Natural rubber latex as a potential additive for water-based drilling fluids

The environmental hazards and "carbon footprint" of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals. This paper explored for the first time the interaction mechanism between natural rubber latex (NRL) and bentonite suspensions (BTs) through a series of characterization experiments, as well as the potential applications in water-based drilling fluids (WBDF). The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient (k) and flow index (n) of BTs, and enhance the shear thinning performance of BTs as pseudo-plastic fluids. In addition, 0.5 w/v% NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles, but also facilitated the compatibility of pressure loss and flow efficiency. The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles, and optimize the particle size distribution and flow resistance of WBDF under the "intercalation-exfoliation-encapsulation" synergistic interaction. Moreover, NRL can improve the rheological properties of WBDF at high temperatures (<150 ºC), and form a dense blocking layer by bridging and sealing the pores and cracks of the filter cake, which ultimately reduces the permeability of the cake and the filtration loss of WBDF.