Seismic Data Inversion for Characterization of CO2 Storage Prospect of Ulleung Basin

Abstract

CO₂ geological storage plays a very important role in a government's objective of greenhouse gas emissions reduction. The biggest goal of CCS (Carbon Capture and Storage) is the storage of CO₂ in underground geological formations safely and permanently. Seismic data analysis is one of the core technology for the CCS site selection, characterization and MMV (Measurement, Monitoring and Verification) during post-injection. To understand the characteristics of the CO₂ geological storage in southern part of Ulleung Basin, we carried out the impedance inversion for the seismic data that KNOC acquired in 2012, and constructed porosity models and attributes of the prospects to review the possibility of CO₂ storage. Water depths in the area range from 100 to 150 m, and the target zone of interest is around 1.5 sec. TWT. For removing strong multiples observed in the data, amplitude preserved processing methods, SWD (Shallow Water Demultiple), SRME (Surface Related Multiple Elimination) and Radon Demultiple, were applied. From the seismic to well ties, log correlations were achieved on Gorae IX-1 (0.648), Gorae XI-1 (0.574) and Gorae VII-1x (0.342). All the three well logs were used in building the low-frequency model to generate more roust initial model. Simultaneous pre-stack inversion was performed on all of the 2D profiles and inverted P-impedance, S-impedance and Vp/Vs ratio from the inversion process were applied to predict rock property attributes such as volume of shale and total porosity. With the porosity profiles, the porous and non-porous zones can be identified for the purpose of the CO₂ sequestration initiative. There is still remaining uncertainty for the inversion results away from the well control, more detailed characterization and the CO₂ migration simulation with additional wells are essential for the domestic CCS demonstration.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015