Abstract: The reservoir characteristics,controlling factors and sensitivities of the Middle Jurassic Toutunhe Formation in Fudong slope,Junggar Basin,were studied based on core observation,casting thin section identification,assisted with some analytical and experimental data on cores,such as SEM data,physical property depiction,x-ray diffraction results,pore structure and sensitivity test.Results show that:(1) the most favorable micro-facies for reservoir development is underwater distributary channel at delta front and its lithology is mainly composed of feldspathic litharenite that is low in compositional maturity and medium high in textural maturity.The reservoir space is mainly primary residual intergranular pores,partly intergranular and intragranular dissolved pores;(2) displacement pressure and mean saturation pressure are relatively low,but the pore throats are well-sorted,narrow as a whole,and are dominated by capillary throats;(3) reservoir development is controlled by both sedimentary microfacies and diagenesis;the early diagenetic chlorite rim cementation is beneficial to the preservation of some primary pores and throats,but compaction and pressure-solution causes the shrinkage of the primary pore space,the lowering of reservoir permeability,and the tightening of reservoir rocks.In addition,the sandstone reservoirs of the Toutunhe Formation generally have various sensitivities,which is one of the main causes of reservoir damage.Among them,the medium strong water sensitivity is the strongest in reservoir damage,followed by the medium weak acid sensitivity and salt sensitivity,while weak velocity sensitivity is hardly harmful.

Key words: sedimentary microfacies, diagenesis, sensitivity, reservoir characteristics, Toutunhe Formation, Fudong slope, Junggar Basin