Abstract: According to hydrocarbon generation history of gas source rock, reservoir thermal history and reservoir bitumen of Minfeng area in Dongying sag, comprehended gas accumulation geological background, the genetic types and characteristics of middle-deep gaspools are analyzed, and the gas accumulation model is set up. The middle-deep gas having been discovered is mainly cracked gas and comes from the lower Es₄ source rock. There are three genetic types and gas accumulation models: kerogen-cracking gas directly entered traps and formed gas pool, kerogen-cracking gas infilledpaleo-reservoir and formed gas invasion enrichment gas pool, paleo-reservoir oil cracked and formed gas pool. Be controlled by the evolution of the source rock, the distributional characterization of three types of the gas reservoir is obtained. The central of the sag is mainly accumulated with pure gas reservoir composed by cracked gas from kerogen, and some cracked gas generated from ancient oil reservoir. Slope zone is accumulated with gas invasion enrichment gas pool. There is only oil pools charged at late stage on the relatively shallow slope edge. From the central area of sag to the high slope area, the distribution model that gas, oil gas mixed phase and oil coming in turn forms.

Key words: Dongying sag, deep zone gas, genetic types of gas, reservoir bitumen, accumulation model, reservoirs