During early exploration of the southern North Sea, directional drilling techniques were not yet available. As such to increase the reach of individual platforms wells were drilled on a slant from surface. Although wireline intervention was achievable using bespoke Altus Intervention equipment, some wells in field called for CT intervention. No equipment existed to allow this. As such, the Altus Intervention team was challenged with realising this assignment.
The Altus Intervention operations and engineering teams worked closely to devise a solution allow the CT injector head and PCE to be positioned at such an angle as to allow access to the 30 degree slanted wells. Fully designed in-house, this manifested itself in the bespoke Slant Well Intervention Mast (SWIM). The unit allows movement in the x, y and z axes and is designed to operate in a zone 1 area. Furthermore, the unit comes in under a 20Te single lift weight limit.
Coupled with a purpose designed skidding system, the SWIM allows interventions to be carried out on the previously inaccessible slant wells.
With design and manufacture completed various yard trials were completed. The unit was then mobilised offshore to intervene on 2 wells. The wells were suffering from lower than expected production due to scale and debris obstructions.
The SWIM was successfully rigged up and a CT fluid cleanout followed by a foamer and N2 lift remedied the downhole issues. The wells were brought back online with minimal downtime and no HSEQ issues.