New formulation for pyrite scale removal from oil and gas wells and a method of pyrite scale removal are disclosed. The chemical formulation is composed of K.sub.2B.sub.4O.sub.7-4H.sub.2O, in a concentration of about 9-20 wt. % of the composition, preferably about 14 wt. % of the composition. The new formulation has the ability to dissolve pyrite without generation of the toxic H.sub.2S. Furthermore, the new formulation is cheaper and has very low corrosion rate compare to 15 wt. % HCl with corrosion inhibitor. The disclose method uses the disclosed new formulation to dissolve iron sulphide scale, performed at about 100-150° C. and about 500-2000 psi.

Described herein are methods of treating fluid comprising hydrocarbons, water, and polymer being produced from a hydrocarbon-bearing formation are provided. The method can include 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 viscosity reducer is buffered at a pH of 7 or less (e.g., at a pH of from 2 to 7, such as at a pH of from 3.5 to 7, or at a pH of from 5 to 7). 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.

The present disclosure provides a drilling fluid lubricant and a preparation method and use thereof. The preparation method includes steps of: 1) mixing styrene and water, then adding a nano-inorganic intermediate, a crosslinking agent and an emulsifier and stirring to obtain a first mixture; 2) under an inert atmosphere, stirring the first mixture to obtain an intermediate emulsion; then heating the intermediate emulsion to 70-85° C., then adding an initiator, keeping temperature and stirring for 7-10 hours to obtain an emulsion of polystyrene nanocomposite with a particle size of 40-90 nm; the emulsion of polystyrene nanocomposite being sequentially subjected to a granulating treatment to obtain polystyrene nanocomposite particles; 3) mixing industrial base oil, polystyrene nanocomposite particles and industrial oleic acid, and stirring evenly at room temperature to obtain the drilling fluid lubricant.

A method of treating a well comprising introducing a well treatment fluid into the well, and a well treatment fluid, are provided. The well treatment fluid comprises an aqueous base fluid, sepiolite clay, and a polymer component selected from the group of an acryloylmorpholine polymer, a polyvinylpyrrolidone polymer, and mixtures thereof. In one embodiment, for example, the method is a method of drilling a well. In this embodiment, the well treatment fluid is a drilling fluid.

The present invention relates to substituted saccharides or glycosides and their use in drilling fluid compositions. The substituted saccharide or glycoside bears a substituent A, a substituent B and a substituent C, wherein the substituent A comprises in its structure a group ##STR00001##
the substituent B comprises in its structure a group ##STR00002##
and the substituent C comprises in its structure a unit —NH—R.sub.7—. The definition of each group is described in the description. The drilling fluid composition can show good temperature resistance, filtration loss reducing reduction property, pollution resistance, inhibition property, lubricating property or reservoir protection property, and has no biotoxicity.

A method of removing calcium-containing water-based filter cake from a wellbore involving contacting the calcium-containing filter cake with a biodegradable acid solution of water, hydrochloric acid, formic acid, citric acid, and a surfactant. The method is performed at a pressure of 200 to 400 psi and a temperature of 50 to 125° C. The method removes calcium-containing filter cake made of water, calcium carbonate, a polymer or starch and a clay. The method meets industry standard steel corrosion rates of less than 0.049 lb/ft.sup.2 per day. Also disclosed is a biodegradable acid solution of water, hydrochloric acid, formic acid, citric acid, and a surfactant that meets OECD 301B thresholds for ready biodegradability.

A method may include: analyzing each of a group of inorganic particles to generate data about physicochemical properties of each of the inorganic particles; and generating a correlation between a reactivity index of each of the inorganic particles and the data.

A system and method for generating base water and precipitate, including combining produced water with seawater to precipitate barium sulfate from barium in the produced water and from sulfate in the seawater, and separating the precipitate to give the base water and the precipitate. The base water may have less than a specified amount of sulfate and be utilized for hydraulic fracturing fluid. The precipitate may give a weighting agent for drilling.

A modified high density brine for use in subterranean drilling and completion operations. The modified high density brine includes the addition of high density particle addition that can optionally be surface-modified. The resultant modified high density brine eliminates the need for toxic, corrosive, and costly ZrBr.sub.2 additions or other ionic additives to boost the density of the modified high density brine to 15-17 lbs./gallon or greater.

A preparation method of a fully adaptive modified nanographene plugging type anti-collapse drilling fluid is disclosed. A modified nanographene slurry anti-collapse agent and a water-based drilling fluid containing the modified nanographene slurry anti-collapse agent are disclosed. The preparation method includes subjecting a nanographene and a mixed acid to a first contact to obtain a mixed liquid, dropwise adding potassium chlorate into the mixed liquid under the condition of ice-bath pan to carry out a modification treatment, so as to obtain a modified nanographene, and subjecting the modified nanographene to a second contact with water to prepare a modified nanographene slurry.