US 5,629,270 AGranted

Thermally stable oil-base drilling fluid

AssigneeUnion Oil Company of California

InventorDonald C. Van Slyke

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Abstract

Oil-base drilling fluids containing a non-sulfonated polymer and/or a non-organophilic clay maintain desirable rheological properties at elevated temperatures.

Claims8

Dependent claims

An oil-base drilling fluid having a density of about 0.9 kg/l (7.5 pounds per gallon (ppg)) to about 2.4 kg/l (20 ppg) and comprising:

(a) an oil,
(b) a weighting agent,
(c) a surfactant,
(d) a non-organophilic clay,
(e) a non-sulfonated polystyrene;
and
(f) less than about 0.143 g/m.sup.3 (0.05 pounds per barrel (ppb)) sulfonated polymer.

4 more elements

Dependencies are inferred from the claim text.

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Abstract

Oil-base drilling fluids containing a non-sulfonated polymer and/or a non-organophilic clay maintain desirable rheological properties at elevated temperatures.