New nanoparticle water-based drilling fluid formulation with enhanced thermal stability and inhibition capabilities in the Woodford shale

Drilling fluid design for unconventional reservoirs aims at preventing formation instability problems associated with fluid invasion, shale swelling, and cuttings dispersion. Although oil-based mud (OBM) can be used to achieve these goals, environmental and economic concerns limit its application. This experimental study evaluated the potential use of nanoparticles (NP) to improve water-based mud (WBM) inhibition capabilities and its ability to enhance the overall drilling fluid thermal stability while providing a cleaner technology to the industry. Characterization of Woodford shale was completed with X-ray diffraction, cation exchange capacity, and scanning electron microscopy, silica, and graphene NP were characterized with aqueous stability tests and zeta-potential. Selected NP were added at a low concentration (0.1 - 1 % wt.), and standard filtration (LTLP & HTHP), rheology, dispersion and swelling tests were conducted to investigate the inhibition improvements of the new NP-WBM. In addition, optimum formulation of the new NP-WBM was aged at different conditions (150⁰F, 200⁰F, 250⁰F) for thermal and rheological stability. Conventional KCL/PHPA fluid was used for comparison purposes. The NP showed a reduction of the chemical interactions between the WBM and Woodford shale samples, reducing the swelling and dispersion effects. Also, a synergistic effect was observed between NP and conventional additives indicating that NP had the capability to improve the WBM temperature resistance. Thus, offering an eco-friendly alternative with enhanced thermal and rheological stability of the overall WBM formulation and providing more efficient drilling and wellbore stability --Abstract, page iii