A Receiver Array Evaluation Method Designed For Surface Based Microseismic Monitoring

Surface based microseismic monitoring during hydraulic fracture stimulations is an emerging technology in the last decade. The method observes acoustic emission (AE) or microseismic events using a surface receiver array and estimates source locations and origin times of the events by analyzing a time series of migration images from observation data. However, the accuracy and monitoring cost of the technology highly depends on the array-geometry. The migration images can be blurred if a too coarse array is used. Monitoring cost can be unnecessarily high if a too dense array is used. Some sort of adequate array evaluation methods are required for designing a cost effective survey plan. We introduce an array evaluation method based on the point-spread function (PSF). The PSF describes the response of an imaging system to a point source. Our proposed method evaluates an array in the following way: First, a point source of which excitation time and source location are known is defined. Second, synthetic seismograms using the array are computed. Third, the synthetic traces are migrated and a time series of source images are obtained. Finally, the images are examined so that the abilities of the array are understood. We demonstrate the method by diplaying attributes calculated from the dataset which represent the precision and accuracy of the source location determination.