Abstract: The shale of Carboniferous in central Tarim basin, the regional caprock overlying the oil/gas reservoir in buried hill of Lower Ordovician and Carboniferous, possesses three kinds of sealing mechanisms(physical sealing, pressure sealing and hydrocarbon concentration sealing) and plays an important role in oil/gas accumulation and preservation in the area of interest. Its comprehensive evaluation in this paper is based on the synthetic weight calculation from weighted averaging of different values which are set to different ranks of its seal capacity classified with major evaluation parameters following systematic analysis of its macroscopic and microscopic seal characteristics. Results showed that it has good-medium sealing capacity.

Key words: Tarim basin, Carboniferous, Shale, Caprock, Comprehensive evaluation