Engineering Analysis of Light Well Intervention Systems
Maximise operability, minimise loads and prevent overload with AS Mosley’s Riserless Light Well Intervention Services.
Riserless Light Well Intervention (RLWI) is performed using a Subsea Lubricator System that is usually deployed from a small monohull vessel. The Subsea Lubricator comprises a control package and a free-standing riser which is used to house the wireline tool string prior to deployment into the well. The Lubricator assembly is run and attached to the subsea Tree via the Tree Running Tool (TRT).
Riserless Light Well Intervention systems impose very low loads onto the Subsea Tree and wellhead during normal operations. Nevertheless, the attached lines (e.g. WL, guidelines and umbilicals) may snag during accidental vessel excursions – inducing relatively high loads. It is important to keep the wireline away from the control umbilical, especially during tool-running. Another important consideration is the length of the free-standing riser which must be intrinsically stable in all conditions. Limiting riser deflection is also critical to enable loading of the wireline tools with the ROV. Riser deflections can be amplified through second order mass effects especially at high wellhead angles in extreme currents.
AS Mosley has over 24 years of experience in modelling and performing design optimisation of Subsea Lubricator systems. We maximise operability and prevent overload even during accidental conditions. We also advise on suitable systems for minimising loads on very weak subsea equipment.
Some of the key Light Well Intervention projects AS Mosley has worked on are listed below:
- Design of a stress joint for the Helix Well Enhancer's RLWI system to optimise operability while also protecting the critical well control barriers.
- Centrica Ann: structural analysis in support of intervention operations in a 30m water depth from a DP vessel.
- Repsol Petronella: design of a safety joint which could support the lubricator riser and protect the critical well control barriers.
- Structural analysis in support of Oceaneering’s new build subsea wireline lubricator systems.
For more information on Riserless Light Well Intervention Services please get in touch.