EFFECTIVE well intervention is key to prolonging and sustaining the life of brown fields, especially in the North Sea, says Daniele Petrone, current chairman of the Intervention and Coiled Tubing Association European Chapter (ICoTA).
“We see that as a core issue, a key challenge and, at the same time, it’s happening,” said Petrone, before the 16th SPE (IcoTA) European Well Intervention Round Table, to be staged in Aberdeen, November 17-18.
“Without well intervention, the many mature fields in the North Sea will face a faster decline than would be the case if there was a more strategic approach to well maintenance/ intervention.”
This is exacerbated by the fact that a significant proportion of the North Sea’s well stock is old and perhaps not in as good condition as it should be.
Petrone added: “I is extremely important to keep the wells in as good a shape as possible. While in the past it may have been easier to find new reserves to replenish, this is becoming more and more difficult. The industry has got to look after what it has.
“Yes, they’re making more oil and gas discoveries, but smaller than they used to be. Making the best of what is out there already is definitely a strategy that should be pursued.
“Fortunately, a number of major operators understand that one of the keys to what is regarded as one of the “holy grails” of the industry – enhanced oil recovery – is effective intervention. That way they can win extra barrels for a relatively small investment.”
Petrone agreed that, until relatively recently, most of the conversation about prolonging the life of the North Sea tended towards ensuring that platforms and pipelines were in good condition and drilling infill wells, but that not a lot of emphasis was placed on intervention to boost the output of the existing well stock.
“Intervention has often been an industry ‘Cinderella’,” said Petrone.
This is reflected in the relatively late appearance of vessels capable of rigless intervention – companies like Island Offshore and Helix Wellops – and which are able to carry out well interventions at a much lower cost than is possible by employing a mobile offshore drilling unit (MODU) for the purpose.
The big barrier to the appearance of suitable vessels and associated well intervention equipment has traditionally been the cost of rig time.
Petrone: “Intervention is a very cost-effective way of maximising oil and gas recovery, especially when you can avoid using rigs.
“Anything that can be done to avoid rigs, such as carrying out intervention from supply vessels, specialist ships and from the drill-floor of a production unit, means a higher margin can be achieved on every barrel of hydrocarbons produced. The impact can be dramatic in value terms.
“Secondly, in the past, few operators have seen well intervention as a more cost-effective way than simply drilling new wells.
“In the past, when fields were younger, more prolific and easier to handle, there would have been greater advantage in drilling than carrying out intervention. But with maturing fields, intervention is very important.”
While he acknowledges that tight gas and maybe even shale gas are set to become significant in the UK and Europe, Petrone believes there remains a lot of conventional gas to play for in the North Sea but that this will require better reservoir management to realise the full value of the prize.
“That is now whereas I think tight gas, for instance, is a bit in the future. But it will come,” he said.
Turning to the deeper waters of the Northern North Sea and UK Atlantic Frontier, Petrone said the biggest risk and hurdle to overcome is the cost of doing intervention. Most is rig-based. This is, of course, expensive. But when it needs to be done it is being done.
He added that some operators had plans to install permanent intervention facilities on some platforms but this aspect has been delayed significantly.
Might light well intervention vessels be a way into that area?
“I hope so,” said Petrone. “But this remains relatively new. Until last year, I would say, there were very big constraints on the number of vessels. Quite simply, they were not available so that restricted what might have been possible. Some operators still see this approach as high-risk.
“In this sense, Norway has been leading the way … deep water, much the same weather as the UK. A lot of successful work has been done.”
Petrone pointed out that the financial crisis of 2008-09 did not help, nor did the brief crash in oil prices.
“This set back progress, on subsea well intervention especially, by a couple of years or so,” he said.
“But I think that, in the long-run, subsea well intervention will become commonplace. With more and more subsea developments, including west of Shetland and the Barents Sea, the issue of effective well intervention becomes increasingly important if well productivity is going to be sustained.
“Anything that can be used to reduce the cost and make vessels and equipment more accessible will be welcomed.
“And if you can convince operators that they don’t need a rig anymore and that you can carry out efficient well intervention from a standard supply vessel, of which there are plenty, everyone gets excited and listens to what you are saying.
“Ten years ago, there were definitely many hurdles to cross in this regard. Today there are far fewer issues to overcome, both in terms of the equipment and the vessels.
“Of course, there is North Sea weather to deal with. It’s one thing doing an intervention offshore West Africa or in the US Gulf of Mexico (outwith the hurricane season), it’s quite another matter trying to do it here, whether with a rig or a vessel.
“The good news is that things are moving in the right direction – sure a bit slower than people were hoping for ten years ago, but we’re seeing intervention as a growth business; one that realises tangible value to the operators.
“A growing number of operators now plainly recognise that intervention does offer real value.”
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