Improvement of local anisotropy estimation from VSP data through experimental design

Barreto, Adriano C. R.; Gomes, Ellen N. S.; Macambira, R N A; Costa, Jessé C.

doi:10.1088/1742-2132/10/4/045008

Cited by 3 publications

(14 citation statements)

References 11 publications

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“…In this study, the authors analyze the dependence of this inversion scheme on factors such as the degree of anisotropy, the noise level of the slowness and polarization data, the type of wave used (direct and/or reflected P-waves), the choice of anisotropic parameters for the medium and its degree of heterogeneity. This provides continuation for the analysis presented in Barreto et al (2013). A similar analysis can be found in Rusmanugroho & McMechan (2012); however, this work differs from the Rusmanugroho's study both methodology and the type of wave used in the inversion.…”

Section: Introductionsupporting

confidence: 73%

“…1) and the parameters of the reference isotropic medium. This dependency is analyzed in detail in Barreto et al (2013), where it is shown that to uniquely estimate the 15 WA parameters, the surface sources must be distributed on both sides of the well in at least five regularly spaced profiles. In this study, the data were acquired in six regularly spaced profiles spanning 0…”

Section: Sensitivity Matrixmentioning

confidence: 99%

“…The many ways to determine these parameters are presented in Barreto et al (2013). In this study, the reference isotropic medium's parameters were chosen based solely on the observed data.…”

Section: The Inverse Problemmentioning

confidence: 99%

“…In studies such as Horne & Leaney (2000); Zheng & Pšenčík (2002); Gomes et al (2004); Rusmanugroho & McMechan (2012);and Barreto et al (2013), the anisotropic parameters of a medium are estimated by inversion of P-wave (or P-and Swave) slowness and polarization data measured in vertical seismic profile (VSP) surveys.…”

Section: Introductionmentioning

confidence: 99%

“…Using this methodology and considering only the vertical component of the P-waves' slowness and polarization vectors from a single VSP profile, Gomes et al (2004) estimated the anisotropy using data from a region of the Java Sea. Barreto et al (2013) estimated the anisotropy by studying the experimental design of multi-azimuth walkaway VSP surveys. This inversion scheme does not depend on the structure of the medium above the geophone (it can be homogeneous or heterogeneous), nor does it depend on the shape of the well (it can be directional or curved, vertical or sloped).…”

Section: Introductionmentioning

confidence: 99%

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Analysis of a Linear Scheme for Estimation of Local Anisotropy From P-Wave Data in Multi-Azimuth VSP Surveys

Macambira¹,

Gomes²,

Barreto³

2014

Rev. Bras. Geof.

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ABSTRACT. This study presents an analysis of the linear inversion scheme for estimating anisotropy in the neighborhood of a receiver placed in a well using the vertical components of the slowness and polarization vectors of P-waves measured in multi-azimuth walkaway vertical seismic profile (VSP) surveys. Independently of the medium above the geophone (homogeneous or heterogeneous) and the shape of the well (directional or curved, vertical or sloped), an inversion is performed from a first-order approximation around a reference isotropic medium. The analysis of the inversion scheme considers factors such as the noise level of the data, the type of P-wave, the degree of the anisotropy of the medium, the choice of parameters in the reference isotropic medium and the degree of heterogeneity of the medium.Keywords: anisotropy estimation, multi-azimuth walkaway VSP data, weak anisotropy. RESUMO.Neste trabalhoé apresentada uma análise do esquema de inversão linear para a estimativa de anisotropia na vizinhança de um receptor situado em um poço a partir da componente vertical do vetor de vagarosidade e do vetor de polarização das ondas P medidos em experimentos de VSP walkaway multiazimutal. Independente do meio acima do geofone (homogêneo ou heterogêneo) e da geometria do poço (inclinado, reto ou curvo), a inversãoé feita a partir de uma aproximação de primeira ordem em torno de um meio isotrópico de referência. O esquema de inversãoé analisado considerando diferente fatores, tais como: nível de ruído nos dados, tipo de onda P, grau de anisotropia do meio, escolha dos parâmetros no meio isotrópico de referência e grau de heterogeneidade do meio.Palavras-chave: estimativa de anisotropia local, dados de VSP walkaway multiazimutal, fraca anisotropia.

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Section: Introductionsupporting

confidence: 73%

Section: Sensitivity Matrixmentioning

confidence: 99%

Section: The Inverse Problemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Analysis of a Linear Scheme for Estimation of Local Anisotropy From P-Wave Data in Multi-Azimuth VSP Surveys

Macambira¹,

Gomes²,

Barreto³

2014

Rev. Bras. Geof.

