Notes

Why is subsea well intervention required?
Well intervention is the capacity to safely enter a well with well control for the goal of doing a number of tasks apart from drilling. Well intervention historically was completed with drill rigs, with an 18-3/4” BOP and 21” marine riser as the only real way of well access with well control. In the 80's, technology was developed that afforded for re-entry into wells with alternatives to the drilling well control systems and rigs for delivery of nondrilling services. As technology is developed, water depth increases, well head design evolves and well construction changes, intervention also evolves and demand grows.

Cost is actually a challenge.subsea companies in Houston cost 54% of the sum total well intervention spend on the UKCS in 2017, in line with the Wells Insight report. Another issue is not enough data about what is actually happening in wells, i.e. a lack of well surveillance. The rate of well surveillance work was just 8% of the active well stock in 2017 – and that rate is significantly less for subsea wells – despite a large prize that could be had by succeeding intervention, Copland said.

Operating models
Offering a dedicated vessel that offers full contingencies and even dive support capability, must certanly be an attractive model for operators, says Helix Energy Solutions, that has the absolute most intervention vessels and longest track record, and is soon bringing its newbuild the Q7000 semisubmersible to the market. The firm even offers LWI vessels with saturation diving capability that can help de-risk operations, by performing well surveillance and doing simultaneous diving operations, says Neil Grieg, Deputy Project Manager, at Helix Well Ops, element of Helix Energy Solutions. These capabilities can help reduce subsea well plugging and abandonment costs by doing more of the job that rigs would do, he says.

The subsea well intervention work with one three-well project was done at $12 million under budget (final cost $8 million) with a 100% success rate, says Mokhtar. New technologies for the region have as also been deployed, including perforate, wash and cement (PWC), cement packers and Ampelmann walk-to-work systems. In total, 22 projects have now been run and 75% more production has been achieved underneath the project, which closed out earlier this year.

A large part of the success was based on having an integrated model, promoting collaboration and risk sharing, he says, while cost savings were produced by just utilizing the right operating model.
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