The study about subsurface reservoir architecture and quality is important for the prediction of the remaining oil. Based on comprehensive analysis of core data, well logs, seismic and dynamic data, the different level of the... [ view full abstract ]
The study about subsurface reservoir architecture and quality is important for the prediction of the remaining oil. Based on comprehensive analysis of core data, well logs, seismic and dynamic data, the different level of the internal reservoir architecture were studied and the distribution of reservoir quality were clarified. The research showed that the distribution patterns of the braided stream is flake-like distributary while overbank sand body and the flooding plain scattered. Taking the layer of L3 (2) as an example, 7 single braided bands were further identified, which contained with wide braided bars and narrow channels. More than 80% of the single braided belt is occupied with the braided bar.
By comprehensive using grain-size, ordinary thin section, cast thin section, scanning electron microscope, mercury injection and other core analysing and testing data, the reservoir can be divided into four types. Class I reservoirs are high porosity and high permeability reservoirs where the pore is mainly composed of primary intergranular pore, the pore throat is pore-shrinking type, and the lithology is mainly composed of medium sandstone, which usually located in the braided bars; Class II reservoirs are middle and high porosity and medium permeability reservoirs, where the pore is dominated by intergranular pore and dissolution pore, the pore throat is contraction type, and the lithology is mainly fine sandstone and silty sandstone, which mainly distributed in braided channels; Class III reservoir is medium porosity and low permeability reservoir, where the pore is mainly intergranular pore, the pore throat is contraction type and sheet throat type,The lithology is mainly pelitic siltstone and pelitic fine-sandstone, which mainly distributed on the overbank; Clas IV reservoir is the worst, which mainly distributed on the overbank and the edge of the braided channels. The quality of braided river reservoir of L3 sand group is generally better, which mainly develops class I and class II reservoirs. The lateral continuity of type I reservoir is better, which also contained the lateral variation of reservoir type—Such as from class I to class II reservoir lateral changes. The quality of the reservoir is mainly controlled by the original deposition. It can be found that the different distribution of reservoir quality and the different configuration elements have better correspondence with the analysis of reservoir architecture.
Topics: Diagenesis , Topics: Fluvial depositional systems
