Observations
of the Release of Non-methane Hydrocarbons
from Fractured Shale
- Publication date
- Publisher
Abstract
The organic content of shale has
become of commercial interest
as a source of hydrocarbons, owing to the development of hydraulic
fracturing (“fracking”). While the main focus is on
the extraction of methane, shale also contains significant amounts
of non-methane hydrocarbons (NMHCs). We describe the first real-time
observations of the release of NMHCs from a fractured shale. Samples
from the Bowland-Hodder formation (England) were analyzed under different
conditions using mass spectrometry, with the objective of understanding
the dynamic process of gas release upon fracturing of the shale. A
wide range of NMHCs (alkanes, cycloalkanes, aromatics, and bicyclic
hydrocarbons) are released at parts per million or parts per billion
level with temperature- and humidity-dependent release rates, which
can be rationalized in terms of the physicochemical characteristics
of different hydrocarbon classes. Our results indicate that higher
energy inputs (i.e., temperatures) significantly increase the amount
of NMHCs released from shale, while humidity tends to suppress it;
additionally, a large fraction of the gas is released within the first
hour after the shale has been fractured. These findings suggest that
other hydrocarbons of commercial interest may be extracted from shale
and open the possibility to optimize the “fracking”
process, improving gas yields and reducing environmental impacts
