The Research Of Reservoir Evaluation By Seismic Technology In The Metamorphic Bedrock In Liaohe Depression

The study project mainly focuses upon the technique problems about description andprediction of interior fracture within the base rock in seismic exploration of southern CentralRise in Liaohe Depression. The project takes advantage of different methods, such as structureinterpretation, seismic attribute analysis, hydrocarbon detecting and seismic pre-stackinversion, to characterize reservoir. The result may propose exploration suggestions andseismic technology applicability on metamorphic bedrock. This project has achieved thefollowed results.1. Established seismic frequency decay method to detect hydrocarbon.The project detected hydrocarbon by the decay of seismic frequency spectrum along withreservoir. This method considered continues absorbing to seismic energy in a horizon intervalwhich made for judging whole trend of frequency spectrum. Frequency spectrum decay in thetime-frequency map of seismic trace crossed well are consistent with oil test of the well.Frequency spectrum decay may be important evidence to exploration arrangement.2. Study seismic attributes apply to fractures prediction and indicated main fracturesdevelopment zone.The fractures development zone are mainly located two sides of Dawa Fault. Zones nearZhaogu3are also developed fractures. Coherence, Ant Cube and Volume Curvature aresensitive to fracture zone and faults. Principle Component Analysis may characterize fracturezone and inner faults.3. Established relationship between metamorphic bedrock lithology, fracture zonedevelopment degree with seismic response.Amphibolit and Lamprophyr in Archaeozoic may have apparent seismic reflection while theyconnect with other lithology. The reflectivity of any lithology may have seismic reflectionwhen it is more than0.012. The amplitude continuity are easily affected by seismic noise.Seismic reflections of fracture zones with high angle relate to dominate frequency of seismic,width and height of the fracture zones. The reflection would be more apparent when seismicdomination frequency is high or the fracture zones are width and long.4. Indicated the limitation of AVO attributes and pre-stack seismic inversion on metamorphic.The method of AVO attributes for hydrocarbon detecting has limitation for metamorphicbedrock in this area. Pre-stack seismic P-wave inversion has some effect on identify metamorphic lithology.5. Proposed key areas of exploration according to comprehensive analysis.The banding zones located two side of Dawa Fault have fully hydrocarbon source anddeveloped reservoir. A few of wells in this area have industrial oil production. The buried hills,fault blocks and fault step traps may be main exploration zones.