Customized High-Performance, Water-Based Mud for Unconventional Reservoir Drilling

Abstract

Non-aqueous fluid (NAF) is a suitable choice over water-based mud to drill unconventional reservoirs. NAF can provide advantages such as shale stability, lubricity and wider mud density range, despite of cost, logistics, loss intolerance and environmental friendliness. Further, requirement for specialized high-resolution real-time borehole imaging in unconventional drilling makes NAFs inapplicable because of logging-tool-fluid compatibility issues. These challenges initiated the operator to design a fit-ofpurpose high-performance water-based drilling fluid (HPWBM) system for unconventional reservoirs.This customized system is specially formulated to drill long sections in unconventional reservoirs with the required wellbore stability across sensitive zones, and compatible in delivering high-resolution imaging tools, lubricous to reduce friction coefficient along extended lateral section and environmentally compliant due to low salinity nature. The customized high-performance water-based drilling fluid system consistently matches or outperforms oil-based mud systems.The paper presents a detailed mineralogy study on various core and cutting samples. Fluid was designed based on the mineral composition of cores and cutting samples to achieve good shale stability, particle plugging, swelling and cutting integrity with stable rheology. Pore pressure transmission was also considered on these core samples to control clay hydration and swelling to prevent breakout and sloughing thus minimizing formation destabilization. Nano-size based materials were also used to control shale, penetrate and seals micro fractures to avoid fluid invasion into the wellbore.The detailed study and design's purpose is to formulate a customized high-performance water-based drilling fluid system for the unconventional applications in Saudi Arabia for drilling horizontal, deviated, and extended-reach wells, trouble-free whilst delivering high-definition image logs for efficient fracture placement.

Research progress and development tendency of polymer drilling fluid technology for unconventional gas drilling

“…PERFORMAX owns outstanding inhibition by the combined use of polyalcohol and an aluminum-based polymer. Subsequently, Baker Hughes introduced nanotechnology and developed the LATIDRILL system which is the first report of the commercialized application of nanotechnology in the waterbased drilling fluid (Bakerhughes Media Center, 2012; Riley et al, 2012;Witthayapanyanon et al, 2013;Yadav et al, 2015). The application result in Cameroon Sea shows that LATIDRILL could improve wellbore stability, prevent bitballing, decrease friction, and elevate the ROP to a great extent.…”