Novel Biopolymer Decreases Formation Damage for Water-Based Drill-In Fluids

Abstract Drilling operations using water-based fluids (WBF) is environmentally convenient for certain fields around the world. However, for very reactive formations, WBF could be detrimental due to incompatibilities, creating challenging drilling operations and negatively influence production. WBF must be inhibited for clay/shale interaction and corrosion, very lubricious, with minimal filtrate invasion. If a WBF is used to drill reservoirs, the design complexity increases aiming negligeable reservoir damage and compatible with formation fluids. Polymers such as xanthan gum (XG) are used to formulate WBF; it provides viscosity and carrying capacity. The damage caused by the XG could be removed using breakers, but extra steps aren't always desirable by operators. Therefore, a new biopolymer was created to replace the XG aiming to decrease damage and remove the need for a breaker. WBF were formulated using XG or the novel biopolymer. The fluids were subjected to several tests including rheology, fluid loss, accretion, shale-particle disintegration, and return permeability. All with the goal of predicting compatibility with the reservoir and behavior while drilling the reservoir section. The two WBF were tested side by side. The novel biopolymer is capable of creating viscosity and carrying capacity similar to XG. When the novel biopolymer is used to formulate the fluid, return permeability in limestone cores for producers increases from 55.7% to 89.7% and the filtrate invasion inside the core decreases from 79% to 29%. Lift off pressures were below 10 psi for both fluids and no differences were observed when accretion (90%) tests were performed using London and Nahr Umr clay. Nevertheless, the interaction between all WBF components must be studied carefully. Synergistic effects must be considered when formulating the fluid. Inhibitors such as clay, oxygen, and corrosion could impact the filtrate interaction with the near wellbore in the reservoir and change the return permeability results. Novel biopolymers used to formulate WBF decreases damage to the formation while maintaining synergistic effects with other components. The result is a less damaging fluid to reservoir with improved capacities.