New Insight into the Filtration Control of Drilling Fluids Using a Graphene-Based Nanocomposite under Static and Dynamic Conditions

During oil and gas well drilling, the filtration control of bentonite water-based drilling fluids (BT-WBDFs), as an environmentally friendly fluid, is crucial to avoid formation damage and swelling shale problems. One of the most critical problems is undesirable changes in the rheology and filtration properties of the BT-WBDFs because of salt contamination. Herein, the potential of using both graphene oxide (GO) nanosheets and a graphene oxide-polyacrylamide (GO-PAM) nanocomposite is evaluated for controlling the filtration properties, especially in a salty medium. First, GO nanosheets were functionalized, and then the GO-PAM nanocomposite was synthesized using the solution polymerization method. Afterward, the products were characterized using scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. The rheological parameters were analyzed using power-law, Herschel Buckley, and Bingham plastic models. The filtration tests were carried out under both static and dynamic conditions. A membrane cell equipped with an agitating system was used for conducting dynamic tests. Furthermore, the static tests have been conducted under low-pressure/lowtemperature and high-pressure/high-temperature conditions. The experimental results revealed that although adding the GO-PAM nanocomposite into WBDFs, at the concentration below 1 wt %, increases rheological properties more than GO nanosheets, the rate of filtration properties was more reduced for GO nanosheets under static conditions. The obtained results showed that under static conditions, the addition of only 0.5 wt % of GO nanosheets to saline mud could reduce the total cumulative fluid loss, rate of fluid loss, and mud cake thickness more than 60, 99, and 72%, respectively. Under dynamic conditions, similar results were obtained for the shear flow of 700 rpm. However, results showed that the GO-PAM nanocomposite has better performance because of lower cake erosion under high shear flow conditions. GO nanoparticles reduce the filtrate loss by blocking the pore space in the filter cake, while in the presence of polyacrylamide, the adhesion between the particles increases, and the erosion rate decreases under shear flows. The experimental results revealed that using 0.7 wt % GO-PAM nanocomposite could reduce the erosion rate of the mud cake more than 60% under turbulent flow conditions, while this value was 20% for GO nanosheets in the same concentration.