A cement slurry composition, containing hydraulic cement, water, and from 1 to less than 4% of an organically modified nanoclay. A method for cementing a high pressure high temperature well by pumping the cement composition of claim 1 between a casing and a formation of a well bore to fill a gap between the casing and the formation, and allowing the cement to harden.

Methods for treating and restoring zonal isolation in a subterranean well involve the use of a well treatment tool that may drill one or more holes in casing and inject a treatment fluid that may seal cracks or fissures in the cement sheath behind the casing. Microannuli may also be sealed. The treatment fluids may be solids free or in the form of suspensions containing solids having a particle size between 1 nm and 100 nm.

Embodiments of the present disclosure are directed to a method of producing a viscoelastic surfactant (VES) fluid, the VES fluid comprising desulfated seawater. The method of producing the VES fluid comprises adding an alkaline earth metal halide to seawater to produce a sulfate precipitate. The method further comprises removing the sulfate precipitate to produce the desulfated water. The method further comprises adding a VES and one or more of a nanoparticle viscosity modifier or a polymeric modifier to the desulfated seawater. Other embodiments are directed to VES fluids that maintain a viscosity greater than 10 cP at temperatures above 250° F.

Methods for reducing loss of wellbore fluid to formation may include pumping an oil-based wellbore fluid into the wellbore, where the wellbore includes an oleaginous continuous phase and a plurality of modified brine phases dispersed in the oleaginous continuous phase.

Aqueous well treatment fluids especially suited for use in far field diversion in low viscosity carrier fluids comprise water, a friction reducer, and a diverter. The diverter comprises dissolvable particulates and proppants. The dissolvable particulates have a specific gravity of from about 0.9 to about 1.6 and a particle size of about 50 mesh or less. The proppants have a specific gravity of from about 0.9 to about 1.4 and a particle size of from about 20 to about 100 mesh. The dissolvable particulates have a higher specific gravity and a smaller particle size than the proppant.

An object is to provide a dispersion of ultrafine cellulose fibers having a high thickening effect and a gelling function. There is provided a subterranean formation processing composition comprising ultrafine cellulose fibers, which has a haze value of 1.0% to 50%, when the composition is suspended in water such that the solid concentration of cellulose fibers is 0.2% by mass. The composition of the present invention can be used as an additive to the fluid at the time of the processing of subterranean formation, especially the processing of the well. The present invention provides also various fluids which are used in well processing. The present invention provides a method for processing a subterranean formation, for example, drilling of an exploratory well or a wildcat, an appraisal well, an exploratory well or an exploration well, a delineation well, a development well, a production well, an injection well, an observation well, and a service well; cementing; fracturing; and a method for producing petroleum resources.

A method of surface logging a well includes adding each of multiple polymeric taggants to a circulating drilling fluid in an addition sequence while drilling the well. Each polymeric taggant includes a polymer and a respective fluorescent dye having an emission wavelength or excitation wavelength different from that of each other fluorescent dye. The method includes taking a sample of drill cuttings carried by a drilling fluid while drilling a well, wherein the sample of drill cuttings includes polymeric taggants attached to the drill cuttings. The method includes extracting the dyes from the sample of drill cuttings into an extract solution; determining an indication of the type of and the concentration of each of the dyes in the extract solution; and determining a depth associated with the sample of drill cuttings based on the indication of the concentration of each of the dyes and on the addition sequence.

This invention is broadly concerned with compositions and processes for oilfield applications. More specifically, this invention relates to novel polymer constructed packages that, when pumped into a petroleum well, provide tunable characteristics of transformation and delayed self-assembly with each other under reservoir conditions to yield strong, elastic, bulk gel materials. The compositions comprise a polymer, assembling agents, and optional additives used for the re-assembly stage are uniformly-distributed within the initial gel particles. The polymer particle packages absorb water and swell upon exposure to water, thus exposing the “assembling agents” that enable re-assembly. Both swelling and re-assembly are proportionally controlled via compositions to be tunable to allow functional dispersion and subsequent self-assembly under various reservoir conditions.

A dispersion of capsules in critical or supercritical carbon dioxide is provided. The capsules include an aqueous solution encapsulated by 2-dimensional particles. Also provided is a method of making a dispersion of aqueous solution capsules. The method includes providing a medium of critical or supercritical carbon dioxide, introducing the aqueous solution into the critical or supercritical carbon dioxide medium, and introducing a 2-dimensional particle into the critical or supercritical carbon dioxide medium. Associated methods of using the disclosed dispersions in hydrocarbon-bearing formations are also provided.

A method of using a nanosilica-containing cement in a well cementing operation in a well, the method comprising the steps of pumping a nanosilica-containing cement formulation into the well, wherein the nanosilica-containing cement formulation comprises maltodextrin-coated nanosilica and a cement formulation, where the maltodextrin-coated nanosilica comprises nanosilica particles encapsulated by maltodextrin coating, wherein the pH of the nanosilica-containing cement formulation is between 9 and 14, maintaining a temperature in the well due to a temperature of a formation surrounding the well, wherein the disintegration of the maltodextrin coating is initiated due to the temperature and pH of the nanosilica-containing cement, exposing the nanosilica particles due to the disintegration of the maltodextrin coating from the maltodextrin-coated nanosilica, and reacting the nanosilica particles with the cement formulation such that the transition time is reduced.