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| | Abstract | | We have started gravity monitoring at a CO2 sequestration field in collaboration with Southwest Regional Partnership on Carbon Sequestration. One of the purposes of our study is development of monitoring methods which are cost-effective to apply and bring about additional and independent information to complement 4D seismic data. Microgravity monitoring is thought to be a promising technique for evaluating CO2 geological storage. Reservoirs, however, are relatively thin and deep, resulting in subtle time-lapse signals at the earth's surface that must be compete with the presence of noise. Recent advances in superconducting gravimeters (SG) are quite attractive. We can extract gravity changes with nGal accuracy by applying time series analysis to data from continuous SG measurements. As the first step of our monitoring, a couple of pillars were made at the test field for parallel measurements with an absolute gravimeter and a SG meter. The first absolute gravity measurements were made using an A10 absolute gravimeter at the site in December 2011. Variance of the data was smaller than usual so that the location was evaluated to be a good base station for microgravity monitoring. |
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