Study On The Post - Drilling Reservoir In The Section Of Weizhou 6-8 Oil Field

WZ6-8offshore Oilfield, which has been developed to be located on Beibu Gulf Basin, north of South China Sea, has drilled WZ6-8-1, WZ6-8-2, WZ6-8-3three exploratory wells and WZ6-8-A3H, WZ6-8-A3H1two horizontal wells in Liu I FormationlVinterval. The two horizontal wells were encountered several isolation lithological sand groups with poor sand connectivity, uncontinuous oil layer and small scale. This situation was totally different the recognitions before drilling with continuously distribution of sand groups and reservoir. Therefore, it should be rebuilding-in and reevaluation of the plane distribution characteristics of reservoir, lateral connectivity and potential reservoir distribution. There are three difficulties on reservoir research work after drilling currently:1. heterogeneous reservoir with poor continuity;2. the reservoir boundary defined unclear with shallow discrepancy of wave impedance;3. thin reservoir thickness, sand pinch and mudstone interlayer affected by obviously the resolution of the seismic waves.This paper is presented the study of the palaeostructure, sediment thickness, seismic analysis features combined with sandstone composition and heavy minerals etc. data, and the fine reservoir contrast, evaluation of reservoir heterogeneity, reservoir sand prediction and microfacies sedimentary analysis techniques was applied in analysis comprehensively to conclusion:the provenance of sandstone in Liu I FormationⅣinterval of WZ6-8Oilfield, came mainly from the two NE-bearing meandering rivers, and this newly discovered NS-bearing meandering river channel was laid on the deepest part of the river bed of enrichment sandstone reservoir, above the T81mudstone, shale and oil shale source rock. The top of water channel was covered with bay mud to form an independent lithologic traps, which may generate pool to be worthy of further exploration.