During the recent development of the Zhao Dong field in Bohai Bay, a One-Trip Multizone Sand Control System was combined with frac pack treatments for efficient completions in a series of stacked pay sands. These technologies were used to complete a total of 32 zones (28 frac packs and 4 circulating gravel packs) in eleven wells, in record time. This paper examines the factors that contributed to the success of these operations.

The One-Trip Multizone Sand Control system allowed pumping operations on each well to proceed with little or no interruption. While frac fluids were being prepared between pumping each zone, downhole sand-control equipment was repositioned and ready for the next frac pack. This allowed all of the frac packs on each well to be done in a few hours instead of days typical of this type of completion.

For the majority of the zones that were pumped, a mini-frac analysis was performed prior to redesigning and pumping the main frac job. The One-Trip Multizone tools allow live annulus data to be collected for a measure of the bottom hole treating pressure while the mini-frac is being pumped. However, once pumping has stopped on the mini-frac, pressure from the annulus does not allow actual monitoring of the pressure decline on the formation. The solution to this problem is discussed.

Due to rig space limitations, none of the frac equipment could be placed on the platform. It was placed on floating vessels in order to pump the frac packs. There was also shallow water depth around the platform. To help solve these logistical problems, two vessels were required. A fluids barge was refitted with the proper tankage and centrifugal pumps for moving drilling and completions fluids to the rig site. The other vessel was used as a platform for the pumping equipment, with all fluids mixed and stored on the fluids barge. This combination allowed pumping operations in preparation for each frac pack to proceed smoothly, without interfering with other rig operations.

Lessons learned about proper zone spacing, pre-job planning, and well preparations are also discussed.

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