Dual-gradient drilling (DGD) is an emerging technology that will enable operators to drill in environments where mud weights are quite high and formation fracture pressures are quite low. This step-change technology will allow access to deepwater reserves and will fundamentally change the way deepwater wells are drilled.This paper describes the planning and preparation for the world's first dual-gradient well in Green Canyon 136. Our objective was to deliver a functioning and proven DGD system for commercial application in deepwater environments. The dualgradient system worked as designed, and 100% of all critical objectives were successfully met.
Chevron is working with AGR Subsea, Pacific Drilling, GE Oil and Gas, and others to deploy the world’s first commercial Dual Gradient Drilling (DGD) System. The DGD system will be installed on a Pacific Drilling Samsung 12,000 Class rig currently being built in Korea. It is expected to begin operations in the Gulf of Mexico in 4th Qtr 2011. This paper will detail the design, fabrication, testing and preparations that are being made for that deployment.
Not only is significantly new hardware being added to the rig, but a new set of processes and concepts are being embedded in the drilling organization to take full advantage of the hardware. This has required the simultaneous development of two different, but linked, work streams: hardware and personnel. The “hardware” side of the work has concentrated on the integration of completely new equipment into the rig to make it DGD ready. This includes a subsea pump, a completely new riser, several riser “specialty” joints and all the rig modifications required to handle, run and support this new drilling system. The “people” work stream includes the development of drilling and well control procedures, well planning and the extensive personnel training needed to realize all the benefits of the technology.
This effort has impacted every facet of the Chevron deepwater drilling community. Chevron has reexamined the way rigs and drilling assets have historically been deployed. This has resulted in the development of a “Value Driven Drilling Schedule” to optimize utilization of the technology.
The DGD system could revolutionize how deepwater wells are drilled and how deepwater assets are explored and developed.
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