Reservoir Heterogeneity Under Sequence Frame And Reservoir Assessment In Xinganling Reservoir Of Sudeerte Oil Field

Considering the geological characteristics of fault complexity, variable stratigraphic thickness, bad continuity of reservoir, quick variability of physical property, strong heterogeneity and development circumstance of Xinganling Reservoir in Sudeerte oil-field, applying different exploration and development data, guided by the theory and technology of high resolution sequence stratigraphy, sedimentology, reservoir geology and development geology, high resolution sequence stratigraphic correlation, sediment micro-facies, physical properties, heterogeneity under sequence frame, distribution of oil and reservoir assessment had been studied. All this provided references for adjusting development in the oil-field. The main results of this dissertation are listed as follows:(1) Referred to the research of the previous stratigraphic correlation, Xinganling Reservoir can be divided into 3 long-term cycle and 13 middle-term cycle. In order to finely study reservoir, 26 subzone may be divided under confined middle-term cycle in main oil-bearing series.(2) Near source, fast, underwater, strong hydropower and weak oxidation to weak deoxidation environment can be judged from core observation, sedimentary background and characteristics during the depositional stage of Xinganling Reservoir. Reservoir sand bodies are mainly underwater branch river channel, natural dike, crevasse splay, sand sheet and distal bar. The distributions of sand bodies are controlled by the location in the sequence stratigraphy and sedimentary micro-facies, so the thickness of sand bodies is high near the transform of middle-term cycle. The sand bodies of Bei16 and bei14 block are more stable, thicker and more connective than Bei28’s. Porosity and permeability models were built and the reservoir is middle-low porosity, too low permeability based on the interpretation result. Porosity and permeability are becoming small with increasing depth, but during the depth of 1600-1800m there is a secondary porosity zone. Porosity and permeability are good in the secondary porosity zone.(3) Heterogeneity of reservoir could be analyzed under sequence frame. Muddy interbeds are not stable in Sudeerte oil-field and heterogeneity in the sand body is middle or strong. For example, permeability variation coefficient in the sand body is mainly at 2.The sand bodies often moved, complicatedly superimposed and badly connected. Barrier beds is not stable and in some area there is not muddy interbeds. Heterogeneity between sand bodies is strong and permeability variation coefficient are all over 2. Base level cycles under sequence frame control the reservoir heterogeneity. Short-term cycle controls reservoir heterogeneity in sand bodies and there are 4 models, such as upward favorableness, upward disadvantage, upward favorableness again disadvantage and upward no large change model. Long and middle term cycles control intrabed and plan heterogeneity. Near transform surfaces sandbodies are in great distribution, high thickness and good physical properties, on the other hand, near flood surfaces sandbodies are isolated distribution, in low thickness and bad physical properties.(4) Pore forms are mainly original and secondary and sometimes micro-fissure. Throats mainly are pore reduction and necking type and the diameters of throats are small. The clay content is over 10% in reservoir, so the velocity sensibility is strong.(5)The structure controls the distribution of reservoirs, reservoirs are located in fault blocks in upthrows of big faults, oil in the upper part and water in the lower part generally. Applied assessment method of multi-parameter, Xinganling reservoirs were classified 3 types by subzones and the first type of subzones are mostly located near the base levels of middle-term cycles.This study suggested a way of research and technological methods by fine stratigraphic correlation, heterogeneity and reservoir assessment on complicated fault block reservoir. This technology is very effective to improve the development and recovery for Xinganling reservoir and also very helpful for the similar reservoir development.