Refracturing technology for horizontal wells in Niudong volcanic reservoir of Tuha Oilfield

To address the challenges of rapid production decline and low recovery in horizontal wells after volumetric fracturing in Niudong volcanic unconventional reservoirs of Tuha Oilfield, this study innovatively proposes a multi-stage diversion re-fracturing technology integrating "subdivided perforation + pre-fracturing energy replenishment + enlarged stimulated reservoir volume", along with precise staged re-fracturing techniques. Systematic research on energy storage mechanisms and reservoir fracability evaluation has optimized key parameters including energy-carrying media, injection volume, diversion stages, and diverter particle size distribution. A comprehensive technical system was established, incorporating well/interval selection criteria, subdivided perforation, pre-fracturing energy injection, full-well multi-stage diversion, and precise staged re-fracturing. Field tests during 2023—2024 on 15 wells in Niudong Block achieved 100% operational success with 86.7% effectiveness, delivering average incremental production of 4.7 t/d per well (cumulative 832 t) and an attractive input-output ratio of 1.18. This successful practice provides a replicable technical template and valuable field experience for enhancing production and recovery in underperforming horizontal wells of Tuha Oilfield’s unconventional reservoirs.