Characterization of Multi-Scale Discrete Fracture Network Systems in Unconventional Reservoirs Using Dynamic Data

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Development of unconventional tight or shale reservoirs has received much attention in recent years because of the large resource estimates worldwide. Horizontal wells with multi-stage hydraulic fracturing are drilled to enhance reservoir contact area and to achieve economic production rates. This stimulation technique is particularly efficient if hydraulic fractures can connect to sweet spots due to the presence of existing fractures. A tight/shale reservoir can be conceptualized as a dual-medium with two distinct sub-systems: matrix and fracture. The time scales for flow in the two systems differ significantly due to the high contrast in their permeability. The matrix has a very low in-situ permeability, while the fracture is a local discontinuity with a very high permeability. Fractures can be large and localized around the wellbore (e.g., hydraulic fractures) or small and located away from the stimulated zone (e.g., micro fractures). It should be noted that this proposal focuses on in-situ development of shale/tight oil/gas reservoirs, while surface mining of oil shale is not considered.