Abstract Filtration loss control, rheology properties, and a good knowledge of the sealing integrity of water-based drilling muds (WBDM) are some of the important factors for successful drilling operations, particularly when considering high-pressure and high-temperature (HPHT) fields. Although various research carried out in the past have shown that the application of nano-silica particles (NSP) on water-based muds improves filtration control, however, the impact under high pressure and high temperature with Polyanionic Cellulose Low Viscosity (PAC-LV) is undermined. This study assesses the interaction between NSP and PAC-LV on the rheology and filtration control of complex water-based drilling muds (WBDM) under high-pressure high temperatures. Furthermore, an attempt was made to examine the sealing integrity of SNP when combined with PAC-LV on the WBDM in a 1mm simulated fracture for 10 minutes, and the findings were compared with the widely used nutshell. This was done using a stainless-steel slotted filter disk. The yield point, apparent viscosity, and plastic viscosity of the WBDM were all improved by 403%, 318%, and 414%, at 78oF and 393%, 285%, and 577%, at 450oF respectively, according to the data. The fluid loss of the WBDM was reduced by 64% and 62% at 78oF and 450oF respectively, aging showed a slight decline in the effect. The experimental results demonstrated that the inclusion of an optimal concentration of PAC-LV lowers the risk of differential sticking and stops formations from sloughing into the wellbore. Finally, it should be emphasized, that the NSP and PAC-LV in the drilling mud improved the seal integrity and produced better results than the frequently employed nutshell while also being more resilient to deformation.

Keywords: Polyanionic Cellulose Low Viscosity (PAC-LV), nano-silica particles (NSP), water-based drilling muds (WBDM), and filtration control