Study on Favorable Sedimentary Microfacies and Favorable Oil-bearing Areas by Energy Thickness of Single Permeability Sand Bed

Key words: 
• extra low permeability reservoir /
• single permeability sand bed /
• energy thickness /
• logging response /
• framework sandbody /
• favorable sedimentary microfacies belt /
• favorable oilbearing areas

Abstract: Aiming at identifying microfacies belt of Main Framework Sandbody and filtering the relative high permeability, high production favorable oilbearing areas with extralow permeability reservoir in the middle of Shanbei Slope of Ordos Basin, it was presented that using Energy Thickness of Single Permeability Sand Bed controlled and classified optimum sedimentary microfacies belt. Information of depositional energy and its thickness in Single Permeability Sand Bed is extracted by multi logging response , in other words, maximum depositional energy and its thickness variation of Single Permeability Sand Bed with the relative high permeability could be reflected by the latitude, thickness, figure, contact relationship and secondary form of logging curve and data size, by which it is confirmed that development, the scale and distribution of the Framework Sandbody of the underwater distributary channel microfacies and channel overlying debouch bar microfacies of delta front subfacies, meanwhile, the mistakes are effectively overcome which resulted in failing to successful identifying accumulate thickness and microfacies belt of Main Framework Sandbody of thin sand and sandstone and mudstone interbedding of several similar origin in the studied reservoirs. Throuth the statistics of naturalpotential, natural gamma, density, neutron, interval transit time, resistivity log curve, and lithology, physical property and Energy Thickness in the studied layers, the cutoffs criterion of Energy Thickness of Single Permeability Sand Bed and the elimination criterion of interlayer were proposed, and the information of Single Permeability Sand Bed and its Energy Thickness was extracted in extralow permeability reservoirs Chang 4+511 in the studied areas, by which classification of favorable sedimentary microfacies belt and distribution of its framework sandbody could be controlled, and the relative high permeability, high production favorable oilbearing areas which are different types were predicated and filtered, which sketching the extend tendency, form, and feature between the river channel body areas and Hua Chi oil field in the southwest. The results can offer favorable target , important positions and well field for enlarging reservoirs and raising yield in the extralow permeability reservoirs.