Recognition and depiction of special geologic bodies of Member 3 of Dongying Formation in Littoral Slope Zone, Qikou Sag

The purpose of this study is to forecast the profitable oil and gas reservoir, which is the key of finding hydrocarbon, based on the conception of special geologic bodies. With the guiding methodology of the research thinking of integration of point-line-surface by using the methods and techniques of logging, seismic, seismic attribute, and logging constrained inversion in 3D data volume, the special geologic bodies of Member 3 of Dongying Formation in Littoral Slope Zone of Qikou Sag, which has important hydrocarbon exploration potential, are recognized and described under the constraint of sequence stratigraphic framework. As a result, the developed scale, geometric shape and space distribution feature of the special geologic bodies are forecasted; the inner structure and sequence structure patterns of the geologic bodies are also ascertained. From the lowstand system tract (LST) and lacustrine expanding system tract (EST) to the highstand system tract (HST), the geologic bodies have evolved from relative centralization of lake basin reducing period to three relative dispersive isolated parts of broad lake basin period. According to the relevance and regularity of the development of geologic bodies, the conclusions can be obtained that three types of potential profitable reservoir traps, including the lithologic lens traps, lithologic updip pinchout traps and structural-lithologic composite traps, are forecasted. In addition, scientific basis for further hydrocarbon exploration in new area (few-well area and no-well area) is offered in the guidance of sequence stratigraphic model.