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Estimativa de anisotropia em poços direcionais

Pereira¹,

Silva²,

Gomes³

2019

Proceedings of the 16th International Congress of the Brazilian Geophysical Society&Expogef

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Local Anisotropy Estimation From Qp-Wave VSP Data: Analysis of 3d Survey Design

Silva¹,

Gomes²

2019

Braz J Geophys

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ABSTRACT. In the world, many unconventional hydrocarbon reservoirs have been found. This type of reservoir generally has anisotropic properties. The estimation of the anisotropy of the medium can give useful information about the reservoir, for example, one can obtain the information on the direction of fractures, these are related to the preferential flow. This information is important in deciding which direction to drill the well. Measurements of slowness and polarization of qP-wave obtained from VSP (vertical seismic profile) experiments allow estimating the anisotropy in the vicinity of a geophones inside the borehole. Using the perturbation theory, a weakly anisotropic medium can be modeled by first-order perturbation around an isotropic reference medium. The inversion scheme is based on a linear approximation which expresses the slowness and polarization in terms of WA (weak anisotropy) parameters. These parameters characterize the deviations of the anisotropic medium from a reference isotropic medium. In presented inversion scheme, we use the three components of the polarization, since we consider 3C (three-components) geophones, and only one of the slowness components, the one along the borehole direction, where is located the receiver array. In this work, the inversion scheme using VSP data of slowness and polarization from direct wave qP for the estimation of the parameters of weak anisotropy WA is analyzed considering the orientation of the horizontal borehole. Three different configurations for the sources are analyzed. The results are compared with results from vertical borehole. It has been found that only a group of components of the tensor of the WA parameters is well estimated and this group depend on the orientation of the borehole. On the other hand, the phase velocity determined from the WA parameter tensor is always well estimated in a 30_ cone around the borehole, regardless of the borehole orientation.Keywords: Local anisotropy, VSP multiazimuthal, linear inversion, survey design.RESUMO. Muitos reservatórios de hidrocarbonetos não convencionais tem sido encontrados. Esse tipo de reservatório geralmente tem propriedades anisotrópicas. A estimativa da anisotropia do meio pode fornecer informações úteis sobre o reservatório, como por exemplo, informações sobre a direção das fraturas que estão relacionadas a direção de fluxo preferencial. Esta informação é importante para decidir que direção furar o poço. Medidas de vagarosidade e polarização de ondas qP obtidas em levantamentos de VSP (vertical seismic profile) permitem estimar a anisotropia na vizinhança de um geofone dentro do poço. Usando a teoria da perturbação, um meio fracamente anisotrópico pode ser modelado como uma perturbação de primeira ordem em torno de um meio isotrópico de referência. O esquema de inversão baseia-se numa aproximação linear que expressa a vagarosidade e polarização em termos do parâmetros WA (fraca anisotropia). Esses parâmetros caracterizam os desvios do meio anisotrópico a partir de um meio isotrópico de referência. No esquema de inversão são usadas as três componentes do vetor de polarização, esta-se considerando geofones 3C (três componentes) e apenas uma componente do vetor de vagarosidade, a componente ao longo da direção de orientação do poço, onde estão localizados os receptores. Neste trabalho, é analisado o esquema de inversão são usados dados de vagarosidade e polarização de ondas qP diretas em experimentos de VSP considerando a orientação do poço horizontal. Três diferentes configurações para as fontes são estudadas. Os resultados foram comparados com os resultados obtidos considerando o poço vertical. Verifica-se que apenas um grupo de componentes do tensor dos parâmetros elásticos WA é bem estimado. Este grupo depende da orientação do poço. Por outro lado, a velocidade de fase determinada a partir dos parâmetros WA é sempre bem estimada em um cone de 30_ torno do poço, independente de sua orientação. Palavras-chave: Anisotropia Local, VSP multiazimutal, inversão linear, desenho de experimento.

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Improvement of local anisotropy estimation from VSP data through experimental design

Cited by 3 publications

References 11 publications

Analysis of a Linear Scheme for Estimation of Local Anisotropy From P-Wave Data in Multi-Azimuth VSP Surveys

Analysis of a Linear Scheme for Estimation of Local Anisotropy From P-Wave Data in Multi-Azimuth VSP Surveys

Estimativa de anisotropia em poços direcionais

Local Anisotropy Estimation From Qp-Wave VSP Data: Analysis of 3d Survey Design

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