Lithology Identification and Reservoir Characterization of Epimetamorphic Rock Basement in Beir sag, Hailar basin, China

Lithology identification and its controlling on reservoir were the key problems to study on metamorphic rock basement reservoir. Taking epimetamorphic rock basement in Budate Group, Beir sag, Hailar basin, China for example, nine fundamental protolith rocks are identified and well log and seismic response standards for them are established based on core, petrographic thin section, well log crossplot and seismic facies study. The basement reservoir is dual-porosity type. Main reservoir spaces containing fractures and solution pores are caused by weathering and leaching, structural fracturing, and diagenesis to the different lithological rocks in basement According to the physical test and oil test data of different lithology, four grades of priority lithological sequences are classified, i.e., grade I with pyroclastic sedimentary rocks and normal medium-fine sedimentary rocks, grade II with pyroclastic rocks, grade III with sedimentary pyroclastic rocks and normal mudstone, level IV with intermediate-basic volcanic rock, corresponding to good, fair, medium and poor reservoir as well as oil yield. Finally, the seismic spectrum clustering and multi-attribute neural network clustering are applied to predict the distribution of priority lithological sequence as well as the development area of excellent reservoir. It will be helpful to guide reservoir research and hydrocarbon exploration of metamorphic rock basement.