Time-lapse microgravity data acquisition in baseline stage of CO2 injection Gundih pilot project

Indonesia is conducting research on CO2 sequestration and monitoring in Gundih area. Geophysical methods are applied in the study area as monitoring technologies of CO2 storage in the subsurface. In this paper, we will describe data quality and baseline geophysical survey (2014 and 2016) as part of time-lapse microgravity (TLM) data acquisition. The same set of two relative gravimeters (Scintrex CG5) were used in 2014 and 2016 gravity data acquisition to provide TLM map. TLM can be useful to monitor the mass increase and decrease due to significant activities in the reservoir, but for this project TLM signal (caused by the CO2 injection in Gundih's reservoir) estimated very small. Considering current project status, no injection yet, the data acquisition in 2014 and 2016 will be analysed to help us understand non-target anomalies in near surface. Preliminary analysis of gravity differences between 2014 and 2016 shows correlation pattern of time-lapse microgravity with land use in the study area. Rice fields and villages in the Western part of the study area correlate with negative TLM anomalies and forest area in the Eastern part of the study area correlate with positive TLM anomalies.