Access to new reserves and subsequent production is becoming a challenging scenario for oil and gas companies all over the world. In this particular context, a major operator planned an onshore well in Pakistan (located 350km north of Karachi) as part of a revamped drilling campaign in this mature field. However, in previously drilled wells in the vicinity several drilling issues were encountered including, but not limited to, a challenging drilling window with kicks and losses. These are mainly due to formation structural conditions that require very strick control of the equivalent circulating density (ECD) and the equivalent static density (ESD) for new wells drilled in the area. If successful operationally and if reserves prove economically exploitable, this well will be used as potential reference for future infill drilling in this reservoir. To overcome the issues and ensure the greatest potential to successfully drill this well, it was decided to use managed pressure drilling (MPD) equipment for the last two challenging well sections. Because of this, a full dynamic drilling modelling solution was selected to support the planning phase and subsequently, the decision process during the operations. The dynamic models applied include consideration of temperature, pressure, mud compressibility and rheology as well as gel breaking effects in a transient simulation. For well control considerations a two-phase model considers both influx of the reservoir fluid and modelling of the fluid properties by equation of state as well as distribution and migration of the influx in a drilling kick scenario. As direct result of this study, it was decided to revise and slightly adjust the optimized drilling fluid weight to better manage the ECD/ESD, thereby avoiding compromising the integrity of the well during the operations. Some of the specific parameters were re-defined based on the modelling results, providing enhanced best practices for the MPD utilization. The implemented approach required the drilling practices to be tailored for this particular well and opened the opportunity to implement the lessons learned into the company well design process and drilling practices. For this, a multi-domain collaboration is key to minimize the uncertainty associated with the behavior of the drilling dynamics with respect to the drilling window and the overall operational system. In addition it requires the inclusion of dynamic modelling to provide a more realistic planning approach makes it possible to consider different drilling opportunities in mature fields with challenging profiles. This paper will describe the analysis done using this dynamic drilling modelling approach, with focus on the primary and secondary well control.

Ever evolving drilling performance requirements dictate bits drill wider ranges of lithologies while offering improved efficiency and reduced NPT. These performance requirements necessitate compatible drill bit technologies. As lithologies associated with these drilling objectives tend to be harder and more abrasive; the need for adaptable, durable, and efficient drill bit designs is intensified. With these challenging applications / objectives, Polycrystalline Diamond Compact (PDC) technologies are pushed to their material limits. These limits emerge as failures in PDC thermal fatigue, abrasion, and impact damage.Due to the absence of state-of-the-art drill bit material technologies compatible with achieving these drilling objectives, multiple trips are commonly required. Often, this translates into the use of non-PDC bits (Rolling Cutter and Impregnated) to complete challenging sections. As efficiency is hindered by bit type and increases in non-productivetime due to multiple bit trips, operators incur significant cost while drilling these intervals.New drill bit technology capable of drilling these lithologies and performance requirements is unmistakably needed. This paper describes the development of novel drill bit technology aimed at this requirement. This technology is born through the fusion of existing bit technologies; Fixed Cutter and Impregnated Diamond, and a unique design philosophy providing greater versatility in drilling a wider range of harsh lithologies, not typically drilled entirely with PDC bits. This novel design philosophy includes optimized cutter placement and exposure of diamond impregnated mix applied in critical areas of the bit.This project was initially targeted at the Sub-Saharan region in the Congo, where the existence of conglomeratic intervals still represents a challenge to reach TD in a single run for sections with high clonglomeratic percentage. In its first trial, the new technology hybrid bit drilled 300% more interval than the benchmark with 34% improvement in ROP, in comparable sections with similar conglomerate content. Subsequent runs have resulted in dramatic savings due to reduction of trips as well as improved ROP. This technology has provided the industry step change in performance and decrease in non-productive time.