Hydrocarbon accumulation conditions and reservoir distibution sequence of Dongying formation in Jiyang depression

Abstract：As an important depositional stratum at late fault depression deposition, Dongying formation has become an important increasing reserve during “the 13 th five-year plan”period in Jiyang depression.However, the degree of exploration is obviously lower than that of the other upper and lower stratum.The main problems restricting the exploration of Dongying formation are unclear trap pattern and its formation mechanism, unclear regularity of reservoir-forming.Based on the analysis of sedimentary tectonic setting of the large braided river delta in the Dongying formation, the reservoir-forming conditions of Dongying formation of different structural lithofacies belts were analyzed through the statistical analysis of the static elements of Dongying formation reservoirs and the dissection of typical reservoirs, and the reservoir distribution sequence of Dongying formation in the Jiyang depression was established, which were the series of stratigraphic-unconformity oil-gas reserviors developed in the uplift belt at the basin margin, a series of structural reservoirs controlled by oil source faults, mudstone caprocks and complex traps in the central shallow-slope zone, and a series of lithologic reservoirs controlled by source rocks and overpressure systems in the deep depression zone in the north of Jiyang depression.The distribution sequence of the reservoir in Dongying formation broke through the separation of the distribution, forming a kind of distribution sequence across the depressions.The unstanding of the reservoir distribution sequence had important practical significance for guiding the exploration of different types of reservoirs in Dongying formation.

Keyword：Dongying formation;accumulation condition;reservoir distribution sequence;Jiyang depression;