摘要：The Karashayi Formation is a thin interbedded sand and mudstone. The thickness of a single layer of sand is thin, and the lateral change is fast. The res-ervoir heterogeneity is strong, and it is difficult to be identified regardless of seismic or logging. How to effectively identify the reservoir seriously restricts the further development of this reservoir. Therefore, it is of great significance to do in-depth study of its reservoir characteristics and to clarify the main con-trolling factors affecting reservoir development. This article takes the Carboniferous Karashayi Formation in the Tahe Oilfield as the main research object and makes full use of existing drilling data and predeces-sors. This study, based on the study of stratigraphy and sedimentary facies, have carried out systematic research on the characteristics and diagenesis of the Carboniferous Karasay Formation reservoir through a large amount of work on key well core observa-tions, thin section descriptions, and sample labora-tory analysis. The results show that the lithology of the sand and mudstone section of the Carboniferous Karasayi Formation in the part of the Tahe River is dominated by coarse-fine-grained feldspar quartz sandstone, lithic quartz sandstone, feldspar lithic sandstone, and lithic feldspar sandstone, with low degree mature rock composition. The types of dia-genesis mainly include compaction, cementation and dissolution. The type of pores is dominated by inter-granular pores and intragranular pores. The average porosity of the reservoir in the study area is 9.8%. mainly between 6-15%, and the average permeabil-ity is 42.89×10-um²， mainly distributed between 1-10×10-um². The overall appearance of the pores is the structural characteristics of medium pores and small throats, small pores and fine throats, with poor pore throat connectivity.
