Comparison of a vertical electric and a vertical magnetic source for cross well CSEM monitoring of CO ₂ injection

An adaptable technique for comparative image assessment: Application to crosswell electromagnetic survey design for fluid monitoring

“…Given the sensitivity differences that VMD and VED systems exhibit for resistive targets (Harris and Pethick, 2011;Grayver and Streich, 2014), an important question arising for CCS-specific survey design is whether the standard VMD system is adequate for delineating a resistive freshwater plume within the relatively conductive brine-saturated environment.…”

“…Complementing sparse borehole-based pressure measurements, due to its larger volumetric coverage, crosswell EM will aid the critical subtask of spatiotemporal plume mapping. The method has shown potential in a variety of applications that involve time-lapse monitoring of subsurface changes due to fluid flow (Alumbaugh and Morrison, 1995a;Wilt and Morea, 2004;Harris and Pethick, 2011;Hu et al, 2016) as well as for general reservoir reconnaissance (Hoversten et al, 2001(Hoversten et al, , 2004Shen et al, 2008;Wilt et al, 2008;Zhang et al, 2017). Here, we focus on the survey design based on simulations of the anticipated freshwater plume evolution.…”

“…The compactness of coils and the fact that casing effects can often be accounted for (e.g., Kirkendall et al 1999, Cuevas andPezzoli 2018), has given VMD systems greater attention both in the field as well as in theoretical studies (Spies, 1992;Alumbaugh and Morrison, 1995b;Liu et al, 1995;Spies and Habashy, 1995;Alumbaugh and Newman, 1997;Zhang et al, 1996;Zhang and Liu, 2000). However, it has been found that VMD systems face sensitivity limitations in the presence of typical CCS targets, that is, thin resistive anomalies within conductive regimes (Kong et al, 2009;Harris and Pethick, 2011;Grayver and Streich, 2014). On the contrary, vertical electric dipole (VED) systems are better suited for such targets (Grayver and Streich, 2014).…”

3D modelling for time-lapse cross-well CSEM monitoring of CO2 injection into brine filled reservoirs.

“…At present the only cross-well CSEM systems commercially and readily available are based on vertical magnetic dipole (VMD) transmitting and receiving antennas (SLB, 2008). While the VMD antennas are the only transmitters in use a good case could be made for development of a vertical electrical bipole cross well CSEM source (Harris and Pethick 2011).…”