Recent advances in the analysis of production data suggest that in shale reservoirs, a horizontal well with multiple hydraulic fractures creates a Stimulated Reservoir Volume (SRV). This SRV consists of matrix and fissures similar to a naturally-fractured system. Traditionally, dual porosity reservoir models have been used to describe the behavior of naturally-fractured reservoirs, and therefore these models can also be used to analyze the gas production from the SRV of shale reservoirs.

Often linear flow is the dominant flow regime in these reservoirs, and because of the low permeability, production takes place at high drawdowns (effectively constant wellbore flowing pressure). Accordingly, in this work, we develop typecurves for linear flow, constant flowing pressure, and transient dual porosity. First, we identify the different types of linear flow that may be seen in transient matrix-to-fissure interporosity flow, in the presence of a fully penetrating hydraulic fracture. Second, we provide practical criteria to differentiate between the types of linear flow. This allows us to determine if the reservoir can be treated as an equivalent homogeneous reservoir or if it should be treated as a dual porosity system.

In the paper, we generate dual porosity typecurves for various Lambda and Omega values, and convert them to a single curve that is equivalent to Wattenbarger's linear flow typecurve. We propose a work flow using this single curve, and we identify if and when it is possible to uniquely evaluate reservoir properties such as effective permeability and areal extent of the fissured system (SRV).

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