Identification of Complex Ancient Volcanic in Carboniferous, Northern Xinjiang

Based on recent exploration of Carboniferous volcanic of Kelameili gas field in Junggar Basin, northern Xinjiang, a series of technology have been formed to identify lithology and lithofacies of complex ancient volcanic. Carboniferous volcanic types in this gas field are complicated and diversified; the identical lithology is different in texture, structure and component, as well as relevant typical characteristics, making it hard to identify lithology and lithofacies. According to the observation from 16 wells in Ludong area with 92 tubes of cores, 235 typical pictures and 631 sections, the article denominated the volcanic lithology. The lithologic and electric relationship of volcanic were built by the data of cores, sections and calibration logging, which laid a foundation for building the volcanic lithologic-electric plate. Density-gamma crossplot, acoustic-gamma crossplot and resistivity-gamma crossplot in Ludong area are made, and several complex volcanic types are identified, such as rhyolites, basalts, basaltic volcanic breccias, andesites and andesitic firing breccias. Through logging-seism-combined identification technology of volcanic lithofacies, the seismic properties of different volcanic types are distinguished, finally the distribution of explosive facies, outflow facies and volcanic sendimentary facies are divided both on plane and profile.