UBC Theses and Dissertations

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UBC Theses and Dissertations

Assessing suitability of calcium bentonite for application in oil well drilling fluid Salami, Abiola


Bentonite is a clay mineral widely used in many industrial applications. Bentonite is a major constituent of the drilling fluid used in oil well drilling operations. Some of the functions of drilling fluid include removal of drilled cuttings from the hole, cooling, and lubrication of the drill bit, and suspension of drilling cuttings when operations are stopped. There are two major forms of bentonite: sodium and calcium bentonite. Sodium bentonite is preferably used in the formulation of drilling fluid due to a high swelling potential which allows for high viscosity build up and a lower rate of filtration. However, there is a potential depletion of Wyoming sodium bentonite as a short supply of the high-quality sodium bentonite has been reported. Prior research has shown that the presence of exchangeable cation in the calcium bentonite has made it possible to upgrade its swelling capacity thereby improving the viscosity build-up and reducing the rate of filtration. In view of this, the present study investigated the suitability of calcium bentonite was treated with sodium carbonate (Na₂CO₃) and magnesium oxide (MgO) as a potential alternative to the sodium bentonite for application in the oil well drilling fluid. For experimental investigation, the calcium bentonite supplied by Pacific Bentonite Limited (PBL) was procured, and the preliminary characteristics were determined; the grade and quality were assessed through cation exchange capacity, swelling index and plasticity index tests; the specific tests such as rheology and fluid loss was also conducted to assess the suitability of the PBL calcium bentonite in drilling fluids. The results showed that the PBL calcium bentonite improved considerably and can be considered for application in drilling fluids.

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