Initiation of time lapse measurement to monitor the change of water table in water pumping at Al Wasee field, Saudi Arabia using a seismic ACROSS source and mulch-receivers (Preliminary report)

Abstract

We are developing a seismic technology for CCS, CO2-EOR and permanent reservoir monitoring using ultra-stable and long duration seismic source. We use seismic-ACROSS (Accurately controlled and Rousingly Operated Signal System) developed in Japan and multi-seismometers for the above purpose. We carried out synthetic evaluations of reservoir change imaging assuming single seismic sources and field experiment of time-lapse related to underground air injection in Japan in 2011, and. We are applying a seismic ACROSS in the context of carbonate rocks in Saudi Arabia. The Al Wasee water pumping site approximately 120 km east of Riyadh has been selected as a test-site. The intention is to observe the changes in aquifers induced by pumping operations although this is a very tough task because the aquifers seem to be distributed as diffused sources. One ACROSS unit was installed at the Al Wasee site this December 2011. The instrument has been operated from 10 to 50 Hz with 40 ton-f at 50Hz. We use a device with a horizontal rotational axis. Using alternatively clockwise and counterclockwise rotations we can synthesize vertical and horizontal forces, respectively. 31 three-components and 8 nearby geophones have been used to monitor the seismic changes from pumping the water. Comparing the data during one and half month, we identified waveform changes and clear daily variations. These waveform changes might be caused by the change of water table. In this report, we will show the preliminary results obtained in this field. This experiment is conducted in the cooperation by Japan and KACST funded by JCCP (Japan Cooperation Center, Petroleum) and KACST.