The use of water based mud (WBM) in drilling applications under extreme Pressure and temperature has been increasing rapidly in the drilling industry over the past few years. It is now more crucial to close the technological gap that presents challenges towards developing high Density water based mud systems for High Temperature High Pressure (HPHT) wells. These challenges include rheology control, weighting agents sagging tendencies associated with high down hole temperature, In addition to the high solids loading which limits the free water availability impacting polymers performance and therefore, rheology, HPHT fluid loss and filter cake thickness control become an issue that requires special optimization and extra field maintenance. Operating under narrow margin between pore pressure and fracture initiation pressures adds to the complexity of the drilling fluids maintenance where a slight change in the bottom hole pressure (BHP) could lead to significant increase in the non-productive time "NPT" due to the time spent in solving possible fluid losses and kicks. This paper discusses the outstanding performance achieved in a deep HPHT formation drilled using water base mud weighted with Manganese Tetroxide (Micromax)/Barite blend, from planning and extensive lab testing to field implementation. This paper also describes and compares the methodology of using Micromax/Barite versus using barite only as the weighting agent and finally the field results.

Objective Mesophase is a spotting fluid, along with an organic acid which will serve to remove filter cake matter, equalize differential pressure, and free the pipe. Methodology Herein is a case history of a successful application using mesophase technology for stuck pipe incident in lateral reservoir section align with wellbore cleanouts. Stuck pipe is a major operational challenge that causes a significant amount of downtime and high costs during the operation. Filter cake can significantly cause stuck pipe incidents and reduce the efficiency of the production rate of a well. This paper describes an engineered and cost-effective approach to overcome stuck pipe events. This approach is based on removing emulsions, dissolving acid soluble solids, dispersing non-solute and water wetting all surface. The mesophase restoration system is a customized, and designed to remove mud damage, in-situ emulsions, oil-based mud (OBM) filter cakes in the well bores. Results Selection of an appropriate clean-up procedure is critical in ensuring the productivity of open hole wells, particularly horizontal wells. The mesophase system was pumped ahead after pumping the spacer train. The system contains a proprietary surfactant blend, organic acid, corrosion inhibitor, and brine that are all spotted into the stuck spot in the hole and allowed to soak. During this soaking process, the ultra-low interfacial tension properties of the breaker solution begin to diffuse, solubilizing the oil in the emulsions and dissolving the filter cake while dispersing undissolved solids and allowing the pipe to be freed. Novelty The success of freeing a stuck-pipe depends on two main factors – the correct diagnosis of stuck-pipe event either to be differential or mechanical stuck, and the right decision to implement the remedial treatment quickly and effectively. Applying the mesophase fluid technique saved the non- productive time (NPT). This technique is a reservoir friendly and has been successfully implemented in stuck-pipe events in oil-based drilling fluids.