Abstract
The identification of volcanic lithofacies is the basis for establishing volcanic institutions and making high-quality reservoir predictions. As the formation of Carboniferous volcanic rocks in Shixi area of Junggar Basin is strongly related to the cyclonic period of volcanic eruption and the location of volcanic channel development, the lithological variety changes rapidly and the lithofacies are complex. Moreover, the volcanic rocks had undergone strong weathering modification at later stage, the identification of volcanic facies becomes more difficult. This paper uses core observation, thin section identification, logging data and seismic attributes to classify and identify the lithology and lithofacies, and to summarize the methods of lithology classification and lithofacies identification of volcanic rocks in the study area. The lithology is mainly andesite and dacite, followed by volcanic breccia and tuff. Basalt and rhyolite develop locally in a few localities. The lithofacies of Carboniferous Period in Shixi area mainly consists of intermediate-acid effusive facies, followed by explosive facies, with basic effusive facies being rare and thinly developed, according to the well data. The volcanic conduit facies is developed only in a few places. The lithofacies are mainly identified based on the characteristics of the logging curves and the combination of external morphology and internal structure of the seismic reflections. The research method of this paper provides a case for the study of Carboniferous volcanic rocks and the dissection of volcanic edifices in Shixi Area.
