Seismic Response And Characterization Of Volcanic Rocks In The First Segments Of Yingchengzi Group,Longshen 303 Well Area,Songliao Basin

After more than thirty years of investment and development,Yingtai area of Songliao Basin has been entered into the stage of evaluating the potentials and risks of the first member of the Yingcheng.Though many researches were initiated in regards to the structure patterns,fracture systems,distribution of volcanic rocks and the characteristics of volcanic gas reservoirs of Longshen 303 well,and the recovery factor of oil fields is elevated to some extent,there is still a large amount of oils and gas left in the different parts of the underground.On the other hand,today's accuracy of seismic data interpretation can not meet the needs of increasing the recovery ratio of the oil fields in the later stage.Therefore,the research of seismic response and characterization of volcanic rocks is still the agendaThe lithology of Longshen 303 well in the study area is mainly rhyolite,followed by tuff,with a small amount of Anshan basalt and volcanic breccia.Based on that and the previous research results,the nineteen coring holes are classified according to the volcanic lithofacies,subfacies and the pattern of volcanic cycle.The volcanic facies types of overflow and outburst stage are divided into five subfacies(upper,middle,lower,airfall and thermal base surge subfacies),and three first-order cycles and five second-order cycles.After researching and studying the related files at home and abroad about the methods of volcano characterization in the volcanic gas reservoirs on the basis of effusion modes of volcanic rocks as well as combining with the local geology,logging and seismic data,the effusion mode of the local volcanic rocks are built in which the Longshen 303 district owns mainly two effusion modes: central eruption and fissure-central eruption.And the recognition standard is established based on the evolution laws of magmatic diagenesis,lithological change of single well,rules of longitudinal lithologic assemblage and characteristics of resistivity curve to recognize nineteen volcanic bodies.Through well-to-seismic integration as well as accurate seismic calibration,the recognition indication of seismic facies is established both on the surface and the inside of volcanic rocks.Based on the seismic reflection of the volcano surface,the horizontal distribution feature of the volcanoes in this district is determined with the assistant of plane attribute forecast.Under the framework of volcanic mechanism,the volcanic body characterization is initiated and finally the distribution pattern of volcanoes in this district is settled: twelve volcanic bodies with fissure-central eruption and seven volcanoes with central eruption.