It is no secret that strides have been made in completion and drilling efficiencies, leading to record production from shale plays. But low recovery rates show there is still room for improvement toward reaching each well’s full potential.

“If you have don’t have production it doesn’t matter how low the costs go. So we need to deliver some continuous improvement on both individual well and field performance,” John Cadenhead, strategy manager for unconventional reservoirs for Schlumberger, said during a technology panel presentation at the NAPE Business Conference in Houston.

While some gas wells in the US have a recovery factor of up to 45%, others – particularly wells targeting liquids – are not fairing so well. The factor is probably between 8% and 10%, Cadenhead said. Problematic areas include perforation issues, loss of fracture length, and sometimes wellbore connectivity.

After studies revealed that between 30% and 40% of all perforation clusters are unproductive and don’t add any value to the well, Schlumberger tackled the perforation issue by teaming with a consortium of companies. The task was to prove whether engineered completions and proper placement of perforation clusters could improve perforation efficiency. Each company was asked to log the lateral, allow Schlumberger to place the perforations, and run a production log afterward.

“We improved the efficiency by up to 82% of the perforation clusters in this group, which led to higher production and an average net present value gain of about US $1.5 million on an investment of around $100,000 per well,” Cadenhead said. Instead of placing the perforation clusters every 15 m (50 ft), 30 m (100 ft), or whatever the standard practice was for the well, the service company worked to understand differences across the lateral and reduce minimum pressure needed to create a fracture in the perforation cluster. “We look at the stress across the lateral, and we match perforation clusters in like-stressed rocks, so the differential is low (around 200 to 300 psi). … We are initiating more fracs in more clusters.”

While 82% of the engineered perforation clusters were producing, 64% were producing in the control group, he said.

Reservoir quality is another area getting attention. Using a well in the Eagle Ford shale play as an example, Cadenhead displayed a log and described how a dramatic drop in production was seen when crossing two sections of the formation despite having fraced the entire interval. “We’re still trying to understand why this is happening. … In the future, you will see technologies emerge that will attack this problem,” he said.

“Really the name of the game is increasing recovery,” Cadenhead continued, adding that refracturing is on the minds of many. But even that might not be as beneficial as some hope. “The trouble with refracturing is that typically the fracture that is producing takes all of the new fracture and you really don’t see a huge benefit, so you just refrac what is already producing well.”

Earlier this month, Schlumberger introduced its BroadBand Sequence fracturing technique, which uses a combination of fibers and multisized particles to improve wellbore coverage and reservoir contact. The technique allows users to frac the next perforation cluster or shut off those that are producing to stimulate perforations that had not been stimulated, Cadenhead explained.

A case study showed that Marathon Oil increased 115-day cumulative oil production per foot of lateral by 21% after applying the technique during plug-and-perf completions, according to Schlumberger. Another case study revealed BroadBand Sequence cut completion time by 46%.

“It’s not going to take bad rock and turn it into good rock,” Cadenhead said. “But it could certainly extend the life of the wells and make some of these one-third marginal wells perhaps more economic.”

Artificial lift and production surveillance also will be critical because shales decline rapidly, said Jim Raney, senior manager, engineering and technology, for Anadarko. Understanding flow dynamics in horizontal wells will be, too, along with surveillance and optimization.

“We go through three distinct artificial lift systems before we get to a plunger lifter adding energy to the bottom,” Raney said. One system lifts hydrocarbons for a certain amount of time, then reservoir performance changes and requires another lift system. “So the question is when do you do it? Which ones are economic?”

And how do you get the most from the reservoir and steer away from uneconomic wells? “Everyone is looking for the sweet spot,” Raney added.

Cadenhead put the technological state of the industry in perspective when he opened his presentation, referring to a 2000 quote from Intuit founder Scott Cook.

“We are still in the first few minutes of the first days of the Internet revolution,” he said. “We are still very early in the shale revolution, so we’ve got a lot to learn.”

Contact the author, Velda Addison, at vaddison@hartenergy.com.