Table 6: Contaminated mud treated with caustic soda and lime.

Drilling Fluid Properties (unit) Before Contamination After 20%v Contamination After treatment by lime and caustic to adjust the pH between 10.5-11.5
P.V (m.Pa.s) 45 59 62
A.V (m.Pa.s) 70 125 128
Y.P (Pa) 44 8.5 22
Gel strength 10'(Pa) 10 23 12
Gel strength 10”(Pa) 17 29 20
Ca2++(mg/lit) 200 4400 6800
Mg2++(mg/lit) 10 1500 150
Total hardness (mg/lit) 210 5900 6950
Fluid loss(ml) 0 18 8
Cake thickness (mm) 3.5 20 9
Pf (ml of acid) 0.5 0 1
Mf (ml of acid) 1 0.4 1.5
HCO3- (mg) 0 488 42
CO3- (mg) 600 0 255
pH 10.5 6.7 11.5

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