LAUSR

Abstract The drilling fluid is the primary barrier element against a kick. In the path of drilling fluids evolution, synthetic-based drilling fluid (SBDF) is commonly used on offshore rigs due to its benefits to the high level of drilling complexity, especially at deep and ultra-deep-water scenarios. However, when formation gas dissolves in the mud due to high pressure and high temperature, the complexity of kick detection increases significantly. Furthermore, environmental concerns raised a red flag on SBDF usage due to potential impacts on the marine environment, with most governmental agencies around the world passing very strict regulations. Considering both aspects - safety, and environmental concerns - glycerin emerges as a potential candidate to perform a key role as a base drilling fluid (GBDF). At first, a GBDF has the potential to behave as an SBDF due to its benefits, such as lubricity and shale stabilization, and, at the same time, it has the same characteristics of water-based drilling fluid (WBDF) with very low methane solubility, the major component of natural gas. Additionally, GBDF is considered to be more environmentally friendly than SBDF. In this work, we first analyzed the PVT properties and rheology of three different molar composition glycerin-based drilling fluids: 100% glycerin, 50-50% glycerin/brine, and 40–60% glycerin/brine. Then, we performed the PVT properties analysis of methane (10–50% molar mass) mixed with each of these GBDF mentioned. In a systematic constant composition expansion through a visual high-resolution PVT cell under temperature and pressure range conditions of 20–80 °C and 0–55 MPa, respectively, and rheology characterization. The GBDF exhibited interesting results for density and rheology parameters similar to an SDBF and no methane solubility. Finally, mathematical correlations are proposed and applied to illustrate a pit-gain calculation comparing to an n-paraffin-based drilling fluid.