Novel approach for production transient analysis of shale reservoirs using the drainage volume derivative

In this paper, we work directly with field production and pressure data to infer the drainage volume, and the instantaneous recovery ratio, defined as the ratio of the produced volume to the drainage volume. We also introduce a new w(τ) function that is related to a combined fracture and reservoir surface area. Our work draws upon the commonly used pressure transient and Rate Normalized Pressure (RNP) concepts. However, it specifically generalizes the concept of the drainage volume from PSS flow to transient flow, as is required for unconventional reservoirs, and then infers the underlying flow geometry to help differentiate and analyze different reservoir and fracture properties. The proposed formulation is applied to the analysis of the production data from shale oil reservoirs. The field data has been interpreted to describe the variations in performance characteristics seen in a number of wells.