Improved oil recovery even amid giant discoveries

Norwegian petroleum company Statoil recently discovered an oil find that could lead to one of the largest field developments on the Norwegian Continental Shelf. Still, it is as important as ever to make sure companies extract the last remaining reserves from existing petroleum fields, says the Norwegian Petroleum Directorate.

It was August 27, on the eve of the Offshore Northern Sea Conference in Stavanger, Norway, a proud Statoil announced a new oil discovery on Utsira High in the North Sea had been found together with partners Petoro, Det norske oljeselskap and Lundin. The Geitungen prospect 16/2-12 proved between 140 and 270 million barrels of recoverable oil equivalents, marking a new discovery in the highly promising Johan Sverdrup area.


Johan Sverdrup, which currently comprises two discoveries, is already regarded as one of the largest discoveries on the Norwegian shelf since the mid eighties. If there is communication between Johan Sverdrup and Geitungen as well data currently shows, Johan Sverdrup could have its current reserve estimate of 900 million to 1.5 billion barrels upgraded evenfurther.

 

Gas Injection
The Norwegian Petroleum Directorate (NPD) however wants oil companies to still keep their focus on improving oil recovery even further. Despite the renewed confidence in the Norwegian shelf with this new North Sea discovery, as well as other recent giant finds in the Barents Sea, the NPD believes it is essential that all profitable resources from existing fields are produced.


One of the ways to improve oil recovery is gas injection, both using a field’s own associated gas and gas from other fields. This method of maintaining pressure in the reservoirs and extracting more oil has been used on the Norwegian shelf since 1975 on the Ekofisk field. Gas injection helped lift the oil recovery rate at Ekofisk from 17-18% to more than 50%, according to the NPD. Since then, gas has been injected on a total of 28 Norwegian fields.


“We estimate that, overall, Norway extracts about 2.2 billion barrels more oil from the fields than would be the case without gas injection,” said Bente Nyland, NPD director general, in her IOR (Improved Oil Recovery) Award 2012 speech at the ONS conference. “This volume is greater than the expected oil resources of the entire Johan Sverdrup field.”

 

Core sample from Geitungen, the latest oil discovery on the Norwegian shelf. © Statoil.

 

IOR Award to Statoil
The NPD picked Statoil’s sub-surface team to receive the IOR prize this year for its subsea work at the Oseberg field, where gas injection has yielded about 400 million barrels of additional oil from the field that would have been the case with just water injection. This is the first time the NPD awards the IOR prize to gas injection since the award was first established in 1998.

“These days, with high oil prices and relatively low gas prices, further use of gas injection is relevant for both operating fields and upcoming field developments,” said Nyland. “Both courage and determination were needed to implement the TOGI (Troll Oseberg Gas Injection) project – not least because the development was already approved with water injection. This meant that Oseberg had to be considered again in the Norwegian Parliament.”

The TOGI project was considered both revolutionary and controversial at that time in the late 1980s, according to Statoil. It used a remotely controlled subsea installation – the first of its kind in the world. Oseberg was also the first field where gas injection was approved as the main method to recover oil -- both injection of its own gas and imported gas from the Troll field -- where the subsea template TOGI was utilized. Since TOGI came on stream in 1991, up until 2002, Statoil has injected 21.7 billion standard cubic metres of gas into Oseberg. The company received approval last year for extended gas injection and plans to defer its increase in gas exports from 2017 to 2020, which will help increase recovery even further. The main field currently exports about two billion standard cubic metres, though most of the gas will be produced and sold after 2020.

“The sub-surface specialists on Oseberg are the epitome of a team that has worked long and systematically on IOR to produce some fantastic results,” said Øystein Michelsen, Statoil executive vice president, development & production Norway. “IOR is all about thinking long term and holistically, and since we submitted our (plan for development and operation) for Oseberg in the 1980s, we’ve doubled the reserves on the field.”

 

Past Decade of IOR Winners
The list of past winners of the NPD’s IOR award includes a number of Norwegian and international companies and academia:


2001 Statoil and Egil Sunde for the use of bacteria, MEOR, in the Norne field
2002 No worthy candidate found
2003 BP for “Life of Field Seismic” project in the Valhall field
2004 Gullfaks license for project decisions and implementation ranging from advanced drilling into new reservoirs to new methods of produced water treatment.
2005 Arne Skauge, Prof at Univeristy in Bergen/CIPR, for his success in bringing IOR research from laboratories to pilot testing educational skills.
2006 Halliburton and Baker for developing well technology needed in the Troll field.
2007 Talisman for courage and willingness to operate fields at tail end to prolong the
production – especially mentioned Yme field redevelopment.
2008 No worthy candidate found.
2009 FMC Technologies for having demonstrated the courage and determination to invest in technology that increases production from seabed wells.
2010 Professor Tor Austad (University of Stavanger) and the Corec research centre at IRIS for the research carried out to improve oil recovery from chalk fields.

Associated companies:


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