A method for temporary isolation of a well interval is proposed, the method comprising: pumping a first slurry into the well, the slurry comprising a viscous carrier fluid, degradable particulates, and degradable fibers, until a first filter cake is formed; and pumping a second slurry into the well, the slurry comprising a viscous carrier fluid, non-degradable particulates, and degradable fibers, until a second filter cake is formed. The first and the second slurries are not mixed when pumped into the well. To ensure optimum interval isolation, the ratio of the volume of the first slurry to the volume of the second slurry should be in the range 1:5 to 2:1. A method for hydraulic refracturing within an interval with several hydraulic fractures and a non-damaging well killing method are also proposed. The technical result is manifested in no formation damage and degradation of the sealing layer formed.

The present invention generally relates to the composition of particle gels for CO.sub.2-EOR and CO.sub.2 storage. More particularly, CO.sub.2 resistant particle gels are provided that can re-crosslink at subterranean conditions. These particle gels can be deployed to improve the conformance of CO.sub.2 flooding, CO.sub.2 huff-puff, or Water-Alternative-Gas (WAG). The applications may also involve CO.sub.2 storage, such as the blocking of CO.sub.2 leakage and similar CO.sub.2 processing.

This invention relates to the field of techniques for treating subterranean formations with gels during an oil or gas exploration or production operation, i.e., during drilling, completion, or hydraulic fracking processes. The invention relates in particular to a system making it possible to limit or even inhibit the phenomena known as loss of fluids (wager and/or gas) in an underground formation, particularly in a zone where the temperature is high. More particularly, the invention relates to a suspension (S) comprising: an aqueous phase containing salts; and within said aqueous phase, particles (p) based on associative polymers (P).

The invention relates to the field of oilfield development engineering, and discloses a self-growing gel dispersion active fluidity control system and a fluid channeling control method for a low-permeability-tight reservoir. The system contains 100 parts by weight of a self-growing gel dispersion and 0.15-0.6 part by weight of a surfactant, the self-growing gel dispersion is prepared by shearing and grinding nano-reinforced chromium-aldehyde double-group cross-linked integral gel, and the preparation method of the nano-reinforced chromium-aldehyde double-group cross-linked integral gel comprises the following steps: adding a functional polymer, a phenolic resin cross-linking agent, are organic chromium cross-linking agent and a nano-reinforcer into water, mixing, and curing. The system can be simply and rapidly prepared, is easy for deep injection by adjusting the size of gel dispersion particles, is wide in action range, high in stability and long in effective period of action, can avoid reservoir pollution, and does not affect the liquid production capacity of the reservoir. The gel dispersion particles can achieve self-growth in the low-permeability-tight reservoir fractures, and the fracture fluid channeling control effect is enhanced.

A method including forming a hydrophobic film on one or more surfaces as part of a geothermal operation in which a circulating fluid comprising water is injected into an injection well, absorbs heat, and is recovered from a production well prior to extraction of at least a portion of the heat therefrom and recycle of the circulating fluid back to the or another injection well.

A solids-control fluid for controlling flow of solids in a subterranean formation is disclosed herein. The solids-control fluid can include a diluent and a curable resin. The diluent can include a mutual solvent and an ethylene glycol. The curable resin can be dispersed within the diluent for controlling flow of solids in the subterranean formation.

A reversible gel composition including nanosilica and polyethylene oxide, the nanosilica and polyethylene oxide present at concentrations operable to allow for the reversible gel composition to be a flowable liquid at pH greater than about 8 and operable to allow for the reversible gel composition to be a substantially solid gel at pH less than about 8.

Water-based drilling fluids may include an aqueous base fluid and a mixture of polyethylene polyamines in an amount of from 1 lb.sub.m/bbl to 20 lb.sub.m/bbl relative to the total volume of the water-based drilling fluid. The polyethylene polyamines of the mixture may have a first chemical structure H.sub.2NCH.sub.2CH.sub.2(NHCH.sub.2CH.sub.2).sub.xNH.sub.2, where x may be an integer greater than or equal to 3. The average molecular weight of the polyethylene polyamines in the water-based drilling fluid having the first chemical structure may be from 200 g/mol to 400 g/mol. Methods for drilling a subterranean well with the water-based drilling fluids are also disclosed.

Methods of treating a subterranean formation include providing a treatment fluid including a composition of a borate salt, an amine, and an organosilane; introducing the treatment fluid into the formation; and curing the composition to at least partially consolidate unconsolidated particulates in the formation.

A method of reducing lost circulation in a wellbore includes introducing a fluid including a fluid loss control additive comprising shape memory polymer, shape memory alloy, or both into the wellbore. The method further includes allowing the fluid loss control additive to lodge within fractures within a subsurface formation in the wellbore. The method further includes allowing the fluid loss control additive to expand within the fractures, thereby forming a barrier between the wellbore and the subsurface formation to reduce lost circulation in the wellbore.