American Oil and Gas Reporter - September 2015 - 67

SpecialReport: Horizontal & Innovative Drilling
* Class 3, unconfined and non-stratigraphically-bound or out-of-zone natural
fractures.
Class 1 fractures encompass a region
where hydraulically induced fractures
constitute the dominant fracture type,
with natural fractures having little to no effect.
Class 2 denotes areas where stratigraphically bound fractures constitute a discernable portion of the SRV and interact constructively with induced fractures. Class
2 regions are prone to yield the best production results. This is attributed largely
to the increased fracture surface area attained either by hydraulically induced
fractures interacting with stratigraphically bound/confined natural fractures, or by
altering the stress regime (in favor of a low
stress bias) in structural environments
such as relay ramp structures to make the
rock matrix more susceptible to forming
complex fracture networks.
In contrast, class 3 regions are prone to
yield poor production performance. Non-

stratigraphically-bound fractures within a
given portion of the SRV result in negative production effects. Fracturing energy
is transferred through the fault displacement and diverted away from the target
zone, thereby leaving substantial amounts
of reservoir volume under- or unstimulated.
As the study explicitly suggests, not all
pre-existing structural geologic features are
created equal. Discerning their differences, occurrences and proportions within a given wellbore path and field is imperative to productivity. These learnings
are critical in delineating sweet spots, and
ultimately, optimizing full-field development planning in the La Salle County
field area.
❒

Editor's Note: For more detailed information on the results of the Eagle
Ford study, see URTeC 2148347, Investigating Natural Fracture Effects on Well
Productivity: Eagle Ford, La Salle County, Tx, a technical paper presented at the

2015 Unconventional Resources Technology Conference, held July 20-22 in San
Antonio.

PAOLO GROSSI is a geologist on
the Eagle Ford asset team at Talisman
Energy USA Inc., a part of Repsol.
Grossi is part of the multidisciplinary
team responsible for developing approximately 60,000 net acres of Talisman (Repsol)-operated Eagle Ford
assets in La Salle and McMullen counties, Tx. He began his career with Talisman Energy in Calgary in 2007,
and his professional focus has been on
the exploration, appraisal and development of unconventional resources,
including deep basin tight gas in Canada, as well as U.S. and international oil
and gas shale projects. Grossi holds a
B.S. in petroleum geology from the University of Calgary.

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SEPTEMBER 2015 67

American Oil and Gas Reporter - September 2015

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