<p>The application of managed pressure drilling technology has increased dramatically due to the ability of control gas kick in a circulating drilling condition. During the treatment of gas kick, the migration of cuttings in the wellbore is complicated by invasive gas, which may lead to the sinking of sand-stuck drill and the large error of bottom hole pressure. Accurate description of cuttings slippage in gas-liquid phase is of great significance for wellbore cleaning and the control accuracy of bottom hole pressure during MPD. In this study, the wellbore bubble flow environment was simulated by constant pressure air pump and transparent wellbore, and the settling characteristics of spherical particles under different gas volume concentration were recorded and analyzed by high-speed photography. A total of 225 tests were conducted to analyze the influence of particle diameter (1-12mm), particle density (), liquid viscosity and bubble volume concentration on particle settling velocity. Gas drag force is defined to quantitatively evaluate the bubble's resistance to particle slippage. The relationship between bubble drag coefficient and particle Reynolds number&nbsp;is obtained by fitting the experimental results. An explicit settling velocity equation is established by introducing Archimedes number. This explicit equation with average relative error of only 5.12% can directly predicts settling velocity of the sphere in bubble containing Newtonian fluids. The models for predicting bubble drag coefficient and settling velocity are valid with particle Reynolds number ranging from 0.05 to 167 and bubble volume concentration ranging from 3.0% to 20.0%. Besides, a trial-and-error procedure and an illustrative example are presented to show how to calculate bubble drag coefficient and settling velocity in bubble containing fluids. The results of this study will provide the theoretical basis for wellbore cleaning and accurate downhole pressure to further improve the performance of MPD in treating gas influx.</p><p>Keywords: Settling velocity, Bubble containing fluid, Gas drag coefficient, Newtonian fluid, &nbsp;Explicit equation.</p>

Settling Behavior of Particles in Bubble Containing Newtonian Fluids: Experimental Study and Model Development

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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