Chengdao Oilfield Museum On The Fine Reservoir Description

The Chengdao oilfield is an offshore field in Shengli oil province. The upper Guantao formation is one of the oil-bearing and oil-producing series with 72 percent of gross reserves in place of this oilfield. By the end of 2001, its estimated productivity has been amounted to 287×106 t. In this paper, based on regional sedimentary settings, sedimentary theories, seismic reservoir prediction and reservoirs description technologies, fine reservoirs description is done to upper Guantao after overall and systematic researches into stratigraphic models, structural models, sedimentary microfacies, reservoirs' heterogeneity, fluid properties, reservoirs' temperature/pressure system, oil-water relationship and reservoir types. And sedimentary microfacies of the main reservoir sands has been divided according to regional background, lithology or rock texture, sedimentary structure, sedimentary rhythm, grain size analysis, palaeontological assemblage, log and seismic facies. With all the heterogeneity appraisal parameters, the macro-heterogeneity of reservoirs has been evaluated quantitatively. Reflective characters of various sandbodies and their assembly have been interpreted finely both in normal seismic profile and inversion profile, using seismic forward technologies. This increases the accuracy for interpretation greatly. Due to 5/6 wells are slant holes in developing cluster wellgroup, environmental corrections are made to acoustic logging data of deflecting wells. Through synthesis seismic records, quasi-velocity is calculated and seismic calibration of deflecting data is carried out. Thus many data of deflecting wells can be used for seismic inversion and the problem of multiple solutions can be solved to some degree. This technology comes up to advanced domestic standards. Because the water base used to make up drilling mud comes from seawater, researches are made into the effects on resistivity of saltwater mud invasion and the values-selecting methods in reserves calculation are broken through, which continues to use terrestrial oilfields' parameters. Then interpretation models are established for saturation, porosity and permeability of unconsolidated sandstones in offshore area. By making full use of drilled wells data in development area, real reserves in place are calculated with volumetric method and non-producing reserves are evaluated to upper Guantao formation, providing reserve position for programming of this offshore oilfield in 2000 and in 2001. Using 3-D EV modeling technologies, 3-D geological models are established in the development area of Chengdao oilfield. These are successful e xperiences in fine reservoirs description for similar oilfields and have made good economic profits and social profits.