Seismic petrophysics and isotropic-anisotropic AVO methods for unconventional gas exploration

Exploration and drilling for natural gas in North America has moved radically away from conventional reservoirs to focus on unconventional reservoirs such as tight gas sands and shales. These reservoirs have low porosity and near-zero permeability with gas stored in natural fractures and within the matrix porosity. Economic gas production requires hydraulic fracture stimulation to open connections to existing natural fractures or matrix porosity, and successful stimulation depends on the formation's geomechanical brittleness being capable of supporting extensive induced fractures. However, despite adequate stimulation, significant variations exist between wells in expected ultimate recovery (EUR) due to the heterogeneity of these resource plays. Consequently, predicting natural fractures or fracture-prone “sweet spots” is essential to optimize development of such plays.