BAKER HUGHES - Drilling Fluids Reference Manual

Oil / Synthetic Fluids
Amine Lignite
Amine lignites are prepared by reacting quats or amido amines with lignites. Variances in base
materials and reaction conditions result in a wide variety of amine lignites, which has a direct
influence on their performance and thermal stability. They perform adequately up to 350°F (177°C).
Lime
Acid gases, alkalinity, and corrosion are usually controlled with lime, Ca(OH) 2 , or quicklime, CaO, in
oil-base fluids.
CO2 + H2O →H2CO3
H2CO3 + Ca(OH)2 →CaCO3 + 2H2O
H2S + Ca(OH)2 →CaS + 2H2O
If CO 2 is present, lime additions will be needed only if an anionic emulsifier is being used. Calcium
hydroxide is needed to form the calcium soap. Once the soap is formed, any introduction of CO 2 in
the fluid will not affect the fatty acid and lime reaction.
If H 2 S is introduced to the system, the CaS compound will remain stable as long as there is excess
lime present. Basic zinc carbonate can also be used to react with H 2 S.
Emulsion based drilling fluids
CARBO-DRILL ® Oil-Base Drilling Fluid System
The CARBO-DRILL ® oil-base fluid systems are designed for maximum stability and versatility.
Three systems make up the CARBO-DRILL system family – CARBO-FAST SM , CARBO-TEC ® , and
CARBO-CORE ® (see Chapter 6, Reservoir Application Fluids). Formulations for the
CARBO-DRILL system are referenced in Table 5-6 through Table 5-13 at the end of this chapter.
CARBO-DRILL systems can be formulated with low-aromatic mineral oil instead of diesel oil as the
external phase for drilling in environmentally-sensitive areas. Mineral oil systems are identified by
the S.E.A. designation (i.e., CARBO-TEC ® S.E.A., CARBO-FAST SM S.E.A., and CARBO-CORE
S.E.A). Typically, S.E.A. systems will require more organophilic clay and emulsifiers and will exhibit
lower electrical stability (ES) values when compared to diesel systems. The CARBO-DRILL systems
are very versatile, from relaxed to a very high-temperature stable system. CARBO-TEC S.E.A. is
designed specifically to meet environmental requirements for drilling in the North Sea.
CARBO-FAST SM / CARBO-TEC ®
The CARBO-FAST system is prepared as a “relaxed” oil-loss fluid with a low colloid content, and is
designed for rapid rates of penetration. Filtrate loss can be controlled over a wide range depending on
the control required for a given well.
CARBO-FAST systems can be converted to a CARBO-TEC controlled filtrate loss when low values
are required. This is achieved by using the additional products CARBO-TEC, an anionic emulsifier,
and CARBO-TROL, an asphaltic filtrate loss control additive. CARBO-TROL A-9, a non-asphaltic
filtrate loss control additive, can be substituted if desired.
The CARBO-DRILL systems can incorporate a much higher percentage of water, compared to
conventional oil-base drilling fluid. Depending on fluid weight and CaCl 2 content, the CARBO-
DRILL oil/water ratio can be used to the 45/55 - 60/40 range. Increased water content decreases the
amount of oil on cuttings as they are discharged over the shaker, allowing oil-base drilling fluids to
Baker Hughes Drilling Fluids
Reference Manual
5-26 Revised 2006