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gaining acceptance in the Gulf of Mexico. you can go behind a rig to tidy up wells, Brazil and in the Gulf of Mexico. So far it Deepwater opportunities

SubseaEyebrow

Contractors and service providers are do testing or pick up intervention, you “Shell has a long history of using RWLI has performed subsea well intervention joining forces, eying new areas to intro- can save rig days and money. Most reports techniques,” says Buchan, co-chair of operations on wells at 3800ft off Nigeria duce their technologies and operators you read predict double-digit compound this year’s Deepwater Intervention Forum and to 6200ft off Brazil. The current are pushing the boundaries of RLWI into annual growth rate in the intervention conference, organized by OE and held industry record is 8100ft, Buchan says. deeper waters. space over the next 3-5 years.” in Galveston. “In up to about 1000ft “We are going through a learning curve water depth, it is established technology. as an industry on how to maintain an

Why riserless? Dominating the market

Beyond 1000ft, there are some technol- effective seal in these water depths. It is

Riserless light well interventions are To date, Norway and the UK North ogy concerns within the operator com- coming, slowly,” Buchan says.

performed to address well integrity issues Sea have been a front runner in RLWI, munity as to reliability and environmen- Offshore Nigeria, Shell developed a and maintain or enhance well production due to the fact it has the most mature tal protection.” system which could be mobilized on a without using a riser, by deploying inter- subsea trees in the world, Neumann Some of the concerns are around the vessel of opportunity. Instead of using vention tools into the well on wireline, says, with dedicated riserless light well ability to isolate the well from the sur- a conventional rig, with an integrated electric-line and slickline using a subsea intervention vessels established in both rounding environment on the seabed. “It subsea lubricator system, the frm used a intervention lubricator. A range of activi- basins. “Operators are now so familiar is a dynamic seal which you are running lower riser package, emergency discon- ties can be performed, from acquiring with RLWI they even have a vision all a conduit wireline or slickline through nect package and a pressure control head production data and running integrity logs intervention will be done riserless in and that has to isolate the well fuids – effectively a workover riser system to retroftting gas lift valves and perform- the future. That is their target because it from the environment,” ing scale squeezes. Riserless stimulation, is more cost effective. It is a technology Buchan says.

or high-rate pumping for fracturing, is also proven over the years to be reliable, safer Using a riser-based being used to improve production. and more effcient,” he says. intervention system, the “Over a period of time, reservoir condi- BP has had a dedicated well inter- seal is on the rig foor. On tions change, such as producing more vention campaign west of Shetland on the seabed, the seal has to water or you might want to set plugs the UK Continental Shelf, under a long be able to deal with the to re-perforate,” says John Thomson, term alliance led by Island Offshore hydrostatic pressure. The intervention engineer, Global Wells (with Oceaneering, FMC Technologies scenario when the hydro-

Organization, BP, based in Aberdeen. and Altus Intervention) using the Island static pressure is greater

For subsea wells, Constructor, since 2009, as well as than the well pressure cre- the need for interven- operations on its other North Sea assets ates additional demands tions is greater and with Helix Energy Solutions, using the on the sealing mechanism, will become more so Seawell, Well Enhancer and Skandi which means proving a as wells become more Constructor. The frm has 197 subsea reliable pressure control signifcant-sized wells on the UKCS, the deepest in about system is crucial. producers in deeper 500m water depth, west of Shetland, It’s an area Shell is water. Subsea wells, where the weather window spans just working on closely, along- which, due to fewer April to mid-September. side technology vendors. planned interventions John Thomson, intervention engineer, Shell is keen to have the typically have a much lower recovery fac- Global Wells Organization, BP, based in technology ready to work tor than dry tree wells, actually require Aberdeen, says the long-term contracts on its subsea well stock, even more attention, says Henning Berg, have meant continuous improvements which includes deepwa-

An emergency disconnect package and lower riser

President, Subsea Services, OneSubsea. have been made, both around manag- ter wells offshore Nigeria, package. Image from OneSubsea.

Using RLWI, opera- ing the challenging weather conditions tors can reduce vessel west of Shetland [OE: January 2015] and costs and perform operationally. In 2007, BP performed one more interventions. subsea well intervention operation in

You can operate on the North Sea a year. It is now about 12, 20-30 wells a year in that short season, says Thomson, and using RLWI, says they’re delivered on time and on budget.

Bjarne Neumann, “The North Sea is not a challenge any director of well more [for RWLI], it is becoming routine” intervention services he says. at FMC Technologies, compared to 10-15 Colin Buchan, Wells Engineering per year using riser-based operations. Manager Subsea Well Intervention at

Furthermore, money spent on inter- Shell, says Shell frst used RWLI in the vention brings greater return than cash North Sea in 1994. Since then the tech- spent on greenfeld projects, says Carl nology has been used more and more in

Roemmele, Well Access Lead at GE Oil & the North Sea and now in the deepwater

Gas. “This is why we are seeing the big basins in the US Gulf of Mexico, Brazil drive into monohull deployment,” he and West Africa. However, to be fully says. “Monohulls are a quarter to a third adopted in deepwater, technology, vessel of the cost of a drill rig, depending on capabilities and economic viability need

Q7000

Helix Energy Solutions’ semisubmersible well intervention vessel.

Image from Helix Energy Solutions. what you get on it and the water depth. If to be addressed. oedigital.com April 2015 | OE 55 054_OE0415_Subsea_RWLI.indd 55 3/23/15 6:18 PM