Drilling-fluid additives

Mud lubricants and spotting fluids, although not needed for every well, are essential for many deep directional wells. The consumption of these materials is difficult to estimate, and represents a relatively small fraction of the total drilling fluid additive market. 

The classification of drilling fluid additives is based on the definitions of the International Association of Drilling Contractors [30]. 

Thermal degradation of sulfur-containing drilling fluids additives (e.g., lignosulfates). 

As mentioned earlier, microorganisms can attack drilling fluid additives and introduce corrosive agents to the system. Therefore, it is very important to monitor their activity and detect any source of problem as early as possible. API RP 38 is probably the most widely used testing procedure in the industry [201]. The methods that can be used to monitor the microbial activity can include the following [201,208] ... 

When high temperatures above 300°F are expected, do not use sulfur-containing compounds as drilling fluid additives. In general, avoid using chemical additives that can at operating temperatures. 

A drilling fluid additive, which acts as a clay stabilizer, is the reaction product of methylglucoside and alkylene oxides such as ethylene oxide, propylene oxide, or butylene oxide. Such an additive is soluble in water at ambient conditions, but becomes insoluble at elevated down-hole temperatures [386], Because of their insolubility at elevated temperatures, these compounds concentrate at important surfaces such as the drill bit cutting surface, the borehole surface, and the surfaces of the drilled cuttings. 

M. Alonso-Debolt and M. A. Jarrett. Drilling fluid additive for water-sensitive shales and clays, and method of drilling using the same. Patent EP 668339, 1995. 

S. N. Davies, G. H. Meeten, and P. W. Way. Water based drilling fluid additive and methods of using fluids containing additives. Patent US 5652200, 1997. 

J. M. Getliff and S. G. James. The replacement of alkyl-phenol ethoxy-lates to improve the environmental acceptability of drilling fluid additives. In Proceedings Volume, volume 2, pages 713-719. 3rd SPE et al Health, Safety Environ Int Conf (New Orleans, LA, 6/9-6/12), 1996. 

A. D. Patel and H. C. McLaurine. Drilling fluid additive and method for inhibiting hydration. Patent US 5149690,1992. 

B. B. Patel. Drilling fluid additive and process therewith. Patent WO 0020527, 2000. 

R. A. Rose. Method of drilling with fluid including nut cork and drilling fluid additive. Patent US 5484028, 1996. 

M. Sano. Polypropylene glycol (PPG) used as drilling fluids additive. Sekiyu Gakkaishi, 40(6) 534-538, November 1997. 

Radenti et al. reported the corrosion rate of a typical potassium chloride fluid of 247 mils/year at 212°F. In contrast, they found by substituting potassium carbonate for potassium chloride, the corrosion rate was reduced to 3 mils/year t10 . Unfortunately, potassium carbonate is not optimum as a drilling fluid additive because it can produce massive amounts of calcium precipitation, may elevate the pH to undesirable levels, and in all cases reduces the calcium ion concentration to such a low level as to promote destabililzing cation exchange with clay minerals. 

England, A.A. and Davis, N., II "The Characterization of a Drilling Fluid Additive," IADC/SPE paper 17199, 1988 IADC/SPE Drilling Conference, Dallas, February 28-March 2. 

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