Open-Hole Completion Innovations Push Efficiencies in Shales
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Home / 2015 / Open-hole completion innovations push efficiencies in shales
Open-Hole Completion Innovations Push
Efficiencies in Shales
in 2015, CurrentFeatures, Innovating While Drilling, May/June Apr 23, 2015 0
Longer laterals, rising stage counts drive uptake of open-hole systems in areas like Bakken, Granite
Wash
By Katie Mazerov, Contributing Editor
Designing an unconventional well these days is anything but simple. A decade of learning has uncovered a multitude of issues for operators to consider, from reservoir characteristics to stage counts. Thanks
to fast-evolving technological advances, operators also have multiple options. Cemented plug-and-perforation or an open-hole completion using ball-activated sleeves? Composite plugs or packers? Or, a hybrid
approach that combines the best of both worlds?
While cemented plug-and-perforation (P&P), which uses bridge plugs on wireline for isolation, remains by far the No. 1 completion technology worldwide for multistage stimulation, open-hole completions have
advanced at a fast pace over the past five years. This trend has been driven by longer laterals and the need for more stages. Ball- drop/sleeve fracturing techniques have improved significantly, breaking
through the early threshold of 10 or 15 stages to provide hydraulic fracturing capabilities for 50 or more stages with increased efficiency and reliability. Degradable alloys have further improved efficiency, the
latest trend being a dissolvable P&P system that can be applied in open holes.
“Operators in every major unconventional play are actively using, have tried or are considering some form of open-hole completion,” Beau Wright, Applications Engineering Manager for Baker Hughes, said.
“Some areas use the technique more than others, and we’ve seen shifts back and forth between P&P and open-hole methods. One system is not technically superior to the other, and these plays are not static
environments.”
Areas where open-hole systems are more common include the Bakken and Three Forks in North Dakota, the Granite Wash and Mississippi Lime. “Added efficiency for the longer laterals is a key driver, but in
some cases, the choice is as simple as operator preference or familiarity and comfort with one system or the other in a given formation,” Mr Wright said.
A cemented MP FracPoint system, introduced by Baker Hughes in 2014, is an alternative to
using packers for isolation in open-hole wells. The system enables perforation through clusters,
rather than a single entry point, to more effectively distribute the fracture treatment across a given
interval.
The need for efficiency is especially important in a market constrained by lower oil prices. “We are now in an economic environment where commodity prices have dropped so low that the fringe regions of
every play are uneconomic, regardless of how efficient we are,” John Cadenhead, Strategy Manager, Unconventional Resources for Schlumberger, said. “Operators can’t drill new wells that will pay out
over time, so they are selectively targeting core areas, or sweet spots, to reduce well costs and improve economics. The challenge is to maintain the efficiencies we have gained over time.”
Acknowledging that 30-40% of an unconventional well does not significantly contribute to production, Mr Cadenhead said operators more than ever must focus on the reservoirs they understand and the
stages they know will produce, eliminating the stages that won’t produce. “If we can reduce well completion costs by 30%, a well on the outside of the sweet spot becomes productive even at these low oil and
gas prices.”
The convergence of enhanced reservoir understanding – where to stimulate and why – and continued technological advances to overcome the mechanical limitations of stimulating longer laterals is the key to
optimizing efficiency, suggests Isaac Aviles, Global Portfolio Manager, Multistage Stimulation for Schlumberger. “The challenge we face is that the reservoir is driving longer and longer laterals with more
stages per foot.” Nowhere is this phenomenon more evident than in the Bakken, where laterals are now 10,000 ft or longer. The play has been pivotal to the evolution of open-hole completion technology.
Overcoming limitations
The Schlumberger Infinity degradable fracture ball and seat dissolve completely and
predictably, eliminating the need for milling and enabling full-bore production.
Open-hole completions technology relies on a graduated ball solution, with the smallest ball at the toe and largest at the heel, with open-hole packers for isolation. “The casing size physically restricts the
