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Bohai Bay basin, a typical extensional rift basin, and Ordos basin, an intra-craton down-warped basin, represent two important basin types in China. Because of their respective features, the main control factors for their high quality reservoirs are different. In Bohai Bay basin, the sandbody shows great variety in types and severely separated distribution and its high quality reservoirs are mostly controlled by the vertical secondary pore and vertical abnormal pressure. On the other hand, the sandbody in Ordos basin features a relative lack of variety, good continuity, indistinct vertical zone, and its reservoirs are mainly controlled by the diagenetic differentiation caused by different sedimentation inside the sandbody. Therefore, in the Bohai Bay basin, the exploration should be based on the analysis of sedimentary facies and the favorable diagenetic zones and formations. The focus in Ordos basin, however, should be put on the relatively high permeability sandstones in a generally low permeable sandstone background. |
