Layered reservoirs with internal crossflow: a well-connected family of well-test pressure transient responses

This paper introduces a new explanation for "micro-cross-flow" response in transient well testing. This phenomenon which has been fully described for the first time by analytical, statistical and numerical techniques occurs in reservoirs with impaired connectivity in the lateral direction and no vertical communication. In the latter sense, these are commingled reservoirs, but the cross-flow occurs within the layers. This is reflected in the drawdown or build-up responses as a monotonic increase of the pressure derivative curves. The response might be misinterpreted as parallel-bounded flow (channels or faults) - but in the case study example, we demonstrate how the response can be generated in a meandering, point bar-dominated, fluvial reservoir with implications for fluvial reservoir modelling.