Comparison of Performance of Standard Water-based and Oil-based Mud For Drilling Purpose During Carbon Dioxide Gas Kick From Adjacent Reservoir

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Author(s) Adebayo, Thomas Ayotunde
Pages 729-731
Volume 2
Issue 5
Date May, 2012
Keywords Oil-based mud, water-based mud, CO2 contamination, CO2 kick in mud

Abstract

This experimental study compares the effect of carbon dioxide, CO2, leakage from adjacent storage reservoir on drilling mud being used in a nearby reservoir. Comparison of the effect of CO2 on Water-based and Oil-based drilling fluids will help in the selection of best drilling fluid for the nearby reservoir. It was observed that the percentage change in the density of both mud after contamination with CO2 were negligible. Though, there was about 7% increase in oil-based mud density at the end of 25days with a corresponding 17% decrease in water-based mud density within same period but this is negligible as the same mud cannot be used to drill for up to 25days without weighting the mud for deeper depth. Unlike density, there was sharp increase of 242% in viscosity of oil-based mud with a corresponding 35.8% reduction in the viscosity of the water-based mud within the first 3 days of contamination with CO2. The conclusion is that water-based mud is more stable than oil-based mud when there is serious CO2 gas kick but a standard mud of midway properties, oil-in-water emulsion, may be ideal as a cheap mud for this purpose. Further study is expected to be carried out on suitable additive that could enhance the properties of the two muds and also on the suitability of the use of oil-in-water drilling mud or synthetic mud for CO2 contaminated environment.

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