Abstract: Water content ratio is about 80% in the major reservoirs in the OLT oilfield.For making scientific proposal for exploitation, there is a need for the integrated assessment of reservoirs.On the basis of lithological, geological, production and logging data, the assessment is made about the reservoir lithology and physical properties and oil-bearing with grey system fine technique.The assessment criteria of reservoir lithology, physical properties and oil-bearing properties are established according to the matchup of cores, geology and oil testing with logging data in corresponding wells.For the wells having no cores, the geological parameters of reser voirs are calculated and then use the the criteria and technique of grey system theory to synthetically inter pret the logging data.The results provide a firm foundation for oilfield development in future.Also, The assessment parameters and criteria can be used in other similar oilfields.