SHALE GAS: OPPORTUNITIES AND CHALLENGES (Invited Presentation)

The production of hydrocarbon fluids from very low permeability rocks has been increasing at a high rate for many years, but it received little attention until production reached about 20% of US total gas production, just a few years ago, and resource reassessments indicated that addition of “first generation” unconventional gas (shale gas, tight gas and coalbed methane) could double the US technically recoverable resource. Shale gas is the most important of these resources, and by 2035 it could account for almost ½ of US natural gas production. Shale gas production is enabled by horizontal drilling, hydraulic fracturing and fracture propping, but despite many innovations, recovery factors are low (for shale gas recovery factors vary greatly with an average of about 20%). Based on current technology and resource estimates, hundreds of thousands of hydraulically fractured wells will be required to produce the US shale gas resource, and millions will be required worldwide. We have developed physics-based numerical models for hydraulic fracturing, fracture propping, the placement of propping particles in fracture apertures and fluid flow in propped fractures, and applied them to shale gas recovery. Most of these models are based on the discrete element models for rock deformation and fracturing coupled with a Darcy flow or pore network model for fluid flow and a continuum heat transport model.

US and global first generation natural gas resources will be discussed and an overview of the technology used to produce gas from these resources will be presented with a focus on the geomechanics of shale gas production and the challenges of producing hydrocarbon fluids from very low permeability rocks. Some of our own research results will be included in the presentation.