If you can learn how to coax out more years from your infrastructure, look with fresh eyes at well data and think laterally, then you can gain a competitive edge when working with mature assets.
Maersk Oil is an old hand in the art of teasing out oil from aging fields in the North Sea and the case of the Gorm field, in the Danish North Sea, is just one example of how it is done.
Almost three decades after the field came onstream, a routine check showed that one well had leaks that could compromise safety. It was shut immediately and, facing a loss of 2,000 barrels per day from just one well, engineers had to decide fast – to abandon the well or drill it again.
After investigating further and reviewing well log data the team came up with a hypothesis – that the well had never produced from a reservoir section and that redrilling a new well in parallel to the original one could actually tap it.
The result was a little surprising. Although the team suspected that parts of the reservoir had remained undrained by the well, once its twin set to work, production doubled to 4,000 barrels per day.
“What I learnt from this experience is – know your wells. Do your reservoir surveillance, well tests and reservoir modeling,” said Per Bak, Section Head in Petroleum Engineering. “It sounds pedantic. People say: ‘You don’t make oil from data’. Well, this shows you can.”
The difficulty in the operation was drilling through sand fractures stemming from the original well. Deep underground it is hard to tell where those sand fractures end up a hundred or more metres away from their points of origin.
“Understanding where sand fracs are has become high priority because this is a big challenge in our maturing fields. We have incorporated a number of logging tools measuring electrical resistance and atom density so that we are not just playing a guessing game,” Bak said.
As another consequence, Maersk Oil established a multi-disciplinary team that looks at workover wells to see how additional benefits can be gained.
“You need to stand on a good foundation of reservoir knowledge and make the most out of these challenges by turning them into opportunities,” Bak said. “What I have learnt is the importance of being ready – when the next well goes, I will be there for it.”
Source:Maersk Oil, January 12, 2011;