A recently proposed paraxial ray-based technique for relative location of microseismicity is extended to accommodate several master events with respect to which other events, termed the slaves, are located. The multi-master extension addresses two issues inherent for the existing single-master algorithm: a gradual decrease of its accuracy with the distance from the master and less than satisfactory performance in the presence of strong velocity variations. Those deficiencies are handled by applying an improved paraxial traveltime formula, exact in homogeneous elliptically anisotropic media, and by distributing multiple masters in the subsurface to sample its heterogeneity. The contributions from different master events to the hypocenter of a given slave are automatically weighted to enhance the influence of adjacent masters, ensuring the precise slave location, and to suppress the influence of distant ones, tending to increase the slave-location errors. Tests of the multi-master relative event-location method on synthetic and field microseismic data demonstrate its precision and flexibility, as well as applicability to both surface and downhole microseismic geometries.

Presentation Date: Monday, October 17, 2016

Start Time: 3:45:00 PM

Location: 144/145

Presentation Type: ORAL

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