000			02136nab a2200205 4500
005			20260523194444.0
008			260224s2011 xxu
100	1		_aNguyen, Tan _952146
100	1		_aMiska, Stefan _916890
100	1		_aYu, Mangjiao _952147
245	0	0	_aExperimental study of dynamic barite sag in oil-based drilling fluids using a modified rotational viscometer and a flow loop
260			_cjul. 2011
270			_a18/11/2011 ; 18/11/2011
300			_a6 p. ; 160-165
520			_aTranscripción del resumen del autor. During drilling operations, control of the sub-surface pressure is of utmost importance. High density minerals, such as barite and hematite, are used to increase the density of drilling fluids and thereby control these pressures. However, contributing factors, such as the gravitational force, cause the weighting material particles to settle out of the suspension. This is designated as "sag" within the drilling industry and can lead to a variety of major drilling problems, including lost circulation, well control difficulties, poor cement jobs, and stuck pipes. The study of this phenomenon, including ways to mitigate its effects, has long been of interest. In this paper several methods for evaluating dynamic barite sag in oil-based drilling fluids are examined in a flow loop with the use of a rotational viscometer modified by the addition of a sag shoe (MRV). Tests using the MRV in the range of 0-100 RPM were conducted, and the effects of rotation speed on sag were correlated with flow loop tests performed by varying the inner pipe rotation speed. The combined effects of eccentricity and pipe rotation on dynamic barite sag in oil-based drilling fluids are also described in this paper. Flow loop test results indicate that pipe rotation has a greater impact on reducing sag when the pipe is eccentric rather than concentric. Additionally, results in the MRV indicate a strong correlation between the test RPM and the degree of measured sag
581			_a1
773	0		_tJournal of Petroleum Science & Engineering _g78
942			_cARTICULO _2ddc
999			_c186577 _d186577