American Oil and Gas Reporter - August 2015 - 56

SpecialReport: Horizontal Well Operations

Encana Corporation began
testing the economics of refracturing in northern Louisiana's Haynesville Shale last
year. The nine wells it refractured are in the Creedence and
Bolan fields, which are located
mostly in De Soto and Red
River parishes, respectively,
and were completed with the
wider cluster spacings and
smaller stimulation volumes
with which Encana began its
Haynesville operations.

Technical Selection
CONSOL has identified 22 additional
refrac candidates for the next 18 months,
and Passman says the company is evaluating
a couple hundred more. She says the company selects candidate wells for refracturing
by asking three critical questions:
* Is the well on decline?
* Can the completion be improved?
* Can the reservoir handle a refrac?
To answer those questions, Passman
says CONSOL relies on modeling and
analysis. "I am a huge fan of multivariate
and probabilistic analyses of performance
data," she reveals.
Passman says CONSOL's team also
runs fracture and hydraulic models, looking
at the near-wellbore area. These petrophysical models project proppant loading,
water volumes and sand placement. "Modeling is key to understanding what we
think can be done versus what actually
happens," Passman says.
She adds that it is crucial that the
team understand how adding perforations
will affect the wellbore and current production. "When we pump high volumes
of proppant, it is really important to understand the stress created," Passman explains. "We do not want to collapse old
propped fractures or embed the proppant.
Our goal is to tap into new reserves."
By changing how it pumps, the chemicals used and the proppant deployed,
Passman says CONSOL is creating more
complexity near the wellbore and con56 THE AMERICAN OIL & GAS REPORTER

necting more pore spaces. "We expect to
recover more gas, upping the expected
EURs of those wellbores," she affirms.
Passman says she also expects to gain
insight into new completions through
CONSOL's refracturing activity. "Our
early completion data are not useful for
modern completions, but the data from
refracturing are directly relevant," she
says. "These data let us get closer to optimizing our new areas, which is a significant benefit."

Economic Justification
At the end of the day, it is all about
profit margins, lowering capital expenditures while increasing production, and
optimization, notes Passman. It is one
thing to find a refrac candidate; it is
another to confirm it makes economic
sense. She says every candidate that passes
CONSOL's technical evaluation also must
make sense from both net present value
and portfolio management perspectives.
"We have to decide whether the incremental reserves are worth taking the
wellbore and adjacent wellbores off line
for a few weeks," Passman says, explaining that production must be halted to
avoid interference.
"In most cases, the NPV has been
great and the rate of return has been very
strong as well, although not as strong as
a whole new wellbore," she evaluates.
Refracturing has to be weighed in the
context of a company's overall development

program, Passman reasons. "In this market,
we are going after our fastest rate of return
and best producers first," she says.
Passman says CONSOL looks for opportunities to take advantage of the stacked
nature of Pennsylvania plays. The company
is working in the Burkett and Utica formations in addition to the Marcellus. "If
we can do a refrac at the same time we
are drilling new wells in an area, the economics are easier to justify," she points
out, confirming that there is a cost advantage to simultaneous operations and a potential benefit in avoiding a fracture hit.
"In areas where we want to go back
and get the Burkett in the future, we can
refracture our Marcellus wellbore to create
stress shadowing to contain the new fracture in the Upper Devonian as well,"
Passman details.
She says CONSOL also sees the opportunity to refracture a Marcellus well
when it drills a Utica well nearby. That
way, she says, the company realizes increased production and reserves from
both wells at a lower cost than if they
had been completed separately. "The
stacked play environment gives us a real
win-win situation," she says.

Increase Understanding
Encana Corporation has been experimenting with refracs in the Eagle Ford
as well as in North Louisiana's Haynesville
Shale.
Says Mike McAllister, executive vice
president and chief operating officer, "We
have seen good early results from our refractured Eagle Ford wells, and completed
our third refrac (earlier this summer).
"We are trying to increase our understanding of how much of the well actually
is being restimulated," McAllister outlines.
"Our data to date suggest we are reaching
only a small portion of the wellbore. So,
while we have identified about 100 wells
that are potential candidates for refracturing, we are taking a deliberate approach.
The technology needs to advance before
we push this to scale."
In the Haynesville, meanwhile, Will
Hunter, a completions engineer for Encana,
says the company has been testing the
economics of refracturing in Red River
and De Soto parishes, La. The company
performed nine refracs last year. He says
the results from those wells and the lessons
learned from the process are helping engineers plan for the next round of tests.
For the initial Haynesville refracs,
Hunter says Encana targeted older, un-

American Oil and Gas Reporter - August 2015

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