Abstract: Hydrocarbon reservoirs in Bohai are mainly complex faulted-blocks.During the process of reserves evaluation,great problems have been occurred,such as unit classification,interface selection and effective thickness determination.Through seismic interpretation technology and reservoir description technology,the spacial distribution of main sand bodies has been made clear,which lays good foundation for effective thickness determination and oil-bearing area selection.At the same time,in combination with new logging interpretation technology and cable formation testing pressure data,the lower limit of effective thickness,reservoir types,fluid interface and reservoir connectivity have been confirmed. Through specific research,a set of scientific reserves evaluation methods have been summed up,which can provide great guidance for reserves research of similar oilfields.