Abstract

A North Sea case study detailing the completion and stimulation design of the world's first offshore acid fractured multistage dual lateral will be presented.

The key driver behind this subsea completion technology and stimulation program was to implement a cost effective completion solution that reduced field development costs. The completion technology selected provided an economically viable and low-risk solution in an economically challenging hydrocarbon environment. The completion design was developed to access two separate carbonate gas reservoirs from a single main bore. The stimulation program for the two horizontal laterals was modeled using reservoir characteristics and key considerations. The stimulation program maximized resource efficiency by utilizing the fluid capacities available within one sailing of the stimulation vessel per lateral, totaling 28 acid fracture treatments.

This novel offshore acid fractured dual lateral was drilled, completed and stimulated within three months. The horizontal section of the motherbore was completed using a 14 stage openhole multistage completion solution in three days. To reduce time on location, the well was stimulated after reaching setting depth via a tie-back fracture string. The motherbore was stimulated with individual and distributed acid fracture treatment via sequential ball-activated sliding sleeves. Once operations were complete for the motherbore, a whipstock packer was set and the second horizontal wellbore (Leg 2) drilled. The E1 Leg 2 wellbore was completed in only two days using the same technology and setup as the motherbore. Once the bottomhole completion was set, Leg 2 was stimulated with 14 stages of acid fracture treatments, using the same sized ball-activated sliding sleeves as in the motherbore.

By implementing a flexible low cost completion solution and maximizing the resources available during stimulation, the world's first offshore acid fracture multistage dual lateral was successfully completed, requiring only one subsea wellhead and tree. The completion and stimulation program of this dual lateral project provided a high value solution to North Sea operations by minimizing time, resource utilization and expanding experience for future ventures.

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