Atila Fernando Lima Aragao

Successful Application of MMH Fluid to Drill in Narrow Pressure Window, Ultra Deepwater Situation. A Case History

A mixed metal oxy hydroxide (MMH-type) system, which exhibits unique flow and gelation characteristics, was used to successfully drill an ultra deepwater well offshore Brasil. Despite ECD values that exceeded the measured leak off pressure and the calculated fracture threshold for the shale, no losses of fluid to the formation were reported. Subsequently rheological investigations of laboratory-prepared and field fluids were carried out under temperature and pressure conditions similar to those encountered on the subject well. The study unveiled unusual temperature responses of some key rheological measurements. This phenomenon may have played a part in the successful completion of the application discussed. Further work is being undertaken to better understand both this phenomenon and its implications for field application. This paper discusses the development and application of the MMH fluid that is now a real alternative for the operator in deepwater applications where narrow pressure window circumstances have to be addressed.

Well Construction Hydraulics in Challenging Environments

Hydraulics plaies a major role in well construction, especially in narrow operational window scenarios, where the difference between pore and frac pressures approaches zero. Besides, special geometry wells, where annular friction losses contribute expressively to downhole pressures, are becoming attractive alternatives to enhance production. Efficient drilled cuttings transport, minimizing contamination in fluid substitution operations and gravel packing are critical operations to be performed. The hydraulic targets for such projects require multidisciplinary technological development, including real time monitoration of downhole pressure, density and friction reduction concepts, chemicals and equipment, rheology optimization and reliable multiphase models. This article focuses on the application of latest design, chemicals, software, and equipment technology for drilling and completing (including sand control) in challenging scenarios, such as ultra deepwater exploratory wells, extended reach offshore wells, 2000 m horizontal section in shallow water carbonate reservoirs, 1200 m horizontal section gravel packing in deep water non consolidated sandstone reservoirs, managed pressure drilling onshore experiences, extended reach onshore wells for offshore reservoir exploitation, including slant rig drilling and open hole gravel packing with synthetic low viscosity fluids. Finally, the hydraulic challenges for the future will be highlighted.