Activities in developing tight oil and gas reservoirs, such as the Barnett shale and the Bakken formation, have grown tremendously in recent years. Economic production of these unconventional resources relies heavily on advanced completion technology such as horizontal wells with multi-stage hydraulic fracture stimulations.
Unlike single-stage fractured vertical wells, multi-stage fractured horizontal wells (MFHW) exhibit a unique flow regime, compound formation linear (CFL) flow, which consists of linear flow in the formation toward the collective hydraulic fractures after interference has occurred between neighboring fractures. This flow regime can easily be mistaken for a reservoir-boundary (or compartmentalization) effect in production analysis. Such a misinterpretation will result in incorrect reservoir property estimates and long-term production forecasts.
This paper applies log-log reciprocal rate derivative plots to identify and analyze flow regimes of MFHW wells producing under constant bottomhole pressure. It is observed that the CFL straight line slope in the reciprocal rate derivative plot depends on the ratio of fracture length over fracture spacing but is not sensitive to reservoir permeability. As a result, the CFL slope can be used to diagnose fracture stimulation effectiveness.