Drilling mud dispersants

Reservoir wettability modifiers Reservoir fines stabilizers Tank/vessel sludge dispersants Drilling mud dispersants... 

Additional large-volume uses of lignosulfonates include animal feed pellet binders, dispersants for gypsum board manufacture, thinners/fluid loss control agents for drilling muds, dispersants/grinding aids for cement manufacture, and in dust control applications, particularly road dust abatement. 

Nonfood Uses. Native com starch is principally used in nonfood appHcations in mining, adhesives, and paper industries. Pregelatinized starch is chemically unmodified, but it is physically modified. Pregelatinized starches are used to decrease water losses in oil-weU drilling muds, in cold water-dispersable wallpaper pastes, and in papermaking as an internal fiber adhesive. 

In the oil-weU drilling industry, the barite suspension used as drilling mud can be destabilized by the presence of soluble materials such as gypsum. Addition of barium carbonate precipitates the gypsum, inhibits coagulation, and thus permits the mud to retain the desired consistency and dispersion. 

Natural product-derived dispersants, such as tannins, lignins, and alginates, are still widely used as drilling mud thinners or in specialty applications where their low toxicity is a cmcial property, eg, in boilers producing steam for food applications. 

The classification of drilling muds is based on their fluid phase, alkalinity, dispersion, and type of chemicals used. 

Inhibited Muds—Dispersed Systems. These are water-base drilling muds that repress the hydration and dispersion of clays. There are essentially four types of inhibited muds lime muds (high pH), gypsum muds (low pH), seawater muds (unsaturated saltwater muds, low pH), and saturated saltwater muds (low pH). 

The methylene blue test can also be used to determine cation exchange capacity of clays and shales. In the test a weighed amount of clay is dispersed into water by a high-speed stirrer. Titration is carried out as for drilling muds, except that hydrogen peroxide is not added. The cation exchange capacity of clays is expressed as milliequivalents of methylene blue per 100 g of clay. 

Drilled solids include active drilled solids and inactive drilled solids. Clays and shales are considered to be active drilled solids they disperse into colloidal size readily and become detrimental to drilling by increasing the apparent viscosity and gel strength of the mud. Inactive drilled solids are sand, dolomite, limestone, etc. if they occur in colloidal size, these solids may increase plastic viscosity of the drilling mud. 

Polyethercyclicpolyols possess enhanced molecular properties and characteristics and permit the preparation of enhanced drilling fluids that inhibit the formation of gas hydrates prevent shale dispersion and reduce the swelling of the formation to enhance wellbore stability, reduce fluid loss, and reduce filter-cake thickness. Drilling muds incorporating the polyethercyclicpolyols are substitutes for oil-based muds in many applications [195-197,1906,1907]. Polyethercyclicpolyols are prepared by thermally condensing a polyol, for example, glycerol to oligomers and cyclic ethers. 

The modification of bentonite with alkylsilanes improves the dispersing properties [991]. Incorporation of phosphonate-type compounds in bentonites for drilling mud permits the blockage of free calcium ions in the form of soluble and stable complexes and the preservation or restoration of the initial fluidity of the mud [1222]. The phosphonates also have dispersing and fluidizing effects on the mud. 

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. 

Aqueous Drilling Muds Low-Molecular-Weight Dispersants... 

Drilling fluids (1-3) are often called drilling muds because of their appearance. This is due to the dispersed clays added to most... 

Sediment usually consists of finely divided solids that may be dispersed in the oil or carried in water droplets. The solids may be drilling mud or sand or scale picked up during the transport of the oil, or may consist of chlorides derived from evaporation of brine droplets in the oil. In any event, the sediment can lead to serious plugging of the equipment, corrosion due to chloride decomposition, and a lowering of residual fuel quality. 

Once discharged to the ocean, dispersion of drilling muds occurs along with several other processes, including sedimentation, adsorption, and chemical and bacterial degradation [44]. Several new concepts in low-toxicity drilling muds have been developed over the last decade, such as the synthetic-based drilling... 

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