Sandstone-mudstone interbed fault zones structure feature and controlling oil effect

Key words:  Sandstone-mudstone interbed  fault zones structure feature  controlling oil effect  Putaohua reservoir  Xingbei Oilfield  Songliao Basin

Abstract:

By using outcrop dissection, 3-D seismic interpretation, logging curve comparison, core observation and rock thin section identification, we studied the internal structure of the fault zones in sandstone-mudstone interbed strata of the Putaohua reservoir in northern Xingbei Oilfield, Songliao Basin. Based on the comprehensive responses of well logging, a model to predict fault zone thickness was established; with it we discussed how the fault structure controlled the distribution and enrichment of remaining oil along the fault edges. Our results reveal that the fault zones are mainly composed of a fault core and the damage zones; the fault core develops segmented structure of shale smear, while damage zones show features of crushing, sliding and deformation; the fault segments vertically into PI4 stratigraphic horizon, causing the three breakpoints in the coring well drills, where breakpoint 1 develops fault tip damage zones of sandstone deformation band, breakpoint 2 develops the major fault core of shale smear, and breakpoint 3 develops argillaceous breccia and minor fault core of mudstone fractures filled by calcite. With increasing distance to the fault core, the density of minor fractures and carbonate content are gradually reduced.