BAKER HUGHES - Drilling Fluids Reference Manual

RESERVOIR APPLICATION FLUIDS
220
Effect of CLEAR-DRILL Salts on Thermal Stability of Xanthan
Polymers
200
Transition Temperature (°C)
180
160
140
120
CLEAR-DRILL N
CLEAR-DRILL K
100
0 10 20 30 40 50 60 70 80
Salt Concentration (% w/w)
Figure 6 - 12
Effect of CLEAR-DRILL Salts on Thermal Stability of Xanthan
Polymers
Further investigation revealed that formates are compatible with all commonly used drilling fluid
polymers. Sodium and potassium formates are readily available and the use of these products on
their own, or in combination, can provide brines with densities up to approximately 1.58 S.G. (13.2
ppg).
A further advantage of formates is that they will not react with any cations to produce insoluble
salts, thus minimizing the possibility of producing precipitates downhole upon contact with
formation water. In particular, all the divalent metal formates are readily soluble in water.
Additionally, the toxicity of formates is generally very low, both to mammalian and aquatic
species, thus enabling environmentally benign fluids to be formulated for use in sensitive areas.
The complete absence of chlorides from the system allows easy disposal of waste fluid into fresh
water systems, a significant benefit when drilling on land.
Description of System Components
CLEAR-DRILL ® N
CLEAR-DRILL N (sodium formate) is a crystalline white powder, highly soluble in water, giving
mildly alkaline brines up to a density of 1.35 S.G. (11.2 ppg). The product can also be supplied as a
concentrated brine.
• System applicability: CLEAR-DRILL N
• Temperature limitations: Stable at 250°C (482°F)
CLEAR-DRILL ® K
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 6-31