Novel, Solids-Free, Oil-Based Drill-In Fluid Additive for High-Density Applications

Abstract

Reservoir Drill-In Fluids-(RDF's) minimize damage in Open-Hole completions from mud filtrate and the invasion of the near-well bore by insoluble solids. Solids are well-known to pose an undesirable risk to the completion process and the reservoir itself. This paper presents the development of a novel, oil-based additive for RDF's that provides density up to 16.5 PPG equivalent, with no solids in its neat form. As industry has begun to develop deeper, hotter wells, the need for fluids up to and including 16.5 PPG has increased. These fluids are generally purpose-designed for individual wells, after extensive testing and qualification to optimize non-damaging properties, while meeting drilling and completion criteria. These fluids commonly take two forms: (1) water-based, and (2) oil-external emulsion, based on reservoir properties, drilling difficulty, and environmental concerns. Historically, the low specific gravity of the base oils used in oil-based RDF's puts them at a disadvantage in meeting density targets above 13 PPG, while also maintaining drilling properties. Using novel chemistry to address this problem, we executed an extensive amount of formulation, testing, and evaluation of candidate molecules to address the need for a liquid weighting agent. The results from this development process include rheological, high-pressure high-temperature (HPHT) fluid loss, and other performance data. This novel chemistry has the potential to make a significant contribution to drilling performance and completion integrity, by delivering solids-free density to RDF formulations above 13 PPG.