CCS Monitoring with Time-Lapse VSP in China Northwest

Shenhua CCS (Carbon Capture and Storage) project is China's first complete carbon dioxide storage demonstration project, which has the whole process of coal-based carbon dioxide capture and the stratified CO2 detection in low porosity and low permeability deep saline layers. Multiple layers had been injected with CO2 between June 2011 and August 2013. In this paper, we used Shenhua CCS project, as an example, to describe the time-lapse VSP technology and to obtain CO2 injection monitoring results. Since two VSP observations have been conducted before and after CO2 injection, we obtained high-quality time-lapse VSP images. Through the calibration in depth domain and the integrated interpretation with variety of attributes, we analysed the responding characteristics of both VSP observations before and after CO2 injection. Then we predicted the potential spreading range of CO2 in the subsurface. This CCS project has achieved the desired objectives as expected.