Hoover-Diana Deepwater Drilling and Completions

Abstract

Hoover-Diana is a deepwater Gulf of Mexico oil and gas development. The reservoir development plan is a hybrid drilling and completion program encompassing remote subsea wells (Diana) connected by flowlines to a host DDCV (deep draft caisson vessel) and platform-type wells (Hoover) on the DDCV with surface trees connected to the seafloor by production risers.The Diana subsea wells were batch drilled with a dynamically-positioned drillship and then completed with a new-build, moored semisubmersible. These subsea wells were designed as horizontal open-hole gravel packs to deplete a relatively thin oil rim that lies between an aquifer and a large gas cap. The horizontal sections of each well were drilled and completed with the subsea tree in place, and all wells were flowed back to the drilling rig for clean-up and hydrate prevention prior to installation of the DDCV and flowlines. At the time, these were the deepest water-depth horizontal wells in the world. Numerous challenges were encountered in the design and construction of these wells, including the scheduling aspects associated with the two deepwater drilling rigs and pipeline installation vessels.The Hoover drilling program required significant upgrades of an existing API-type platform rig combined with unique modifications to accommodate DDCV motions and riser systems. The Hoover drilling and completion program is a mixture of cased-hole frac pack wells and open-hole, horizontal gravel pack wells. Furthermore, it marks the first time a drilling rig would set subsea wellheads from a caisson vessel and perform all of the drilling and completion operations including the riserless operations.

Large Floating Structures

“…Installation of the production riser tensioners in shown in Fig. Spars have been used for both drilling and workover of wells (see Moyer et al 2001;Bates et al 2001;Glanville and Vardeman 1999). These utilize hydraulic cylinders oriented with Fig.…”

Floating Offshore Platform Design

“…The spar has been used for drilling and workover of wells (see Moyer et al, 2001, Bates et al, 2001, Glanville and Vardeman, 1999. The Genesis, Diana and Holstein spars are equipped for full drilling using platform rigs.…”

Reducing Well Cost by Gravel Packing in Nonaqueous Fluid

“…2 Since Angola Block 15 required an openhole gravel pack, displacing the NAF to brine based completion fluid prior to gravel packing was identified as one of the most critical steps during the pre-development risk assessment. If hole instability problems were encountered after displacing the openhole to brine, the contingency plan would include pulling the screens, displacing the hole back to NAF and running a 7-5/8" perforated liner as in the previously mentioned West Africa development.…”