Abstract:

The paleogeomorphology of Block 14 and 17 which is high in the east and low in the west in the region is further characterized and an NS trend paleobarrier island is identified in H oilfield according to sand thickness, structural inversion, core and kaolinite content in drilled wells. The sedimentary microfacies of M1 are described under the guidance of sedimentary model. The results show that H oilfield is mud flat and mixed flat, N oilfield is sand flat and tidal channel, KS oilfield is located in subtidal zone while W oilfield deposits tidaldominated delta sediments. The analysis of reservoir and oilbearing characteristics controlled by microfacies indicates that tidal channel and sand flat sandstones are favorable reservoirs with midhigh porosity and extrahigh permeability, mainly distributing in the slope. Meanwhile, reservoirs in mixed flat and mud flat with thin sandstone and limited distribution are poor oil layers or dry layers on the top of the structure. Therefore, structurallithological oil reservoirs are formed due to the special matching relationship between both structure and reservoir.

Key words: Oriente Basin, Napo Formation, paleogeomorphology, tidal flat sedimentation, reservoir prediction