Lithology and lithofacies characteristics analysis and reservoir identification of Carboniferous volcanic rocks in Hongche fault zone

Key words:  Hongche fault zone  volcanic reservoir  lithology recognition  lithofacies characteristics  reservoir identification

Abstract:

The logging response characteristics of different lithologies are analyzed, the combined lithology identification charts are established, and the dominant lithology characteristics are defined, by combining logging cuttings, logging curves and thin section data. Based on the idea of core calibration logging and the characteristics of volcanic reservoir, the lithology and lithofacies of the Carboniferous reservoir in the study area are finely divided, and the characteristics of volcanic facies are identified. Combined with the conditions of reservoir and caprock and seismic reflection structure and configuration, the characteristics of volcanic institutions and the distribution law of oil-gas reservoirs are analyzed. The spatial distribution of the superior reservoirs is determined by using seismic multi-attribute analysis and slicing technology along the layers, and by comparing the seismic plan-section results with the favorable reservoirs on the well. The results show that the crossplot of density and resistivity/natural gamma can be used to better distinguish basalt, andesite and volcanic breccia. The crossplot of resistivity and natural gamma/density is better for distinguishing volcanic breccia, andesite and tuff. The tuff of volcanic eruption and volcanic sedimentary rock of discontinuous period form a good caprock. The andesite/basalt of overflow facies and the volcanic breccia of explosive facies form a good reservoir.The distribution range of favorable reservoirs can be better characterized by a comprehensive application of seismic texture, instantaneous phase cosine attribute and slicing along layers. Volcanic rock reservoirs in the study area are heterogeneous lithologic reservoirs jointly controlled by lithology and volcanic institutions.