Nano Additives in Water Based Drilling Fluid for Enhanced-Performance Fluid-Loss-Control

Abstract

Drilling fluid which is also known as drilling mud is a crucial element in oil and gas exploration process as it used to aid the drilling of boreholes into the earth. Among other functions, drilling fluid needs to carry drill cuttings to the surface of the well, support the walls of the well bore, provide hydrostatic pressure to prevent formation fluids from entering into the well bore, cool and lubricate the drill bit, prevent drill-pipe corrosion, facilitate the attainment of information about the formation being drilled, and create a thin low-permeability cake that protects permeable production formations. Water-based mud (WBM) is the most common drilling fluid used in oil industry. WBM is an expensive complex chemical system that is usually mixed with filtration-loss-prevention additives such as clay, lignite, or organic polymers, with bentonite clays being very common to control the fluid-loss during drilling process. These traditional additives are able to give an average fluid loss of 7.2 mL over 30 min and leaving a filter cake ∼280 μm thick. Graphene, as a single layer of graphite which is also considered nano-additive, has become the subject of much research interest for its unique materials properties. A pristine graphene monolayer has a theoretical surface area of 2965 m²/g and has been shown to form a membrane impermeable even to helium gas. This work presents the recent progress of using nano-materials such as graphene as an additive in WBM. Most recent report showed that graphene has the potential to decrease the fluid loss by ∼15–20% (due to its large surface area with very thin 2D layer, only 1 atom thick) compared to that of WBM with conventional additives, and to reduce the filter cake thickness up to ∼20–50 μm, which in turn can help to increase the oil production rate. In addition, adding graphene to WBM solutions is expected to lead to greater shear thinning and higher temperature stability compared to clay-based fluid loss additives.