"Schlumberger’s Cordes added that some wells perform better after refracking than their original IP rates."
Oil and service companies are starting to view the shale proposition in a more integrated fashion. While efforts in the past have focused on drilling the wells as quickly as possible, now effective completions are taking center stage.
Mo Cordes, vice president of integration at Schlumberger, said that studies on perforation effectiveness have provided some sobering results. “We started looking at all of the different shale plays across North America, and one thing we found was that a large part of the lateral was not producing,” Cordes said. “We ran a number of production logs in these laterals and found that 40% of the perf clusters were not contributing to production.”
This discovery prompted the company to examine new ways of ensuring more productive completions. “There’s really not one silver bullet,” he said. “It’s a series of workflows and technologies that are starting to unlock the full potential of these plays and improve the productivity.” He added that some areas are seeing up to 40% improvement in production.
“We’ve moved away from the cookie-cutter approach to optimizing the completion along the lateral to ensure we improve the productivity,” he said. “We’re seeing 80% and in some cases close to 100% contribution of the lateral when we put this process together.”
Baker Hughes recently launched its NextWave service to maximize value from the existing wells in unconventional reservoirs.
“The first wave isn’t over yet,” said Sergey Kotov, manager of integrated technology for Baker Hughes. “The difference is that going forward we need to change our approach to unconventional reservoir development to one that is more strategic. The first wave focused more on wells and cost efficiencies rather than long-term production and ultimate recovery.”
He added that past approaches led to inconsistent results. “This could be justified when oil prices were $100/bbl, but even then it was unacceptable,” he said. “Now it has become more critical.”
Increasingly, operators are turning to refracturing to optimize their completions. The service covers a broad spectrum of solutions and offers a comprehensive approach to rejuvenating existing underperforming wells.
Candidates are screened through a review of production data, reservoir quality and initial completion and then diagnosed. Next a rejuvenation program is designed, and economic analysis is performed. This leads to a detailed operational plan.
Different wells will require different treatments. Some might benefit from cleanouts, chemical treatments and installation of artificial lift systems, while others might require mechanical isolation and restimulation.
Refracking
Costs might have come down somewhat, but it’s still an expensive proposition to drill a shale well. Kotov said that well rejuvenation costs a fraction of the cost of a new well.
“It’s a faster payback and provides increased bookable reserves since we’re adding reserves by accessing more reservoir and changing the decline curve,” he said. There is also lower HSE risk because the infrastructure is already in place, he said.
Not every well makes a superb refracking candidate, however. “When the industry started doing refracks in shales, the results were very diverse from play to play and from well to well,” he said. “We needed to understand the reservoir and use a holistic approach to identify the candidates.”
Cordes said that having a wide variety of technologies helps to optimize these plays.
For instance, Schlumberger applies its HiWAY flow-channel fracturing technique to increase fracture conductivity, and it uses its BroadBand Sequence fracturing service during refracturing to improve production. “It’s one of the best diverting agents,” he said. “That allows refracturing to work.”
A study recently conducted by Baker Hughes indicated an average EUR increase of 53% in the Eagle Ford Shale and 69% in the Bakken.
Schlumberger’s Cordes added that some wells perform better after refracking than their original IP rates.
http://www.epmag.com/technology-boosts-returns-shales-800891#p=full
