Particle settling in non-Newtonian drilling fluids
Doctoral thesis
Permanent lenke
http://hdl.handle.net/11250/183688Utgivelsesdato
2009-12-14Metadata
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- PhD theses (TN-IPT) [21]
Originalversjon
Particle settling in non-Newtonian drilling fluids / by Tor Henry Omland, Stavanger : University of Stavanger, Faculty of Science and Technology, Department of Petroleum Engineering 2009 (PhD thesis UiS, no. 80)Sammendrag
Particle settling is relevant for several aspects of drilling and completion operations,
and is directly related to safety and operational efficiency. The primary
function of particles added to drilling fluids is to provide density stabilizing the
wellbore and hinder influx of fluids and gas, causing a kick situation. Keeping
the particles suspended in the fluids is also critical to avoid problems such
as stuck down hole equipment, poor cementing of casings, lost circulation and
avoid formation damage.
The main objective of the present work is to improve the understanding of
particle settling in non-Newtonian drilling fluids. The work focuses on identifying
parameters critical for particle settling which are directly relevant for
everyday handling and use of drilling and completion fluids. To identify these
parameters, laboratory techniques have been developed that allow continuous
monitoring of the particle settling process in a fluid. The majority of the parameters
identified have previously not been studied by the oil industry. This
includes parameters such as the composition of the internal brine phase of oil
based drilling fluids, added shear energy during preparation of these and the
effect of particle morphology on settling. Operational parameters, such as vibrations
during drilling, and the efficiency of solids removal equipment have also
been discovered to have significant impact on the particle settling rate.
Throughout this work the complexity of particle settling in the fluids has
clearly been demonstrated. Conventional settling models have shown not to
predict the effect of this phenomena accurately. The complexity of the sag phenomena
requires the development of significantly improved practical equipment
to optimize and monitor the sag stability of drilling fluids at the rig site.
Beskrivelse
PhD thesis in Petroleum engineering