Revitalizing a mature oil play: Strategies for finding and producing unrecovered oil in Frio Fluvial-Deltaic reservoirs of South Texas. Annual report, October 1992--October 1993

Abstract

The Frio Fluvial-Deltaic Sandstone (Vicksburg Fault Zone) oil play of South Texas has produced nearly 1 Bbbl of oil, yet still contains about 1.6 Bbbl of unrecovered mobile oil and nearly the same amount of residual oil resources. More than half of the reservoirs in this depositionally complex play have been abandoned, and large volumes of oil may remain unproduced unless advanced characterization techniques are applied to define untapped, incompletely drained, and new pool reservoirs as suitable targets for near-term recovery. Interwell-scale geological fades models of Frio fluvial-deltaic reservoirs will be combined with engineering assessments and geophysical evaluations in order to characterize Frio fluvial-deltaic reservoir architecture and flow unit boundaries and to determine the controls that these characteristics exert on the location and volume of unrecovered mobile and residual oil. These results will help identify specific opportunities to exploit these heterogeneous reservoirs for incremental recovery by recompletion and strategic infill drilling. Preliminary syntheses of reservoir log, core, and production data were undertaken to identify individual reservoirs with the greatest additional resource potential to target for detailed reservoir characterization studies. Representative logs for each field were selected to characterize overall depositional style and illustrate reservoir zones and associated production. Core analysismore » data from both fields were tabulated, summarized, and evaluated by reservoir to Identify and assess reservoir variability within the field. Production histories for individual reservoirs were reconstructed using available completion data. On the basis of these preliminary investigations and a general assessment of reserve growth potential of reservoirs within each field area, reservoir Intervals from Rincon and T-C-B fields have been targeted for detailed characterization studies.« less