Squeezing more out

06.01.2014
It would be possible to improve the overall recovery factor on the NCS from 50 to 60 per cent, according to Statoil. But that depends on whether such an effort can pay off.
  • Astri Sivertsen (text and photo)

Jannicke Nilsson and Kjetil Hove 
Purposeful.
Jannicke Nilsson and Kjetil Hove have key roles in improving recovery on the NCS.

 

Norway’s oil production has been in inexorable decline from its peak in 2001, despite the large additional discoveries made in subsequent years.

Nevertheless, Statoil’s ambition is to maintain output from the fields it operates on the NCS at today’s level of 1.3 million barrels of oil equivalent per day (boe/d) at least until 2020.

“New discoveries are important if we’re going to reach this target over the next few years,” says Kjetil Hove, vice president for North Sea east. “But recovery will also need to improve.”

Statoil defines improved oil recovery (IOR) as all planned activities and measures to get more oil and gas out of fields in a profitable manner than has been forecast at any given time.

Hove’s responsibilities include Oseberg and Troll, which have both won the IOR prize presented by the NPD in recognition of an extra commitment in this area.

Hydro received the award as Troll operator in 1998 for drilling horizontal wells to produce the thin oil zones in this field.

Statoil as operator won in 2012 for measures on Oseberg which included the adoption of gas injection to maintain production from the field.

When the company announced a year ago that it was aiming at a recovery factor of 60 per cent for the fields it operates, no timetable was specified for achieving this.

Whether and when it breaks the finishing tape will depend in part on the financial parameters and the price of oil and gas, says Jannicke Nilsson, senior vice president for technology.

Since its foundation, Statoil has boosted the recovery factor from 30 per cent to more than 50 on the NCS, and by one percentage point between 2011 and 2012 alone for the fields it operates.

The company reports that this single percentage point represented 327 million boe, worth more than NOK 200 billion at an oil price of USD 100 per barrel.

But both Hove and Nilsson emphasise that economics represent the big stumbling block when seeking to improve recovery even further.

 

Methods

“We can certainly find methods from a technological and reservoir perspective which make it possible to achieve this,” says Hove. “Reaching the final barrels profitably will be the big challenge.”

Oil prices are also an important factor, Nilsson adds. If they fall to USD 60 per barrel, recovering 60 per cent of the reserves will be impossible. Costs cannot be cut enough to compensate.

“The tax regime plays a key role, too,” she says. “Amendments to the rules announced earlier this year were unquestionably unfavourable for IOR. Many projects will not be as profitable as they perhaps were two years ago.”

Getting more wells drilled faster on the older fields is essential for extracting their final reserves and extending their producing life, Nilsson points out.

So cost cuts are one of the three most important measures she and Hove identify when asked how Statoil is to reach its IOR target.

This calls for more rigs, enhanced efficiency on both fixed and floating facilities, extracting more from each well and drilling more cheaply.

Expanding rig capacity has been the premier IOR measure, and Statoil has made substantial investments in new units and upgrading old drilling facilities.

The second approach involves achieving more intelligent and advanced wells through the development and testing of new technology. And cost cuts are the third, as noted above.

 

Initiative

Drilling and wells account for the biggest expenditure in petroleum production, so Statoil has launched an initiative to bring down costs in that area by 25 per cent.

Launched six months ago, this goal is to be reached by 2015 – primarily through simplification and standardisation.

Subsea technology currently provides an example of overly expensive solutions, says Nilsson. “We must help our suppliers to minimise tailor-made products.

“They must come up instead with standard answers so that we can get good solutions while keeping down prices. We must think simplification to cut the time taken. Simpler subsea solutions could contribute to improved recovery on many fields.”

Statoil recently reviewed its technology strategy, she reports, and has changed its priorities with regard to subsea facilities.

The company will concentrate in future on technical solutions which can help to get more out of fields currently in production rather than on what it thinks may be needed 15-20 years ahead.

A great deal of work is moreover being devoted to understanding the sub-surface better by developing the mapping and modelling tools used on the fields.

Statoil will be opening a large new IOR centre in Trondheim next spring. Costing NOK 240 million, this will include an industrial computerised tomography (CT) scanner.

A hundred times more powerful than a corresponding medical machine, the latter is intended precisely to enhance knowledge of reservoir change.

“Good mapping of the sub-surface is crucial for all IOR projects,” explains Hove. “Fourdimensional seismic on Troll and Oseberg, for example, has allowed us to optimise well positions.”

Nilsson says that Statoil intends to adopt less traditional recovery methods – such as adding chemicals to injection water and similar approaches, often called enhanced oil recovery (EOR).

“We’re currently using a great deal of produced water for injection, but other types of water could permit substantially greater utilisation of the reservoirs,” she explains.

Statoil is cooperating with universities worldwide to explore such opportunities, and resolved this autumn to do more research on polymer flooding.

That technique has a great potential both on the NCS and internationally, as noted in the article entitled “Thicker than water” on page 25.

Nilsson emphasises that EOR is a small part of Statoil’s IOR package, accounting for only three per cent of the additional resources it hopes to secure from all improved recovery measures.

 

Pilots

The company runs 60-70 pilot projects every year on new technology and methods. Some are halted before being implemented, while others continue. This can be a time-consuming process.

Statoil began research on subsea compression in the early 1990s, for example, but a plan for development and operation of such a system on Åsgard in the Norwegian Sea was only submitted in August 2012.

Much of the job involves deciding which tools are to be used and where, and the company is currently introducing a new internal method for this work.

It takes the form of a database of all existing types of equipment and technical solutions, providing a systematic overview in place of information which may be hidden away on local drives.

Statoil establishes a task force of experienced specialists for new development projects which can assess the challenges faced and propose technology to optimise recovery from the reservoirs.

A recent example of this approach is provided with what will be the "Johan Sverdrup" development operated by the company in the North Sea.

“These specialists are highly experienced personnel who do not belong to the project team, but who can identify the challenges and the technology to overcome them,” says Nilsson.

The "Johan Sverdrup" task force has already come up with several technologies which could be used on the field, including ones Statoil has not used before.

 

Plan

New approaches have also been adopted on existing producers, and Hove reports that an IOR plan is drawn up for every field operated by Statoil during the annual well planning process.

“The whole industry depends on keeping alive what we’ve got on the NCS,” Nilsson adds. “To be able to tie in new discoveries, it’s important that all the transport pipelines are good quality. A whole infrastructure can’t be based on small developments.”

Although no schedule has been set for reaching the 60 per cent target, this must clearly be achieved within the producing life of the existing facilities, Hove emphasises.

“This isn’t a matter of a century, or of a decade. It’s somewhere or the other between them,” he notes.