Predictive modelling of the impact of silica nanoparticles on fluid loss of water based drilling mud

Research into the use of nanoparticles for drilling mud formulation is gaining momentum but a key challenge involves predicting the effect of nanoparticles on the properties of the modified mud. Mathematical models used in the description of drilling muds allow for a generalised computation of drilling performance. In other words, such models cannot quantitatively capture the contributions of nanoparticles to the overall performance of the nano-modified drilling mud. In this work, a new model was derived which describes the fluid loss of nanoparticle enhanced water based drilling mud under static filtration. This was done taking into account the structural kinetics of the bentonite suspension and colloidal behaviour of the nanoparticles. The new fluid loss model was compared with the known API static fluid loss model using statistical measures, Root Mean Square Error (RMSE) and Coefficient of Determination (R-2). The new model compares favourably with the API static model with RMSE and R-2 values of 0.41-0.81 cm(3) and 99.3-99.89% respectively. The new fluid loss model was able to predict a value for the maximum fluid loss. It also accounted for variation in mud cake permeability and solid fraction, which could not be explained by the API fluid loss model.