that is, an acid having a K.sub.a greater than or equal to 0.01. The aqueous acid may further comprise from 75 wt. % to 95 wt. % water. The retarding surfactant may have the general chemical formula R—(OC.sub.2H.sub.4).sub.X—OH where R is a hydrocarbon having from 11 to 15 carbon atoms and x is an integer from 6 to 10. The retarding surfactant may have a hydrophilic-lipophilic balance from 8 to 16.

Methods and compositions for treating subterranean formations with fluids containing lost circulation materials are provided. In one embodiment, the methods introducing a treatment fluid that includes a base fluid and a lost circulation material into a wellbore penetrating at least a portion of a subterranean formation, wherein the lost circulation material includes a plurality of particles having a multi-modal particle size distribution comprising a d10 value ranging from about 20 to about 50 microns, a d50 value ranging from about 55 to about 90 microns, and d90 value ranging from about 240 to about 340 microns.

A lost circulation material (LCM) is provided having an alkaline nanosilica dispersion and an ester activator. The alkaline nanosilica dispersion and the ester activator may form a gelled solid after interaction over a contact period. Methods of lost circulation control using the LCM are also provided.

A fiber silica composite microsphere for a shale stratum comprises a hollow silica sphere and fibers, and the fibers are partially coated on an outer surface of the hollow silica sphere and partially embedded into an interior of the hollow silica sphere. The hollow silica sphere has an outer diameter of 1-5 μm and an inner diameter of 0.8-4.7 μm; the fibers have a length of 5-10 μm and a width of 1-3 μm.

The present invention relates to drilling fluids which reduce fluid and cutting loss during the drilling of subterranean wells. More specifically, the drilling fluids disclosed herein comprise natural and synthetic polymer blends that are effective to provide the fluid with a high viscosity under low shear rates and a low viscosity under high shear rates. The present invention also relates to methods for using the drilling fluids for reducing fluid and cutting loss during drilling.

Methods of determining the integrity of a well are provided. The methods include mixing conductive materials into a fluid, introducing the fluid into the well, and allowing the conductive materials to coat a surface of a subsurface formation, thereby forming an electrically conductive data conduit coating. The methods further include transmitting data through the electrically conductive data conduit coating to determine the integrity of the well.

A method of increasing a solubility of a manganese oxide includes contacting the manganese oxide with an acid component in the presence of a dissolution accelerator that includes at least one of hydrazine, a hydrazine derivative, or a hydrazide. Also disclosed is a drilling fluid containing a carrier; MnO.sub.2; and at least one of a viscosifier, a rheology modifier, a dispersant, a weighting agent, a defoamer, a fluid loss agent, bentonite, or a lubricant.

Embodiments of treating fluid comprising hydrocarbons, water, and polymer being produced from a hydrocarbon-bearing formation are provided. One embodiment comprises adding a concentration of a viscosity reducer to the fluid to degrade the polymer present in the fluid and adding a concentration of a neutralizer to the fluid to neutralize the viscosity reducer in the fluid. The addition of the concentration of the viscosity reducer is in a sufficient quantity to allow for complete chemical degradation of the polymer prior to the addition of the concentration of the neutralizer in the fluid such that excess viscosity reducer is present in the fluid. The addition of the concentration of the neutralizer is sufficiently upstream of any surface fluid processing equipment to allow for complete neutralization of the excess viscosity reducer such that excess neutralizer is present in the fluid prior to the fluid reaching any of the surface fluid processing equipment.