Micro-seismic event location based on Newton iteration method and grid-search method

Inordertomaketheoptimizationalgorithmconvergentgloballyandquicklywhenlocatingmicro-seismicevents,consideringthegoodperformanceofgrid-searchingmethodonglobalconvergence andadvantagesofNewtoniterationmethodforcalculationspeedandaccuracy,alocationmethodbased ongrid-searchingmethodandNewtoniterationmethodisproposed.Firstanapproximatelocationresult isobtainedbygrid-seachingmethodwithsparsediscretizedgridsinthemonitoringareaandtheresultis theinitialiterationvalueforNewtoniterationmethod;secondNewtonmethodisappliedfortheaccurate locationresult.The influences of anisotropy of the velocity model and velocity measure error are analyzedinsimulationexperimentsandtheproposedmethodiscomparedwithNewtoniterationmethod, grid-searchingmethodandsimulatedannealingmethodaboutlocationaccuracy,efficiencyandstability.Thelocationresultsshowthattheproposedmethodcanlocatemicroseismiceventsaccurately,efficientlyandstably.Theproposedmethodisalsotestedwithfielddata. Thelocationresultislessthan4 m. Sothemethodispracticalformicroseismiceventlocations.