Using multiple downhole VSP arrays for monitoring passive microseisms
Zuolin Chen, Robert R. Stewart
Using a hypocenter location method, which depends on the P and S arrival times only, the hypocenter accuracy as determined by an observation network composed of one or more VSP arrays and several geophones in separate wells is calculated. Error analysis illustrates that the events recorded by this kind of seismic monitoring network can be located with an accuracy of 5m-10m within the network. Compared to the conventional VSP location methods which use hodograms and P and S arrival times, our method has the advantages of being convenient, reliable and much more accurate. Thus, we suggest using this kind of network to monitor passive microseismic activity and to locate the recorded events using P and/or S arrival times only in the future study. Besides, we also determined rules for the alignment of such networks.