Reliance Industries Limited (RIL) India has drilled the well (GS01-M1) using Managed Pressure Drilling Technology (MPD) as part of its exploration program. Well GS01-M1 was the fourth exploratory well drilled in the GS – OSN – 2000/1 Mumbai offshore basin with the objective to test thehydrocarbon potential of the carbonate reservoirs of Late Oligocene and Mid Eocene. Since a narrow operational window between the formation pore and fracture pressures was expected, the used of two variants of the Managed Pressure Drilling technique were planned for this well to be utilized depending on the formation requirements. The Constant Bottom Hole Pressure (CBHP) technique, one of the MPD variants, was selected for the primary purpose of controlling the drilling fluid Equivalent Circulating Density (ECD) and to be capable of maneuvering the drilling fluid’s density through the narrow formation pore pressure andfracture pressure window. In addition, as operational window between formation and fluid losses pressure could get closed, leading to the boundary where these losses are uncontrollable by mechanical means, the drilling mode could be switched to the Pressurized Mud Cap Drilling (PMCD) technique which will allow drilling with no returns on surface injecting down the drill pipe and into the formation sacrificial fluid whilst the annulus is closed at the MPD choke and maintained full of high viscosity mud. This technique takes the advantage of the natural ability of the fractured formation to take both, injection fluid and drilling cuttings. The Managed Pressure Drilling technology used to drill the 12-1/4" and 8-1/2" hole sections of well GS101 – M1, accurately allowed to control the downhole pressure profile according to the real time Pore Pressure calculations performed while drilling based on MWD logging tools thus, the balance between the limits of the fluid losses and the formation influx pressure was ascertained and by means of surface back pressure adjustments, this balanced bottom hole pressure condition was maintained. Operations were conducted from a semi submersible drilling rig equipped with a 10K psi sub-sea BOP stack. In order to increase the pressure rate in the marine riser from 500 to 2000 psi to enable the MPD operations, a 13-3/8" casing was used as a concentric riser hanged from a flange connector which was nippled up onto the marine riser expansion joint. This assembly allowed to rig-up the surface MPD stack for flow and pressure control. The 12-1/4" hole was drilled from 2168 m to 3805 m in 27 days since the 13-5/8" casing shoe was drilled out until the 9-5/8" liner was run and set. Another 6 days were used to drill the 8- 1/2" hole section from 3805 m to 4326 m. In both cases, the ECD was managed combining the friction loss pressure in the annulus and the back-pressure produced by the MPD choke; 500 psi of kick tolerance was used as safety margin for the maximum allowed casing pressure in dynamic conditions as Reliance and the drilling contractorwell control policies. The application of the CBHP technique reduced the NPT experienced in the drilled off-set wells in the same basin by controlling the mud losses and formation influxes events associated with the drilling of fractured limestones. This paper describes the Front End Engineering Design, Project Management, Risk Mitigation, Detailed Engineering & Design, Operational Results and Lessons Learned from this project.

Subsea blowout preventer (SBOP) reliability is a major challenge in Deepwater Drilling & Completion operations, accounting for one of the major equipment failures and Non-Productive Time (NPT) costs yearly. This paper focuses on SBOP technological advancement since the Deepwater Horizon/Macondo incident in 2010, with additional emphasis on reliability, equipment condition monitoring and statistical root cause analysis. After finishing a deepwater well, the SBOP must undergo maintenance, repair if needed and pressure testing before being deployed on the next well. The rig owner is under great pressure to complete this turn-around to avoid waiting time. On an average, in-between wells, rig contractor took approximately 2.6 days extra time (NPT) waiting after completing top hole to get ready to deploy SBOP during 2019-20 exploration and appraisal campaigns. This can be critical during development campaigns where number of rig moves are involved quickly or in cases where top holes are batch drilled the waiting time for SBOP readiness can be as high as 7-8 days per well. Some operators are collaborating with drilling contractors in number of ways to arrange for a second fully assembled and (offline) pressure tested SBOP to be available on the rig (Dual SBOP); deployment of additional trained subsea engineers for performing maintenance/repair. SBOP pressure-testing time can also be drastically reduced by using comparative pressure-testing software to eliminate human error and accelerate pressure testing. Furthermore, leak detection time can be eliminated by installing sensors, and real-time test monitoring providing increased reliability with the additional advantages that conditional monitoring can be enhanced with the same digital sensors. SBOP dashboard that simplifies existing diagnosis and allow remote monitoring of the subsea SBOP control system will improve communication of SBOP health also serve common platform across rig fleets that allow standardization of SBOP diagnostic data and aids in operational decision making Ensuring additional SBOP redundancy especially while operating Emergency Disconnect System (EDS) available through Remotely Operated Vehicle (ROV) control panel or acoustic system. In addition, it is mandatory for the SBOP to have Autoshear and Deadman systems to be able to shut in the well in case of an emergency. Furthermore, technological workshop with several major service vendors have being held to ascertain current advances like Multifunctional profile, Accumulator recharged by ROV, ROV DP system, An Auxiliary Accumulator System and upgraded Acoustic System. In the end, the development of new technologies applied for the SBOP targets the overall cost optimization of the well lifecycle but also assure SBOP functionality. This paper is intended to provide considerations for operators in developing their future campaigns to frame scope of work for SBOP and rig contracting strategy.