Nanoparticle Fluid Loss Control Additive Enables Zero-Spurt Loss in High Performance Water-Based Drilling Fluids

Abstract Fluid invasion into permeable formations can lead to a host of undesirable effects during well construction. These effects which include formation instability, formation damage, and differential sticking, can result in reduced wellbore productivity or increased non-productive time (NPT). These issues are particularly acute in water-based drilling fluids which tend to have worse fluid loss control than non-aqueous fluids. A variety of additives, including clay minerals and polymers, have been used extensively to mitigate fluid loss in water-based fluids. Often additional materials, such as latex polymer dispersions, are added to act as sealing agents to further reduce fluid loss. The primary role of these sealing agents is to reduce spurt loss, which is the fluid lost prior to the construction of an adequate filter cake and establishment of steady-state fluid loss behavior. Despite application of these combinations of products, there remains a need for improved offerings particularly at higher temperatures and in more permeable formations. In this paper, we report a new hybrid organic/inorganic nanoparticle fluid loss control additive that substantially reduces fluid loss volumes and remarkably affords fluids with no spurt loss. The new hybrid nanoparticle additive was evaluated in several concentrations in a variety of water-based drilling fluid formulations, including both freshwater and brine-based fluids. Standard rheological properties were measured using a rotational viscometer, both before and after aging at elevated temperature. The critical fluid loss measurements were conducted using both high temperature/high pressure (HTHP) filtration and particle plugging tests (PPT). For PPT, various pore throat sizes and differential pressures were evaluated. These results were compared to parallel trials conducted with the same water-based mud formulations containing alternative fluid loss or sealing agents. Water-based drilling fluids containing the new nanoparticle were shown to outperform conventional additives. In some formulations filtrate volumes in both PPT and HTHP tests were reduced significantly. In others, a considerably lower loading of the nanoparticle additive yielded filtrate volumes that were comparable to higher loadings of existing additives. In both cases the rheological impact of the nanoparticle was not substantially different than the alternatives evaluated. The nanoparticle solution was shown to be robust, providing fluid and spurt loss reduction across a range of formulations, pore throat sizes, temperatures, and differential pressures. Nanotechnology remains an exciting frontier in the development of efficient, high-performance additives for drilling fluids. The ability of these innovative nanoparticles to reduce filtrate volumes and provide zero spurt loss represents a step-change in filtration control in water-based fluids. Application of these nanoparticles in well construction can allow for improved wellbore stability, reduced formation damage due to fluid invasion, and reduced NPT.