The drilling project was aimed to develop an offshore salt field with salt cavern from an onshore location in The Netherlands. The well was planned with a 3314m step-out from the surface location at a depth of 3021m TVD. At the target the well needed to be vertical again to be able to safely develop the salt cavern, this resulted in an S-shaped trajectory. Main objective for the well was to be able to produce brine with freshwater injection rate of 450m3/hr. To achieve this objective, it was considered crucial to get the planned (13-3/8” x 14”) last cemented casing string to final depth at 4539m MD.
The design resulted in the following casing configuration: 30”- 24” – 18 5/8” – 16” – 13 3/8” – 11 ¾” – 7”. The step out and S-shape resulted in a tangent of 68deg, with an early and sharp build-up in the lower North Sea group.
The drilling rig capabilities were a key parameter for the success of the project, >450ton >50 ft.lbs (120rpm) and >3450HP pump power. The KCA Deutag T-46 was used and upgraded with a BENTEC750 topdrive to be able to supply the required torque.
Drilling operations started in November 2019 and lasted until August 2020. The combination of the large casing (and wellbore) requirements in combination with the challenging well trajectory resulted in various drilling challenges that needed to be overcome. The well was successfully drilled to a total depth of 4941m MD / 3011m TVD and installation of the leaching strings (7” & 11 ¾”) took place as planned. Thanks to the efforts of the total team the well was finished as per design and is currently producing salt.