Layout of CCS monitoring infrastructure with highest probability of detecting a footprint of a CO2 leak in a varying marine environment

Abstract

a b s t r a c tMonitoring of the marine environment for indications of a leak, or precursors of a leak, will be an intrinsic part of any subsea CO 2 storage projects. A real challenge will be quantification of the probability of a given monitoring program to detect a leak and to design the program accordingly. The task complicates by the number of pathways to the surface, difficulties to estimate probabilities of leaks and fluxes, and predicting the fluctuating footprint of a leak. The objective is to present a procedure for optimizing the layout of a fixed array of chemical sensors on the seafloor, using the probability of detecting a leak as metric. A synthetic map from the North Sea is used as a basis for probable leakage points, while the spatial footprint is based on results from a General Circulation Model. Compared to an equally spaced array the probability of detecting a leak can be nearly doubled by an optimal placement of the available sensors. It is not necessarily best to place the first in the location of the highest probable leakage point, one sensor can monitor several potential leakage points. The need for a thorough baseline in order to reduce the detection threshold is shown.

Developments since 2005 in understanding potential environmental impacts of CO2 leakage from geological storage

“…Primarily, models have quantified the spatial and temporal dynamics of a range of leakage scenarios (Chen et al, 2005;Blackford et al, 2008Blackford et al, , 2009Blackford et al, , 2013Dewar et al, 2013;Phelps et al, 2015), initially to understand impact potential but increasingly to address detectability and monitoring strategies (Hvidevold et al, 2015;Greenwood et al, in press). Models can also be used to aid leakage quantification (Mori et al, 2015), to underpin baseline understanding and in the future to directly assess impacts on ecosystems, as has been done for OA (Artioli et al, 2014).…”

Coastal monitoring strategy for geochemical detection of fugitive CO2 seeps from the seabed

“…The situation regarding natural variability will vary from one location to another, reinforcing the need expressed elsewhere for appropriate baseline survey (Blackford et al, 2014;Hvidevold et al, 2015).…”

“…The layout of monitoring infrastructure for detection of CO 2 leaks from sub-sea storage has recently been tackled by Hvidevold et al (2015). Like us, they use a numerical plume model to define the spatial footprint of dissolved CO 2 leaking from the seabed.…”

“…Like us, they use a numerical plume model to define the spatial footprint of dissolved CO 2 leaking from the seabed. The main difference with the approach taken here is that, unlike Hvidevold et al (2015), we have chosen not to provide any prior information on the location of leaks.…”

Cost efficient environmental survey paths for detecting continuous tracer discharges

“…Hvidevold et al . [] presented a procedure for optimizing placement of fixed sensors on the seafloor that accounts for footprint anisotropy. The same tracer footprint predictions, consisting of time series in an array of 51 × 51 grid points around the seep location from the GCM simulations presented in Ali et al .…”