Does High Performance Water Based Mud Offer Superior Wellbore Strengthening Benefits Compared to Traditional Synthetic Based Muds?

ABSTRACT: Depleted Fracture Gradients have been notoriously challenging for drilling, cementing and completions operations for several decades. Depletion continues to become more severe and we expect to need to deliver successful fluid systems for overbalances of between 12,000 and 14,000 psi within the next few years. Many solutions have been proposed, but the majority of deepwater drilling operations have been limited to Fracture Widths (FW) of between 1000-1400 microns when utilizing background Lost Circulation Material (LCM). The plugging of larger fracture widths have been routinely achieved when an open hole squeeze is performed across depleted sands that are exposed, but the operators experience is that properly calibrated models show that the current real time drilling limit is in this range. Additionally, when losses occur with a traditional SBM fluid system, the downhole pressure quickly falls to the minimum horizontal stress for the loss zone, and recovering full strength is very difficult. This paper will demonstrate how a High-Performance Water Based Mud (HPWBM) can be designed to withstand extreme overbalance (>9000 psi) and successfully inhibit against shales in the section. It will also discuss the execution in the reservoir sections of three deepwater wells where HPWBM fluid systems were successfully deployed. Lost circulation was induced in all three instances and this paper will demonstrate the benefits of using a HPWBM compared to an SBM for drilling through larger fractures induced by greater overbalances and recovering from major lost circulation events.