To
    explain how the major faults affect the gas reservoirs in the Xujiaweizi fault
    depression is of great significance to the exploration of complex volcanic gas reservoirs.
    In view of this, based on the 3Dseismic data of fine interpretation of the
    Xujiaweizi fault depression, the biplot of the distribution of basement faults,
    volcanic rocks and gas reservoirs is drawn and the volcanic structures are
    explained in detail. The conclusions are drawn as follows: 1) the volcanic gas
    reservoirs in the Xujiaweizi fault depression are mainly controlled by the deep
    fault system and basement faults play important roles in the development of
    volcanic rocks, reservoir stimulation, and charging with high-intensity gas
    source: 2) on the plane, the volcanoes are in the beaded distribution along the
    bedrock fracture trending and the bifurcation or turning points are the
    important panels of volcanoes; while from the vertical profile, multi-stage
    volcanic structures are overlapped; 3) at the later period of volcanic activity,
    the deep acid fluids upsurged along the fracture and extended along the
    unconformity surface to form quality reservoirs with favorable secondary pores;
    and 4) from the locations of well-developed volcanic facies, the eroded facies,
    the upper overflow subfacies, and spatiall fading subfacies all close to the
    fracture are favorable places for the forming of volcanic gas reservoirs.