In 2019 the Armada hub was evaluated for drillable targets to exploit previously untouched reserves and extend the life of the platform. Seymour Horst oilfield, the most eastern of fields served by Armada, was discovered in 1983, and appraised the same year. These wells were drill stem tested in multiple zones, but all had low production rates. Reservoir simulation work estimated that drilling and completing a long horizontal well in Seymour Horst's upper and middle Skagerrak sands followed by multi-stage hydraulic fracturing treatments to overcome reservoir compartmentalization and low vertical permeability would bring the well to economic rates. Well 22/5b-A14 was sanctioned and drilled in 2019/2020.

Execution of hydraulic fracturing campaigns in long horizontal wells in the challenging North Sea environment is complex, with great emphasis on operations efficiency. Considerable time was put towards each element of the well construction and job design, including the modelling of reservoir characteristics critical for fracturing, multi-stage fracturing completion design, fracturing materials, management of resources onsite during execution, and the design of the CT string to be used as contingency. This paper describes the detailed planning process and utilization of a combination of new North Sea technologies and operational techniques to successfully execute the campaign with large proppant volumes in the high temperature reservoir, in a challenging offshore environment, in an efficient and cost effective manner.

Over 40,000 Bbl. of clean fluid and 2,500,000 lbs of 16/20 resin coated ceramic proppant with ~7.5% of that volume being infused with scale inhibitor, was pumped into the well from the dedicated stimulation vessel. The campaign was executed over the winter months in 2020, and therefore was subjected to waiting on weather delays. As a result, the vessel operating efficiency was 11% vs the estimated 22%. However, the use of the ball actuated multi-stage system eliminated five of the seven intervention operations that would have been required in a conventional completion system between each stage, saving valuable rig time, and allowing the stimulation vessel to maximise the use of the operable weather windows. Further time savings were made through use of water bunkering operations, reducing the number of sailings required by the stimulation vessel to place such a large volume of fluid and proppant. Production rates, while initially lower than expected, remain sustained. There have been no issues with scale to this date.

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