Methods of enhancing water injectivity into a subterranean wellbore may include injecting a first composition comprising nitrate anions having a nitrate concentration into a target zone of the subterranean wellbore; injecting a second composition comprising nitrate anions into the target zone of the subterranean wellbore, where the second composition has a nitrate concentration of from about 20% to about 70% the nitrate concentration of the first composition; optionally injecting a third composition comprising nitrate anions into the target zone of the subterranean wellbore, where the third composition has a nitrate concentration of from about 20% to about 70% the nitrate concentration of the second composition; and injecting water, where the water injection pressure is reduced by about 5% to 25% compared to the water injection pressure in an untreated subterranean wellbore, where the nitrate anions are reduced by bacteria present in the subterranean wellbore.

The present invention relates to friction reducers and to well treatment fluids. In one embodiment there is provided a friction reducing composition comprising (a) a phosphonium compound and (b) a polymeric friction reducer. In a further embodiment there is provided a well treatment fluid comprising a phosphonium compound.

Methods of fracturing a subterranean formation include introducing a fracturing fluid containing an aqueous medium, a viscosifying agent and a polyethylene oxide alkyl ether through a wellbore and into the subterranean formation, pressurizing the fracturing fluid to fracture the subterranean formation, and allowing the fracturing fluid to flow back into the wellbore from the subterranean formation. The polyethylene oxide alkyl ether useful in some embodiments is defined according to the formula: where R.sub.1 and R.sub.2 are independently selected from linear or branched alkyl groups having from 2 to 16 carbon atoms, and ‘n’ may be a value selected from within a range of from 1 to 100.

Formulations and methods for stimulating the production from wells in nano-darcy shale formations. In one embodiment, the method includes injecting a treatment mixture containing a metal complexing agent into a nano-darcy shale formation adjacent to a well at a pressure below the fracture pressure of the formation. A sufficient contact time is allowed and then the treatment mixture is pumped from the subsurface. This has been shown to stimulate well production in shale formations. Without being held to a particular theory it appears that the metal complexing agent is binding with naturally occurring metals in the shale formation, and particularly divalent metal ions, which are then extracted with the spent fluid. This removal of naturally occurring metals may be increasing the permeability of the formation in the contact region adjacent to the well, thereby causing the observed increased production.

Provided is a method for hydraulic fracturing in a borehole in a geological formation using a process fluid including an environmentally friendly biostabiliser. The biostabiliser is characterised in that it includes at least one organic acid, or a salt, alcohol or aldehyde thereof, such that the at least one organic acid is selected from the hop acids, resin acids, fatty acids and mixtures thereof.

A biocide blend can be used in an oil or gas operation. The biocide blend can include a first biocide of a formaldehyde-releasing biocide and a second biocide of a quaternary ammonium compound. The formaldehyde-releasing biocide can release formaldehyde after introduction into a wellbore. The first and second biocide can possess at least one property that is the same. The first biocide and/or the second biocide can maintain biocidal activity for extended periods of time in high salinity wellbore fluids, be thermally stable, and less expensive than other biocides.

Proppants are used in oil and gas extraction, particularly in fracking operations. The invention relates to resin coated proppants. The coatings on proppants have antimicrobial materials incorporated within these coatings. The antimicrobially active agents are incorporated in a concentration less than 70% by weight of the coatings or the active agent from these coatings can be released from these coatings in the environment of the proppants.

A well treatment fluid composition that includes a tetrakis(hydroxyorgano)phosphonium salt and 1,3-dimethylol-5,5-dimethylhydantoin. Methods for preparing a well treatment fluid composition and treating a subterranean formation are also presented.

The present disclosure discloses a one-component type multi-functional fracturing fluid additive and a process for preparing the same. The process the following steps: mixing ethylene glycol, isopropanol, 1-butanol, 1-hexanol and 1-octanol, and heating to uniformly disperse the mixture to obtain an aqueous dispersant; adding a high molecular polymer thickener and an auxiliary agent to the aqueous dispersant, and stirring the mixture at a high speed to obtain a suspension, wherein the auxiliary agent is one or more selected from clay stabilizers, drainage aids, drag reducers, emulsion inhibitors, filtrate reducers, corrosion inhibitors and fungicides; and slowly stirring the suspension at a low speed, and cooling the suspension to room temperature to collect a sample of suspension. This auxiliary agent has good characteristics such as temperature resistance, shear resistance, salt resistance, and sand suspension.

A multiple-loaded non-ceramic dry carrier product and method for the loading of reagent liquids, solids dissolved in liquids as solutions, suspensions, and solids heated to reduce viscosity, onto perlite, pumice, scoria, or exfoliated vermiculite or activated charcoal particles, which are used as carriers, and then dried in multiple iterations to achieve a powdered, free-flowing material for use in hydraulic fracturing processes and other uses such as environmental remediation and animal control, providing improvements in cost, carrier stability, and chemical retention properties.