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RENZ
WELL
Production from the
Marcellus in its present form started when a deep,
vertical well (the Renz well) in Washington
County, failed to show any economic potential in 2004
(Fig. 6). The operator, Range Resources, pulled back to
the depth of the Marcellus and tested that interval with
a hydraulic fracture stimulation known in industry as a
‘massive slickwater frac.’
The difference between the
Renz fracture stimulation and the early Bradford
treatments is largely the number and height of fractures
required for economic payout. In the former case a rock
unit is split with many fractures through a thickness
200-300 feet whereas in the latter case only one
fracture in a sandstone layer a few feet thick is
required. Much larger quantities of water are required
for gas shale, hence the term, massive.
Slickwater contains an
additive similar to common dish soap so that massive
quantities of water can rush down wellbores without
being impeded by friction between the water and the
pipe. This technique was employed by Mitchell Energy in
the Fort Worth Basin of Texas to produce gas from
vertical wells in another gas shale, the Barnett, which
had many of the same characteristics as the Marcellus
gas shale.
Oil & Gas Fields of Pennsylvania (158KB image)
Initial production was so
successful following the Marcellus test in the vertical
Renz well that Range Resources moved quickly to
consolidate its land position in Washington County,
Pennsylvania and other places. By 2006, word of the Renz
success had leaked out to the point where other players
were seeking land positions in Pennsylvania. Following
the Devon Energy model of drilling horizontal wells in
the Barnett, Range Resources moved to form large enough
drainage units in Washington County to experiment with
the stimulation of horizontal wells during 2007. Range
Resources went public with the results of its first five
horizontal wells during an investor and analyst call on
December 10, 2007.
The Range Resources
announcement was unnoticed outside of industry experts
until it was interpreted for the public in a press
release issued by the Pennsylvania State University
(Penn State) on January 17, 2008. This press release
provided information that certified the Marcellus as a
bona fide super giant gas field. Calculations in the
press release were the outgrowth of over 30 years of
research on gas shale.
SOURCE:
Governor’s Marcellus Shale Advisory Commission
Commonwealth of Pennsylvania
7-22-2011 |
