In the present study, we synthesized graphene oxide nanosheet (GONP), polyacrylamide (PAM), and a graphene oxide nanosheet/polyacrylamide nanocomposite termed as GO/PAM nanocomposite with varying GONPs-loaded (0.5, 1, 1.5, and 2 wt% in proportional with monomer weight) using a solution polymerization in aqueous system and investigated their application as a novel drilling-fluid additive. The primary goal of the study was the experimental investigation of the effects GONPs, PAM, and GO/PAM nanocomposites as an additive to the water base drilling fluid (WBDF) over rheological properties before and after hot rolling, filtration properties at low and high pressure and temperature conditions (LPLT and HPHT), weight and pH of mud, and thermal conductivity of modified drilling fluid compared to WBDF. Herein, required GONPs were synthesized by simplified Hummer's method at room temperature in which there is no temperature control during the reaction and successfully characterized. Thermal conductivity analysis showed that thermal conductivity of WBDF in presence of GONP/PAM nanocomposite as an additive improved compare to the pure PAM. (C) 2020 Elsevier B.V. All rights reserved.