Influence of perlite on the stability of filter cake in low-density drilling fluids system

Enhancing drilling fluid performance in the oil and gas industry involves addressing various criteria across technical, environmental, and economic aspects. Consequently, this study encompassed several factors such as rheology, filtration, formation damage, and additives to design appropriate and cost-effective drilling fluid. The potential of perlite as an additive for low-density drilling was assessed in this work. A comprehensive laboratory experimental approach was applied to gain an in-depth understating of perlite's performance. The investigation included evaluating the rheological properties, filter cake quality, and characterizing filtration medium pore distribution. Additionally, sensitivity tests were also conducted to judge the effectiveness of perlite as a primary viscosifier and filtration agent. Through these tests, a holistic assessment of perlite's capabilities was achieved. The findings indicated that while perlite was not suitable for use as the primary viscosifier or as the main filtration agent, its use as a secondary agent exhibited a positive impact, particularly in reducing solid invasion by approximately 93%. The optimum perlite concentration was 3 lb./bbl., with good enhancements in filtration volume, filter cake thickness and porosity by 50%, 40%, and 14%, respectively. Additionally, employing a combined particle distribution approach for the calcite, rather than a singular grade, resulted in substantial improvements in the examined properties. The most notable improvement was observed in filter cake permeability, which decreased by nearly 93%. The other parameters were improved by 80% for filtration volume, 74% for filter cake thickness, and 24% for solid invasion. This work highlighted the usability of perlite in low-density mud and how it can improve the drilling fluid properties.