LNG supply solution
To ensure 100% fleet utilisation, Antero Resources knew it
would need a source of natural gas when field gas was either
unavailable or not suitable for the GE-Waukesha engines. The
company completed some trials with propane but found the
engine de-rating was large and unacceptable. Compressed
natural gas (CNG) was evaluated, but was quickly eliminated
when compared to LNG for two major reasons.
First, the logistical challenge of supplying three to four
times the number of fuel deliveries and resultant higher risk to
reliable fuel supply was deemed far too significant, not to
mention the additional truck traffic and noise pollution. The
lack of fuel supply and a resulting rig ‘blackout’ to a 100% gas
rig, especially when the rig is in horizontal drilling mode, could
result in loss of wellbore integrity which can wipe out a years’
worth of fuel savings in a single incident. Second, to provide
the same amount of on-site fuel, Antero would need three to
four times the area on the pad. This was not possible,
especially given the Appalachia terrain (see Figure 2).
Therefore, it was determined that LNG was the best
solution to ensure that the rigs could burn natural gas 100% of
the time. LNG and field gas have worked extremely well
together, achieving the following outcomes:
Fuel savings of approximately US$ 2000 - US$ 6000 per
day have been delivered vs. diesel fuel when operating on
LNG and wellhead gas respectively, with an average 50/50
split between wellhead field gas and LNG.
When utilised together as a total solution, field gas and
LNG provide fuel in the range of US$ 1.50 to US$ 2 per
diesel gallon equivalent (DGE), significantly below the cost
of diesel over the past five years.
100% LNG supply reliability performance and operation of
the LNG on-site storage and regasification system with an
on-stream factor in excess of 99.5%; as a result, Antero has
never had its wellbore integrity impacted by a gas-fuelling
problem.
Flexibility of mobile LNG storage and vaporisation units
enables Antero to develop a leading production position in
the Appalachian Shale Basin and quickly deploy rigs to new
areas where field gas fuel is not readily available.
Figure 2.
On-site LNG transport trailer and LNG storage/regas
trailer. (Source: Antero Resources and Prometheus Energy.)
