LITHOLOGICAL SCRUTINY OF A SANDY CONGLOMERATE RESERVOIR:TAKING CFD OILFIELD IN BOHAI AS AN EXAMPLE

The sandy conglomerate usually has large thickness, coarse grain size, less mud, dramatic change in lithofacies and strong heterogeneity. Such properties will bring difficulties to reservoir evaluation, especially in offshore area when oil exploration wells are few. This paper takes the CFD oilfield in the Bohai Bay as an example. Data of core, thin section, grain size, and logging are integrated. Combined the logging with lithology, a set of lithology discrimination model is made for reservoir identification. By description of microscopic features of pore types, pore structures and properties, we analyzed the relationship of sedimentary microfacies, lithology and properties. It is considered that lithology is the major controlling factor of reservoir property, upon which the most favorable reservoir is identified. Finally, the prediction of the spatial distribution pattern of reservoir is made with seismic attributes extracted. The results have founded a detailed geological basis for oilfield development program and provided technical references for describing the thick reservoir formed under similar geological conditions.