Monitoring and surveillance (M&S) is one of the key requisites for assessing the effectiveness and success of any onshore and offshore CCS/CCUS project. It will help understand, track, monitor, and predict the injectant plume migration, flow paths, and breakthrough times. The M&S helps in quantifying sequestered injected gas and any inadvertent leakage. It provides a good understanding of the remaining oil saturation (ROS) and its distribution in the reservoir.
In this manuscript, a comprehensive monitoring and surveillance (M&S) program is developed and discussed for the onshore and offshore CCUS/CCS projects. A range of monitoring techniques are available for the CO2 geological storage in onshore and offshore reservoirs. The advanced M&S plan incorporates conventional, advanced, and emerging novel technologies for wellbore and inter-well measurements. Both deep focused (providing surveillance of the reservoir and deeper overburden) and shallow-focused (providing surveillance of the near seabed, seabed and water column). These include advanced time-lapse pulsed neutron, resistivity, diffusion logs, and bore-hole gravity measurements, cross-well geophysical measurements, water and gas tracers, geochemical, compositional and soil gas analyses, and 4D seismic and surface gravity measurements.
Results from monitoring and surveillance technologies provide a better understanding of the reservoir dynamics within the subject area. The results can be used to refine the reservoir simulation model and fine tune its parameters. This paper reviews some proven best practices and draws examples from ongoing projects and related novel technologies being deployed for onshore and offshore reservoirs. It will then look at the new horizon for M&S technologies for onshore and offshore CCS and CCUS projects.