Research Papers: Petroleum Wells-Drilling/Production/Construction

Predicting Dynamic Barite Sag in Newtonian-Oil Based Drilling Fluids in Pipe

[+] Author and Article Information
Tan Nguyen

Department of Petroleum and Natural Gas Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Pl. Socorro, NM 87001tcnguyen@nmt.edu

Stefan Miska, Mengjiao Yu

Nicholas Takach

 McDougall School of Petroleum Engineering, The University of Tulsa, 800 S. Tucker Dr. Tulsa, OK 74104Nicholas-Takach@utulsa.edu

J. Energy Resour. Technol 133(2), 023102 (Jun 17, 2011) (10 pages) doi:10.1115/1.4004026 History: Received July 20, 2010; Revised April 05, 2011; Published June 17, 2011; Online June 17, 2011

Barite Sag is the settling of barite particles in the wellbore (or other weighting materials), which results in undesirable fluctuations in drilling fluid density. A variety of major drilling problems including lost circulation, well control difficulties, poor cement jobs, and stuck pipe can result from uncontrolled barite sag. Study of this phenomenon and how to mitigate its effects has long been of interest. This paper describes a fundamental mathematical approach to analyze the settling of barite particles in shear flow of Newtonian fluids. A set of four coupled partial differential equations to describe dynamic barite sag in Newtonian fluids in pipe flow is obtained by applying mass and momentum conservation for solid and liquid phase. Solid concentration in axial and radial directions as a function of time is calculated by using an explicit numerical method to solve these equations. A number of experiments in a flow loop were conducted to verify the mathematical model. Two mass flow meters were installed at the inlet and outlet of the flow loop’s test section. Differences in the density measurements over time were converted to the solid accumulation, which was compared with results from the modeling. In addition, based on the experimental results, three different stages of barite accumulation due to the settling and bed pickup of barite particles during circulation will be presented. The proposed methodology and results of this study will help drillers have a better understanding in terms of undesirable density fluctuations and barite bed characteristics.

Copyright © 2011 by American Society of Mechanical Engineers
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Figure 3

Density measurements at the inlet and outlet of the test section ρ = 9.0 PPG; θ = 90 degrees from vertical; u = 30.64 ft/min

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Figure 4

Barite bed characteristics

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Figure 1

Schematic of the Barite Sag Flow Loop (BSFL)

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Figure 2

Barite Sag Flow Loop

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Figure 5

A different interpretation of the results in Fig. 2 Barite accumulation in a unit volume of the test section

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Figure 6

Effect of average velocity on dynamic barite sag: θ = 90 degrees from vertical; ρ = 9 PPG

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Figure 7

Effect of fluid density on dynamic barite sag: θ = 90 degrees from vertical; u = 42.89 ft/min

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Figure 8

Solid concentration profile in lateral (a) and axial (b) direction as a function of time Initial solid concentration Co = 0.067; mean velocity u = 30.64 ft/min; 90 degrees from vertical

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Figure 9

The test section of the BSFL: L = 3.66 m and ID = 2

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Figure 10

Modeling results: Effect of mean velocity on barite accumulation in the test section θ = 90 degrees from vertical; ρ = 7.5 PP

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Figure 11

Comparison between modeling and experimental data: ρ = 7.5 PPG; u = 30.64 ft/min; θ = 90

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Figure 12

Comparison between modeling & experimental data: ρ = 9.0 PPG; u = 30.64 ft/min; θ = 90



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