Abstract: In view of the volcanic reservoir-forming particularity, this paper analyzes the controlling factors of the volcanic reservoir of Kalagang formation of the Upper Carboniferous in Niudong oil field in oil source condition, premium reservoir genesis, structural setting, etc. The result shows that the lithology of this reservoir is dominated by andesite and basalt, secondly by volcanic breccia; solution cavity and fracture are its main types of reservoir space; oil and gas originated from such hydrocarbon source rocks as underlying Harjiawu formation (C₂h) dark mudstone and carbon mudstone migrate upward to the top of volcanic rock along the fault, then laterally to the local structural highs along the permeable layers below the unconformity surface, and accumulate as the strati-lithologic reservoir. It is concluded that favorable reservoir rock condition, fracture channel, paleo-structural setting and enough oil source are important factors to control the reservoir formation in this area.

Key words: Santanghu basin, Malang sag, Carboniferous, volcanic rock, reservoir rock, hydrocarbon accumulation