Fine description and geologic modeling for volcanic gas reservoirs

To understand the geology of volcanic gas reservoir development, research was carried out on volcanic rock, body lithology, lithofacies, fractures, gas and water zones, reservoir classification, and geologic modeling for volcanic gas reservoirs. The volcanic rock body identification and anatomy reveals the spacial distribution and geometric parameters of volcanic rock body. The lithology and lithofacies research shows that, favorable lithology of volcanic rock includes volcanic breccia, vesicular basalt, vesicular ryolite and breccia lava, and favorable lithofacies includes air fall and spatter subfacies of explosive facies, and upper and lower subfacies of effusive facies. Based on FMI imaging, nuclear magnetic logging and traditional logging methods, fracture parameters were interpreted. By use of coherence, curvity and dip angle methods, comprehensive fracture prediction were performed, which reveals the distribution of fractures in volcanic rock. Nuclear magnetic, dublet transverse wave and traditional logging data were applied to identify gas and water zones, with the conformity ratio up to 90%. The prediction research on reservoir classification based on “volume control” indicates the spacial distribution of volcanic reservoirs. By means of volume control structure modeling and seismic control attribute modeling, models of structure, framework, matrix and fracture parameters for volcanic dual-media reservoir were built.