Environmental control of drilling mud discharge through dewatering in cold weather climates: Effect of ambient temperature

Document Type

Article

Publication Date

1-1-1998

Abstract

This paper presents results of an experimental study into the effect of drilling mud temperature upon dewatering performance. Three temperature ranges were considered: from flowline temperature to room temperature, from room temperature to freezing point, and the freeze -20° C (-4° F) thaw 12° C (54° F) cycle. The tested drilling fluids included unweighted and weighted fresh water muds and a weighted salt water mud. A sealed laboratory batch reactor was used in the experiments to prevent rapid vapourization of separated water at temperatures above 60° C (140°F). Also, ice or ice-salt baths were utilized for deep freezing. The dewaterability (net water removal) was measured with a bench-top plate press under constant expression pressure 207 kPa (30 psi). The freeze/thaw treatment greatly enhanced dewaterability by releasing 34 - 39% by volume of the mud water. Mechanical dewatering followed; it required half the chemicals and released an additional 36-43% of water. The process proved to be very effective, reducing waste mud volume by 64 - 72%. It is well-suited for the Arctic with its natural freeze/thaw cycles. The results of experiments at temperatures above 21° C (70°F) showed that there is little advantage to dewatering hot drilling mud diverted from active system. A 10% increase of water removal was observed above 60° C (140°F). The experiments at temperatures below 21° C (70°F) showed that in cold weather climates the waste drilling mud diverted from active system should be dewatered when its temperature is still above 40°F. Otherwise, more chemicals will be needed for separation enhancement or the dewatering process will become entirely ineffective.

Publication Source (Journal or Book title)

Journal of Canadian Petroleum Technology

First Page

35

Last Page

40

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