Rex Hjelm, a scientist at the New Mexico Consortium and Los Alamos National Laboratory, has new research findings that help us to understand how to maximize the production of natural gas. He just had his paper: Reduced methane recovery at high pressures due to methane trapping in shale nanopores, accepted to Nature, Communications Earth & Environment. The authors include Chelsea Neil, Mohamed Mehana, Rex Hjelm, Marilyn Hawley, Erik Watkins, Yimin Mao, Hari Viswanathan, Qinjun Kang, and Hongwu Xu.
In order to maximize the production of the natural resource, shale gas, it is important to understand the science behind hydrocarbon retention within the shale matrix. The prediction is that shale gas will exceed 3/4 of the total US gas production by 2050! And unfortunately, the current recovery rates are only about 20%.
In this research, the scientists looked at a new technique – integrating molecular simulation with high-pressure small-angle neutron scattering (SANS). This is an experimental technique that can characterize methane behavior in the field within shale nanopores at elevated pressures.
In this research, they found that increased pressure actually increases methane recovery from larger pores. The one thing to take into consideration is there is a trade-off with the trapping of dense, liquid like methane in the smaller shale nanopores. However, this is contrary to the current knowledge. These findings improve the understanding of confined fluid behavior during hydrolic fracturing, and have critical implications for maximizing hydrocarbon recovery.
To read the entire paper see: Reduced methane recovery at high pressures due to methane trapping in shale nanopores.
Figure above shows proposed mechanism for dense methane trapping in nanopores within the kerogen matrix. At higher pressures (6,000 psi), irreversible deformation of the kerogen matrix results in methane retention in pores even after pressure drawdown. See entire figure in the linked pdf.
Article by Carrie Talus