Accuracy of microseismic event locations recorded with single and distributed downhole sensor arrays

Zimmer, Ulrich; Bland, Henry C.; Du, Jing; Warpinski, N.R.; Sen, Vikram; Wolfe, Jim

doi:10.1190/1.3255137

Cited by 12 publications

(3 citation statements)

References 2 publications

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“…1 are a lower bound and this was also confirmed by the comparison in the case study. This conclusion is also supported by recently published studies (Maxwell 2009; Zimmer 2009) that take the 1D heterogeneity into account and found large radial and vertical errors (exceeding 100 m in realistic models). Our case study shows that surface and downhole microseismic monitoring have a similar order of uncertainty in the vertical direction, indicating that surface locations standard deviation of 4 ms is more representative than 10 ms.…”

Section: Discussionsupporting

confidence: 80%

Comparison of surface and borehole locations of induced seismicity

Eisner¹,

Hulsey²,

Duncan³

et al. 2010

Geophysical Prospecting

181

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Small Microseismic Surface Acquisition System for oilfield monitoring is presented. Algorithms for data processing are based on the mathematical theory of inverse problems and the using of the supercomputer calculations. A distinctive feature of the suggested system is high mobility, compactness and universality. The technology based on the this acquisition system is intended not only for hydraulic fracturing monitoring but also for long-duration passive monitoring of fluid injection, for hydrocarbon drainage area estimation and for oilfield block structure mapping. Case Study has more than 50 examples.

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Section: Discussionsupporting

confidence: 80%

Comparison of surface and borehole locations of induced seismicity

Eisner¹,

Hulsey²,

Duncan³

et al. 2010

Geophysical Prospecting

181

View full text Add to dashboard Cite

show abstract

“…Reliable locations of microseismic events are a key factor of successful monitoring of shale gas hydraulic stimulation (e.g., Eisner et al, 2009;Zimmer et al, 2009). To obtain them it is necessary to have a calibrated velocity model (Zhang et al, 2013;Yu, 2016), which in many real https://mc.manuscriptcentral.com/interpretation Interpretation 1 2 3 4 5 6 7 8 9…”

Section: Introductionmentioning

confidence: 99%

Results of downhole microseismic monitoring at a pilot hydraulic fracturing site in Poland — Part 2: S-wave splitting analysis

2018

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Observations of azimuthal seismic anisotropy provide useful information, notably on stress orientation and the presence of preexisting natural fracture systems, during hydraulic fracturing operations. Seismic anisotropy can be observed through the measurement of S-wave splitting (SWS) on waveforms generated by microseismic events and recorded on downhole geophone arrays. We have developed measurements of azimuthal anisotropy from a Lower Paleozoic shale play in northern Poland. The observed orthorhombic anisotropic symmetry system is dominated by a vertically transverse isotropy (VTI) fabric, produced by the alignment of anisotropic platy clay minerals and by thin horizontal layering and overprinted by a weak azimuthal anisotropy. Despite the dominating VTI fabric, we successfully identified a weaker horizontal-transverse isotropy fabric striking east–southeast. We do this by constraining the rock-physics model inversion with VTI background parameters incorporated from other geophysical methods: microseismic velocity model inversion, 3D reflection seismic, and borehole cross-dipole sonic logs. The obtained orientation is consistent with a preexisting natural fracture set that has been observed using X-ray micro-imaging (XRMI) image logs from a nearby vertical well. The present-day regional maximum horizontal stress direction differs from the observed fracture strike by approximately 45°. This implies that the SWS measurements recorded during hydraulic stimulation of a shale-gas reservoir are imaging the preexisting natural fracture set, which influences the treatment efficiency, instead of the present-day stress.

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“…Microseismic monitoring is an important diagnostic tool for hydraulic fracturing stimulation in unconventional reservoirs (Grechka, 2010;Maxwell et al, 2010;Li et al, 2019b;Pan et al, 2022). Locating induced microseismic events is the primary task in such monitoring, which requires the accurate velocity model (Eisner et al, 2009;Zimmer et al, 2009;Li et al, 2020). Traditionally, the velocity models are derived from sonic logs and perforation shots (Pei et al, 2009;Bardainne and Gaucher, 2010).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis of anisotropic parameter inversion simultaneously with microseismic source location in layered VTI media

Zheng

Wang²

2022

Front. Earth Sci.

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The hypocenters of microseismic events induced by hydraulic fracturing are conventionally located with an initial model established from well logs or perforation shots. In most geological settings, the arrival times are insufficiently explained without accounting for the velocity changes introduced by the reservoir stimulation process. The model parameters and source locations should be inverted simultaneously with arrival time information. Therefore, the joint inversion of event locations and velocity model requires the information of anisotropy parameters, which leads to the problem of the selection of degree of symmetry of anisotropic media in the inversion process. Since it is not possible to retrieve all elastic moduli from limited passive seismic data, the joint inversion is constrained to layered vertical transversely isotropic (VTI) media. Various methods have been proposed to invert the velocity model and source locations from the arrival times in anisotropic media, but the number of retrievable parameters in different parametrization types and acquisition scenarios have not been decisively discussed. We analyze the sensitivities for event locations and anisotropic parameters by the singular value decomposition (SVD) of the Fréchet derivatives in a layered anisotropic medium with vertical axis of symmetry. The singular values and eigenvectors obtained from SVD can be used to predict which unknown parameters are better constrained by the available traveltimes. The comparison of different parametrizations and monitoring array configurations allows to design a better inversion strategy to provide microseismic event locations and anisotropic parameters.

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Accuracy of microseismic event locations recorded with single and distributed downhole sensor arrays

Cited by 12 publications

References 2 publications

Comparison of surface and borehole locations of induced seismicity

Comparison of surface and borehole locations of induced seismicity

Results of downhole microseismic monitoring at a pilot hydraulic fracturing site in Poland — Part 2: S-wave splitting analysis

Sensitivity analysis of anisotropic parameter inversion simultaneously with microseismic source location in layered VTI media

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