Study Of 4D Multicomponent Data Forword Model In CO₂ Geological Storage

CCS is recognized as the most effective way to mitigate the greenhouse gas effect. Geological storage of carbon dioxide is one of the key technologs of CCS.4D seismic monitoring technique is the most effective way to confirm the safety of CO₂ sequestration. Conventional 4D seismic technology emphasizes on analyzing reflection information from P-P wave. My study embarked on converted wave, and I had built 4D multi-component forword model.Based on 4D converted seisimic data acquired in Weyburn oil filed Canada, and theory of isotropic and anisotropic media, I make two-layer models and well models. Then I studied the change of converted wave reflection coefficient and converted wave synthetic seismogram via pore pressure and CO₂ saturation effects. At last, after calbriting stacked converted wave sections, and making stacked converted wave section to match stacked P-P wave section, I explored the research methods for 4D converted wave forword model in CO₂ sequestration.My study shows that:1) No matter from two layer model and well models of porous and vertically fractured HTI media, converted-wave reflection coefficient is more impacted by pore pressure than CO₂ saturation.2) In vertically fractured HTI media two layer model, the PS1 and PS2 AVAZ curves show same variation tendency, where PS1 reflection coefficient is more influenced by pore pressure than PS2 reflection coefficient; With the increasing of pore pressure, PS1 wave reflection coefficient will be increased.3) In vertically fractured HTI media two laye model, PS1 wave and PS2 wave have their own characteristics azimuth angle. 4)In fracture media model which assumed change of fracture, there is a positive correlation between fracture density and pore pressure, and fracture density has no related to CO₂ saturation, reservoir petro physical parameters is subject to the double effects of pore pressure and CO₂ saturation, and the change of pore pressure is dominating factor. PS2 wave is more sensitive to the change of fracture porosity.5) Pore pressure has strong influence on converted wave synthetic seismogram, CO₂ saturation has little influence on converted wave synthetic seismogram, and pore pressure is the key factor for difference of 4D converted seismic data.6) In same CO₂ saturation, the greater pore pressure difference, the greater difference in converted wave synthetic seismogram. In same pore pressure difference, the higher pressure, the greater difference in converted wave synthetic seismogram. With the increase of pore pressure, converted-wave synthetic seismogram is more sensitive to pore pressure.7) At present, Interpretion of 4D multi-component seismic data is greatly restricted by processing technology of 4D converted wave.