Shallow Gas Distribution Character of Heidimiao Reservoir in Southern Daqing-Changyuan Based on High-resolution Sequence Stratigraphy

By applying the data of drilling core, well logging and 3D seismics and studying the sequence framework, sedimentary microfacies and shallow gas distribution law, it shows that the Heidimiao Reservoir is vertically divided into a long-term, 4 intermediate-term and 25 short-term base-level cycles. Heidimiao Reservoir is of the gentle river controlled sedimentary system of delta front The main microfacies are underwater distributary channels, mouth bars and distal bars. Shallow gas is vertically distributed in the reservoir sandbody at the period of intermidiate hemicycles of late decrease or early rise in long-term hemicycles of the early fall. It is reasonable match of distribution discipline of single sandbody, gas source faults and structure that is the dominated factor for shallow gas plane accumulation. Based on the study above, 90 gas traps are depicted by applying the gas-water interpretation templates.