Fracture porosity is associat-ed with high permeability and dominates reservoir flow capacity. Fracture porosity is the focus of most explo-ration efforts. Natural high-angle fractures have been observed in nearly all cores. There is a short term production kick, followed by a long, slow decline. In contrast, matrix porosity in Devonian shales is asso-ciated with very low permeability.
Porosity is present only as micropores associated with microfractures.
Decline curves typically include an initial steep region as fractures produce and a long low decline as the matrix desorbs gas. Most production wells in Devonian gas shales are vertical. Horizontal wells have been tried several times, but have not clearly been better. It is possible that the horizontal leg of Devonian shale wells has been too short. Exploration strategies include mapping areas of thick black shale, areas of peak hydrocarbon generation, mapping fracture intensity, as well as drilling near good wells.