TY - JOUR

T1 - Approximate traveltime inversion in downhole microseismic monitoring

AU - Yaskevich, Sergey

AU - Duchkov, Anton A.

AU - Ivanov, Yuriy

PY - 2020/3/1

Y1 - 2020/3/1

N2 - In downhole microseismic monitoring, accurate event location relies on the accuracy of the velocity model. The model can be estimated along with event locations. Anisotropic models are important to get accurate event locations. Taking anisotropy into account makes it possible to use additional data – two S-wave arrivals generated due to shear-wave splitting. However, anisotropic ray tracing requires iterative procedures for computing group velocities, which may become unstable around caustics. As a result, anisotropic kinematic inversion may become time consuming. In this paper, we explore the idea of using simplified ray tracing to locate events and estimate medium parameters. In the simplified ray-tracing algorithm, the group velocity is assumed to be equal to phase velocity in both magnitude and direction. This assumption makes the ray-tracing algorithm five times faster compared to ray tracing based on exact equations. We present a set of tests showing that given perforation-shot data, one can use inversion based on simplified ray-tracing even for moderate-to-strong anisotropic models. When there are no perforation shots, event-location errors may become too large for moderately anisotropic media.

AB - In downhole microseismic monitoring, accurate event location relies on the accuracy of the velocity model. The model can be estimated along with event locations. Anisotropic models are important to get accurate event locations. Taking anisotropy into account makes it possible to use additional data – two S-wave arrivals generated due to shear-wave splitting. However, anisotropic ray tracing requires iterative procedures for computing group velocities, which may become unstable around caustics. As a result, anisotropic kinematic inversion may become time consuming. In this paper, we explore the idea of using simplified ray tracing to locate events and estimate medium parameters. In the simplified ray-tracing algorithm, the group velocity is assumed to be equal to phase velocity in both magnitude and direction. This assumption makes the ray-tracing algorithm five times faster compared to ray tracing based on exact equations. We present a set of tests showing that given perforation-shot data, one can use inversion based on simplified ray-tracing even for moderate-to-strong anisotropic models. When there are no perforation shots, event-location errors may become too large for moderately anisotropic media.

KW - Microseismic monitoring

KW - multicomponent data

KW - passive seismic inversion

KW - seismic anisotropy

KW - transverse isotropy

KW - SEISMIC ANISOTROPY

KW - VELOCITY

KW - FIELD

UR - http://www.scopus.com/inward/record.url?scp=85076370554&partnerID=8YFLogxK

U2 - 10.1111/1365-2478.12906

DO - 10.1111/1365-2478.12906

M3 - Article

AN - SCOPUS:85076370554

VL - 68

SP - 918

EP - 925

JO - Geophysical Prospecting

JF - Geophysical Prospecting

SN - 0016-8025

IS - 3

ER -