Understanding hydraulic fracturing: a multi-scale problem.
Despite the impact that hydraulic fracturing has had on the energy sector, the physical mechanisms that control its efficiency and environmental impacts remain poorly understood in part because the length scales involved range from nanometres to kilometres. We characterize flow and transport in shale formations across and between these scales using integrated computational, theoretical and experimental efforts/methods. At the field scale, we use discrete fracture network modelling to simulate production of a hydraulically fractured well from a fracture network that is based on the site characterization of a shale gas reservoir. At the core scale, we use triaxial fracture experiments and a finite-discrete element model to study dynamic fracture/crack propagation in low permeability shale. We use lattice Boltzmann pore-scale simulations and microfluidic experiments in both synthetic and shale rock micromodels to study pore-scale flow and transport phenomena, including multi-phase flow and fluids mixing. A mechanistic description and integration of these multiple scales is required for accurate predictions of production and the eventual optimization of hydrocarbon extraction from unconventional reservoirs. Finally, we discuss the potential of CO2 as an alternative working fluid, both in fracturing and re-stimulating activities, beyond its environmental advantages.This article is part of the themed issue 'Energy and the subsurface'.
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
J D
JD
Hyman
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
J
J
Jiménez-Martínez
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA viswana@lanl.gov.
H S
HS
Viswanathan
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
J W
JW
Carey
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
M L
ML
Porter
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
E
E
Rougier
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
S
S
Karra
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
Q
Q
Kang
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
L
L
Frash
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
L
L
Chen
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
Z
Z
Lei
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
D
D
O'Malley
Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA.
N
N
Makedonska
discrete fracture network; hydraulic fracturing; lattice Boltzmann; microfluidics; shale gas; subsurface flow and transport