microseismic general Flashcards
For both surface arrays and shallow shallow
buried grids, the ____ accuracy is very low.
Compared to a surface array, the receiver density reduces significantly in the shallow buried grids in which _________(3C) receivers are deployed in 20–180 m deep boreholes
Before starting a pre-survey design study, it is important to know the availability and accuracy of these modeling tools. Also, understanding the limitations of these tools is important which requires asking key questions including:
An ____ model, which is typically
built from the sonic and density logs, is calibrated using both the available P and S-wave arrival times and the back-azimuth estimates from the P-wave signals on the available perforation shots or string shots.
The hypocenter location for each event is then estimated by
using the available arrival times and polarization angles (back-azimuths). In the case of multi-well monitoring data, hypocenter locations can be estimated reliably using the _____ arrival times only.
Fracking related microseismic events often have negative _____ magnitudes
Typically, we apply a _____ filter to the microseismic data to remove any unwanted noise and focus only on the frequencies of interest.
For downholemicroseismic data, we begin with the instrument response correction and the conversion of amplitude units to ground displacement or ground velocity. The 3C waveform data is then _____ corrected to remove any DC bias
Fracking related microseismic events often have _____ moment magnitudes
The ______ (Q) in the medium affects the traveltime, frequencies and the amplitudes of recorded waveforms. Prior knowledge of Q values from seismic data is, therefore, important for assessing the event detectability.
The loss of energy is _____ proportional to Q for each wavelength of travel through the medium.
how is the youngs modulus and poissons ratio related to the total seismic moment released during hydraulic fracturing (Mtotal)
The processing of surface and shallow buried grid is often done on the vertical component recordings that contains the ___-wave information However, Artman et al. (2012) argued that the survey design and processing scheme should adequately handle ____-waves, which dominate the energy radiated from the source. By using both ___ and ___-waves, we can improve the depth accuracy of microseismic events from the surface and near-surface microseismic data
A receiver array that is _______ to the treatment zone records
events with overlapping P and S-wave arrivals, which are difficult to process, and cause additional complexities to accurate estimation of their hypocenter locations
Depending on the orientation of the symmetry axis, a TI medium
can be called _________ (TTI; dipping
layers or set of fractures).
surface and near-surface arrays have lower _____
sensitivity mainly because of the large source-receiver distance
Using the ___-wave arrivals on the calibration
shot (e.g. perforation shot, string shot or a ball drop event), we compute the receiver orientations.
The _____ from the analogue settings can be used to estimate the number of detectable events (NEV ) above a given magnitude threshold (MC), often called the magnitude of completeness.
Typically, we use _____ to represent this energy loss with respect to time or distance.
network. We can also determine the ____ orientation and ______ mechanism.