Emulsifiers, drilling fluids

Surfactants. Surfactants (qv) perform a variety of functions in a drilling fluid. Depending on the type of fluid, a surfactant may be added to emulsify oil in water (o/w) or water in a nonaqueous Hquid (w/o), to water-wet mud soHds or to maintain the soHds in a nonwater-wet state, to defoam muds, or to act as a foaming agent. 

Emulsions. Emulsions are formed when one liquid is dispersed as small droplets in another liquid with which the dispersed liquid is immiscible. Mutually immiscible fluids, such as water and oil, can be emulsified by stirring. The suspending liquid is called the continuous phase, and the droplets are called the dispersed (or discontinuous) phase. There are two types of emulsions used in drilling fluids oil-in-water emulsions that have water as the continuous phase and oil as the dispersed phase, and water-in-oil emulsions that have oil as the continuous phase and water as the dispersed phase (invert emulsions). 

Uintaite is not easily water wet with most surfactants. Thus, stable dispersions of uintaite are often difficult to achieve, particularly in the presence of salts, calcium, solids and other drilling fluid contaminants and/or in the presence of diesel oil. The uintaite must be readily dispersible and must remain water wet otherwise it will coalesce and be separated from the drilling fluid, along with cuttings at the shale shaker or in the circulating pits. Surfactants and emulsifiers are often used with uintaite drilling mud additives. 

A liquid oil, an emulsifier, and a friction modifier, which includes certain polyether compounds, can be added to a drilling fluid consisting of a water-in-oil emulsion formed from a brine [1155]. The friction modifier serves to decrease the coefficient of friction of the well drilling fluid. Decreasing the coefficient of friction lowers the force required to turn the drill bit in the hole. Gravitational forces increase the coefficient of friction in deviated-, horizontal-, and extended-reach wells. 

Emulsifiers have been used to prepare oil-external emulsion drilling fluids. Surfactants used as emulsifiers include fatty acid salts, fatty acid amides, petroleum sulfonates, and lignosulfo-nates. 

Use In foods as stabilizer, thickener, emulsifier, and packaging material cosmetics sizing and finishes for textiles pharmaceuticals paints, bonding agent in paper manufacture drilling fluids. 

AquamuL [Aquaness] Modified fatqr acids oil-sol. emulsifiers fw drilling fluids. 

Duomac . [Akzo Akzo Chem. BV] Alkyl propanediamine diacetates emulsifier, corrosion inhibitex, flotation reagent bactericide for drilling fluids, pigment flushing, flocculation. 

Witcomul. [Witco/Organics] Esters emulsifier, thickener, emulsion stabilizer ftx industrial q>piics., drilling fluid additive for petroleum industty. 

The water-in-oil or invert emulsion oil-based drilling fluids provide much of the required rheological and fluid loss properties. The emulsion is stabilized by the use of emulsifiers that prevent the coalescence of the droplets and formation of separated phases (56, 57). Figure 5 shows the chemical structure of the two emulsifiers that are commonly used... 

Figure 5. Common emulsifiers used in invert emulsion oil-based drilling fluids.

Invert emulsion drilling fluids are commonly selected for their temperature stability and their ability to prevent the wellbore stability problems associated with the hydration of clays in shale formations. The thermodynamic activity aw of the water in the aqueous (dispersed) phase is controlled by the addition of a salt (usually calcium chloride) to ensure that it is equal to or less than the activity of the water in the drilled shale formations. The emulsified layer around the water droplets is claimed to act as a semipermeable membrane that allows the transport of water into and out of the shale but not the transport of ions (61). When the activities (or, more strictly, the chemical potentials) of the water in the shale and invert emulsion are equal, then no net transport of water into or out of the shale occurs (i.e., the drilling fluid does not hydrate or dehydrate the shale). This equality of water activity has lead to the development of so-called balanced activity oil-based drilling fluids. 

The approach outlined previously is also applicable to the aqueous phase in an invert emulsion oil-based drilling fluid. The chemical potential of the water in the aqueous (dispersed) phase is usually controlled by the concentration of calcium chloride. The transport of water between the shale and the aqueous phase of the invert emulsion is less complex than with water-based drilling fluids, because with the emulsions there is no cation exchange between the ions in the fluid and in the shale. The thin emulsified layer surrounding the water droplets is postulated to act as a semipermeable membrane that allows only the passage of water (61). 

The metals may be present in oils as inorganic particulate matter (such as mineral grains or absorbed on clay minerals), in emulsified formation waters, introduced as drilling fluids or corrosion inhibitors or present as organometallic complexes. Only if the metals are present in an oil-soluble form as true complexes can meaningful geochemical information be obtained from trace element data. 

Uses Surfactant for cosmetics, feed, foods, textiles, leather, pharmaceuticals, paints/coatings, lubricants, emulsion polymerization, silicon and wax emulsions, metal treatment, and plastics antistat emulsiFier for foods, feed coemulsiFier lubricant, softenerfor textiles and fibers process defoamer opacifier solubilizer dispersant suspending agent coupling agent drier for paints thickener emulsion stabilizer drilling fluid additive lubricant, rust inhibitor, penetrant in metalworking Features Lipophilic Mam JDistrib. DelCon Lonza Trade Names Kosteran-T/1 Lonzest TAG... 

Formula C3H702(0CHCH3CH2)x(0CH2CH2)y0H, avg. X = 66, avg. y = 12 Properties Nonionic Toxicology TSCA listed Uses Emulsifier, solvent in cosmetics defoamer for cutting and drilling fluids, fermentation, chem. mfg., acid gas treatment, pulp and paper, and textiles Features Provides low odor, low irritation, low toxicity to personal care prods Manuf./Distrib. Aldrich http //www.sigma-aldrich.com... 

Lipid surfactants are used as emulsifiers, texturizing agents, lubricants and plasticizers in pharmaceuticals, cosmetics, textiles, extended plastics and oil drilling fluids etc. 

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