1. Lesson Learnt From A Sub-Sea Well Intervention

2. Lessons Learnt From A North Sea Sub-Sea Well Intervention Background. 2010 Following a plant shut down the sub-sea well would not restart. Surface tests indicated it was either a failure of a TR-SC-SSSV or the Matrix. 2011 Sub-Sea Intervention planned with a Light Well Intervention Vessel (LWIV). The plan was to investigate why the well would not flow. The well had been drilled by a 3 rd party turnkey operation 10 years previously. No well interventions had been carried out during the interim period. The well was completed with a sub-sea horizontal tree.

3. Lessons Learnt From A North Sea Sub-Sea Well Intervention Learning. For older sub-sea wells use a resilient AX seal for wellhead to LWIV interface.

4. Lessons Learnt From A North Sea Sub-Sea Well Intervention Be prepared for the unexpected.

5. Lessons Learnt From A North Sea Sub-Sea Well Intervention Unable to pull 2 nd Crown Plug. Normal slickline bailers made no head way. A Welltec brush had been mobilised to clean the TR-SC-SSSV. A Weltec Vacuum tool had also been mobilised.

6. Lessons Learnt From A North Sea Sub-Sea Well Intervention Rope and propant were recovered from the top of the 2 nd Crown Plug. Drilling Well Reports stated the Crown Plugs had been set on drill pipe.

7. Lessons Learnt From A North Sea Sub-Sea Well Intervention Take a Camera. An Expro camera had been mobilised to check the operability of the TR-SC-SSSV. Camera had side view option and found a 360 degree tubing indent anomaly. Photo 1 shows top of flapper in TR-SC-SSSV. Photo 2 shows debris at top of TR-SC-SSSV internal flapper sleeve. Photo 3 shows indent anomaly in tubing above TR-SC-SSSV.