A wellbore treatment fluid comprising: a base fluid; and a water-soluble salt, the salt comprising: a cation; and an anion, wherein the anion is selected from phosphotungstate, silicotungstate, phosphomolybdate, and silicomolybdate. The treatment fluid can have a density greater than or equal to 13 pounds per gallon. A method of treating a portion of a subterranean formation penetrated by a well comprising: introducing the treatment fluid into the well.

A wellbore treatment fluid comprising: a base fluid; and a water-soluble salt, the salt comprising: a cation; and an anion, wherein the anion is selected from phosphotungstate, silicotungstate, phosphomolybdate, and silicomolybdate. The treatment fluid can have a density greater than or equal to 13 pounds per gallon. A method of treating a portion of a subterranean formation penetrated by a well comprising: introducing the treatment fluid into the well.

Methods and apparatuses that measure thermal conductivity and electrical conductivity of a emulsified drilling fluid may be used to indirectly measure the salinity and the average specific gravity of the solids in the emulsified drilling fluid. For example, a drilling assembly may comprise a drill string extending into a wellbore penetrating a subterranean formation; a pump configured to circulate a drilling fluid through the drilling assembly; a first flow line fluidly coupling the wellbore to a retention pit; a second flow line fluidly coupling the retention pit to the pump; a third flow line fluidly coupling the pump to the drill string; and an in-line analysis system fluidly coupled to the retention pit, fluidly coupled to the second flow line, or fluidly coupled to the third flow line, the in-line analysis system comprising a thermal conductivity meter and/or an electrical conductivity meter to a sample container.

Methods and apparatuses that measure thermal conductivity and electrical conductivity of a emulsified drilling fluid may be used to indirectly measure the salinity and the average specific gravity of the solids in the emulsified drilling fluid. For example, a drilling assembly may comprise a drill string extending into a wellbore penetrating a subterranean formation; a pump configured to circulate a drilling fluid through the drilling assembly; a first flow line fluidly coupling the wellbore to a retention pit; a second flow line fluidly coupling the retention pit to the pump; a third flow line fluidly coupling the pump to the drill string; and an in-line analysis system fluidly coupled to the retention pit, fluidly coupled to the second flow line, or fluidly coupled to the third flow line, the in-line analysis system comprising a thermal conductivity meter and/or an electrical conductivity meter to a sample container.

Disclosed is a method for treating a system, the method comprising providing a composition comprising HCl, urea, complex substituted keto-amine-hydrochloride, at least one alcohol selected from the group consisting of isopropyl alcohol and propargyl alcohol, an ethoxylate, and at least one ketone selected from the group consisting of methyl vinyl ketone, acetone, and acetophenone; and inserting the composition into at least one of an oil well and a gas well.

The invention is a fluid having a kinematic viscosity from 3 to 6 mm.sup.2/s, a flash point of higher than 120? C. and a pour point lower than ?40? C., having a boiling point in the range of from 200? C. to 400? C. and a boiling range below 80? C., said fluid comprising more than 95% isoparaffins and less than 3% of naphthens by weight, a biocarbon content of at least 95% by weight, containing less than 100 ppm aromatics by weight. The invention is also a drilling fluid and the use of the fluid to improve the viscosity of the drilling fluid.

The invention is a fluid having a kinematic viscosity from 3 to 6 mm.sup.2/s, a flash point of higher than 120? C. and a pour point lower than ?40? C., having a boiling point in the range of from 200? C. to 400? C. and a boiling range below 80? C., said fluid comprising more than 95% isoparaffins and less than 3% of naphthens by weight, a biocarbon content of at least 95% by weight, containing less than 100 ppm aromatics by weight. The invention is also a drilling fluid and the use of the fluid to improve the viscosity of the drilling fluid.

Methods and apparatuses that measure thermal conductivity and electrical conductivity of a emulsified drilling fluid may be used to indirectly measure the salinity and the average specific gravity of the solids in the emulsified drilling fluid. For example, a drilling assembly may comprise a drill string extending into a wellbore penetrating a subterranean formation; a pump configured to circulate a drilling fluid through the drilling assembly; a first flow line fluidly coupling the wellbore to a retention pit; a second flow line fluidly coupling the retention pit to the pump; a third flow line fluidly coupling the pump to the drill string; and an in-line analysis system fluidly coupled to the retention pit, fluidly coupled to the second flow line, or fluidly coupled to the third flow line, the in-line analysis system comprising a thermal conductivity meter and/or an electrical conductivity meter to a sample container.

Methods and apparatuses that measure thermal conductivity and electrical conductivity of a emulsified drilling fluid may be used to indirectly measure the salinity and the average specific gravity of the solids in the emulsified drilling fluid. For example, a drilling assembly may comprise a drill string extending into a wellbore penetrating a subterranean formation; a pump configured to circulate a drilling fluid through the drilling assembly; a first flow line fluidly coupling the wellbore to a retention pit; a second flow line fluidly coupling the retention pit to the pump; a third flow line fluidly coupling the pump to the drill string; and an in-line analysis system fluidly coupled to the retention pit, fluidly coupled to the second flow line, or fluidly coupled to the third flow line, the in-line analysis system comprising a thermal conductivity meter and/or an electrical conductivity meter to a sample container.

Treatment fluids containing salts, surfactants, mutual solvents and fibers may be used to remove wellbore filter cakes that have been deposited by drilling fluids. The drilling fluids may be water-base, oil-base, synthetic-base or emulsions. The fibers may be selected from polylactic acid, celluloses, polyesters, polyvinyl alcohols and polyethylene terephthalates. A combination of straight and crimped fibers is present in the treatment fluid.