Drilling fluids composition

Drilling Fluids Composition and Applications Water-Base Mud Systems Bentonite Mud... 

An oil-based drilling mud can be viscosified with maleated ethylene-propylene elastomers [919]. The elastomers are ethylene-propylene copolymers or ethylene-propylene-diene terpolymers. The maleated elastomers are far more effective oil mud viscosifiers than the organophilic clays used. On the other hand, specific organophilic clays can provide a drilling fluid composition less sensitive to high temperatures [491]. 

Scleroglucan is a polysaccharide secreted by the mycelia of certain microorganisms. It is produced by aerobic fermentation of D-glucose by such microorganisms. Scleroglucan has been proposed as a better alternative to xanthan gum for drilling fluid compositions [666]. 

HSL, 2000. Drilling Fluids Composition and use within the UK Offshore Drilling Industry. Health Safety Laboratory. 

Drilling fluids are classified as to the nature of the continuous phase gas, water, oil, or synthetic. Within each classification are divisions based on composition or chemistry of the fluid or the dispersed phase. 

Water-Based Muds. About 85% of all drilling fluids are water-based systems. The types depend on the composition of the water phase (pH, ionic content, etc), viscosity builders (clays or polymers), and rheological control agents (deflocculants or dispersants (qv)). 

Mixtures containing sulfated castor oil were used to increase the lubricity of water base drilling fluids (123). Sulfated castor oil is also used in dishwashing compounds as a hand softener. A typical cleaning composition contains sodium dodecylben2ene sulfonate, sulfated castor oil, ethanol, and water. A sulfated derivative of castor oil is used as a dispersant for plaster of Paris, reducing the water needed to form a plastic slurry (124). Pesticide emulsions can be stabilized using ethoxylated castor oil (125). 

Testing of Drilling Fluids 652. Composition and Applications 664. Oil-Based Mud Systems 675. Environmental Aspects 682. Typical Calculations in Mud Engineering 687. Solids Control 691. Mud-Related Hole Problems 695. Completion and Workover Fluids 701. 

Foam Systems. The preparation, composition, and maintenance of foam completion and workover fluids is similar to that of foam drilling fluids. The advantage of foam is the combination of low density and high lifting capacity at moderate flow rates. The use of foam as a completion fluid can be justified by. 

Neutralized sulfonated asphalt (i.e., salts of sulfonated asphalt and their blends with materials such as Gilsonite, blown asphalt, lignite, and mixtures of the latter compounds) are commonly used as additives in drilling fluids. These additives, however, cause some foaming in water or water-based fluids. Furthermore, these additives are only partially soluble in the fluids. Therefore, liquid additives have been developed to overcome some of the problems associated with the use of dry additives. On the other hand, with liquid compositions containing polyglycols, stability problems can arise. Stable compositions can be obtained by special methods of preparation [1407]. In particular first the viscosifier is mixed with water, then the polyglycol, and finally the sulfonated asphalt is added. 

A composition containing polyanionic cellulose and a synthetic polymer of sulfonate has been tested for reducing the fluid loss and for the thermal stabilization of a water-based drilling fluid for extended periods at deep well drilling temperatures [812]. 

The fluid loss control of aqueous, clay-based drilling mud compositions is enhanced by the addition of a hydrolyzed copolymer of acrylamide and an N-vinylamide [402], The copolymer, which is effective over a broad range of molecular weights, contains at least 5 mole-percent of the N-vinylamide units, which are hydrolyzed to N-vinylamine units. The copolymers can be made from various ratios of N-vinylamide and acrylamide by using common radical-initiated chain growth polymerization techniques. 

An alkoxylated fatty oil is used in a nonionic composition [1821]. The alkoxylated fatty oil has low solubility in the main emulsion phase. The process is used for breaking emulsions used in wellbore drilling fluids and in oil recovery. 

R. Carpenter and D. Johnson. Method and cement-drilling fluid cement composition for cementing a wellbore. Patent WO 9748655, 1997. 

E. Davidson. Method and composition for scavenging sulphide in drilling fluids. Patent WO 0109039A, 2001. 

D. M. Giddings and C. D. Williamson. Terpolymer composition for aqueous drilling fluids. Patent US 4678591, 1987. 

D. T. Terry, D. D. Onan, P. L. Totten, andB. J. King. Converting drilling fluids to cementitious compositions. Patent US 5295543,1994. 

J. Weaver, K. M. Ravi, L. S. Eoff, R. Gdanski, and J. M. Wilson. Drilling fluid and filter cake removal methods and compositions. Patent US 5501276, 1996. 

In situ NMR measurements can be made in conjunction with down-hole fluid sampling [5, 6]. The NMR relaxation time and diffusivity can be measured under high-temperature, high-pressure reservoir conditions without loss of dissolved gases due to pressure depletion. In cases when the fluids may be contaminated by invasion of the filtrate from oil-based drilling fluids, the NMR analysis can determine when the fluid composition is approaching that of the formation [5, 6]. 

Brine composition and polymer type should be considered together, and could lead to improved control of the viscosity of polysaccharide based drilling fluids. 

Gray, G.R., Darley, H.C.H., Rogers, W.F. "Compositions and Properties of Oil Well Drilling Fluids" 4th Ed, Gulf Publishing Houston, TX 1980. 

Barium hydroxide is used to produce barium soaps which are additives for high temperature lubricants. Other chemical applications include refining of vegetable oils vulcanization of synthetic rubber in drilling fluids in corrosion inhibitors as an ingredient in sealing compositions in plastics stabilizers for softening water and to prepare other alkalies. 

Geothermal reservoir rocks are typically fractured and therefore exhibit variable and anisotropic permeability. For that reason it is neither possible to predict with confidence how an injection well may perform with respect to its injectivity nor with respect to which way the injected fluid will flow once it is in the reservoir. Because of this complication, the success of injection varies between fields and it is anticipated that a special injection scheme must be developed for each field depending on its characteristics, mainly the three-dimensional distribution of permeability and the waste fluid composition. Injection may require drilling of special wells. Alternatively, wells drilled for the purpose of production may not have adequate yield but can be used successfully as injection wells. When this is the case, no special wells need to be drilled for injection purposes, which reduces road building and therefore scenery spoliation. 

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