Signal to Noise Analysis of Densely Sampled Microseismic Data

Abstract

Abstract

The signal to noise ratio improvement due to noise cancelation inherent in stacking individual measurements is bounded by the square root of the number of channels stacked. Due to the non-impulsive radiation pattern of microseismic arrivals and local noise sources within an array, this upper limit is impossible to achieve. This study uses a densely sampled array designed for a 3D converted-wave reflection experiment to analyze the actual signal to noise ratio improvement as a function of channel count. After several hundred stations, the return on acquisition investment is minimal. Shear arrivals are more energetic than compression arrivals. The combination of both types of information makes a further improvement of available energy for each event. Shear arrivals often have low dominant frequency content. This example shows arrivals below the corner frequency of the hardware, which results in a lower signal to noise ratio than if broadband instruments were used. If sparse and/or irregular acquisition patterns do not evenly sample the radiation pattern, no benefits or even deleterious effects can be observed on the information content. Case studies and examples showing the decision impacts of such sufficient, if nearly optimal, acquisition stratagies will highlight how acquistion with broadband 3C instruments in a wide aperture grid.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016