Seismic velocity tomography for CO2 monitor in subsurface geological structures
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Date
2018
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Publisher
Elsevier
Abstract
The storage of CO2 in depleted hydrocarbon reservoirs and saline water aquifers is a
leading solution to Global Warming due to CO2 emission to the atmosphere. The capture of
CO2 from major CO2-emitting plants and its storage in underground geological structures has a
potential to reduce Global Warming by about 60%. A procedure for monitoring safe and secure
storage of CO2 in underground geological structures is demonstrated in this study using seismic
velocity tomography. The tomographic method uses first arrival traveltime to estimate velocity
of geological structure along the ray path. The inversion procedure utilizes optimized objective
function that consists of two parts: (i) a part that minimizes the misfit between the observed and
inverted data, and (ii) a part that enforces the true shape and structure of the real geology. First,
the method is applied to invert the velocity structure of a west Texas oilfield, and later to reconstruct
the velocity structure of Marmousi models before and after CO2 injection. The results of the tests
confirm the appropriateness of the procedure for CO2 monitoring. The inverted velocity tomogram
for the post-injection stage shows velocity perturbation due to CO2 presence and the progression in
CO2 front. Technology for monitoring CO2 in geological storages as demonstrated in this study is
crucial to forestall CO2 leakages and its negative consequences on the environment.
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Keywords
Carbon capture and storage, Seismic velocity tomography, Ray theory, Global warming, Complex geological model
Citation
RAJI, W. O., HARRIS, J. M. and LU, S., (2018): Seismic velocity tomography for CO2 monitor in subsurface geological structures. Journal of King Saud University-Science. Vol 30(1). 57-64