Towards a better seismic to well tie in complex media

Allouche, Hassan; Thore, P.; Monnerie, Thomas

doi:10.1190/1.3255220

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…Note that standard well-tie analysis is a highly interpretive process that relies on many assumptions that are often not satisfied in practice (Allouche et al, 2009). In addition, different water velocity conditions between checkshot and seismic surveys create unaccounted timeshifts manifested as poor well ties (Bakulin at el., 2010).…”

Section: Well Mistiesmentioning

confidence: 99%

Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Bakulin¹,

Zdraveva²,

Lyons

2010

SEG Technical Program Expanded Abstracts 2010

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Anisotropic depth imaging with Vertical Transversely Isotropic (VTI) models has become dominant in the industry.However, anisotropic parameters for these models continue to be derived by very basic practices without use of tomography. Hanging a single profile of Thomsen parameters from the water bottom still remains the most common practice. In a simple structural setting, it is usually possible to focus the data and obtain a good image despite having a simple and unrealistic model for Thomsen parameters. However, depth positioning of such images is usually suboptimal. Better positioning requires more geologically plausible models. In addition, imaging in complex settings may require Tilted Transversely Isotropic (TTI) models. In this case study we construct several anisotropic models using approaches with increasing complexity and evaluate the model impact on image quality and ties to well data. We start with a "new default" model, where a single, smoothed, borehole-calibrated profile is hung from the water bottom, and then we progress to an "intermediate" model where a similar profile with more vertical details is propagated using major geological horizons. We finish with an "elaborate" model, where profiles from several wells are interpolated throughout the model using geologic horizons. We contrast all these models to an "old default" model derived without well calibration. We observe a generally steady improvement in well ties compared to the "old default" model, with the proportionally largest change coming from simple well calibration ("new default" model) and additional uplift coming from incorporating geologic horizons ("intermediate" model). Differences between "intermediate" and "elaborate" models are small, while switching to TTI models clearly helps resolve complex structures in dipping areas. IntroductionIt is well understood that seismic data do not constrain all parameters of an anisotropic velocity field. Therefore, Thomsen parameters are usually estimated from joint inversion of well and seismic data at borehole locations. Profiles derived at wells are extrapolated or interpolated throughout the volume and kept static; whereas, velocity is updated with tomography. It is a general expectation that more accurate and geologically plausible volumes of Thomsen parameters models may lead to better images and improved well ties. We apply different model building practices and quantify their impact on imaging and ties to well data.

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Section: Well Mistiesmentioning

confidence: 99%

Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Bakulin¹,

Zdraveva²,

Lyons

2010

SEG Technical Program Expanded Abstracts 2010

View full text Add to dashboard Cite

show abstract

“…It means to correlate the geological features with the corresponding seismic reflections. More importantly it plays an important role to estimate the seismic wavelet which is the fundamental part of seismic inversion (Allouche et al, 2009). All the available wells in the target area were calibrated with the specific 2D seismic lines which pass through the corresponding wells location.…”

Section: Seismic To Well Tie and Wavelet Estimationmentioning

confidence: 99%

Sweetness analysis of Lower Goru sandstone intervals of the Cretaceous age, Sawan gas field, Pakistan

Azeem¹,

Chun²,

Khalid³

et al. 2018

Episodes

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B and C sands of the Lower Goru Formation of Cretaceous are proven reservoirs in different parts of the Middle and Lower Indus Basin, Pakistan. Most of the discoveries in this basin have been made in structural traps. However, in Sawan gas field; structural inversion, deep burial depth and heterogeneity of reservoir intervals make it difficult to demarcate the sweetness zones through conventional seismic analysis. In this work, different data sets have been integrated through constrained sparse spike inversion to mark sweetness zones in B and C sands of this formation. C sand contains four sweetness zones; the main sweetness zone is located towards the east while three subtle sweetness zones were identified towards the west of Sawan fault. The location of producing and nonproducing wells within the sweetness and outside of sweetness zones confirms the credibility of this work. B sand includes three sweetness zones located towards the west of Sawan fault. Moreover, inverted porosity results not only show good agreement with the porosity log of blind well (Sawan-02) but also show good matching with the core porosities. Hence integration of different data sets leads to demarcate the accurate location, size and extent of the sweetness zones.

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Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Bakulin

Liu²,

Zdraveva³

et al. 2010

The Leading Edge

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Anisotropic depth imaging with ver-tical transversely isotropic (VTI) models has become the dominant practice in the industry. However, anisotropic parameters for these models continue to be derived by basic practices without the use of tomography. Hanging a single profile of Thomsen's parameters from the water bottom still remains the most common practice. In a simple structural setting, it is usually possible to focus the data and obtain a good image despite having a simple and unrealistic model for Thomsen's parameters. However, depth positioning of such images is usually suboptimal. Better positioning requires more geologically plausible models. In addition, imaging in complex settings may require tilted transversely isotropic (TTI) models.

show abstract

Towards a better seismic to well tie in complex media

Cited by 4 publications

References 7 publications

Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

Sweetness analysis of Lower Goru sandstone intervals of the Cretaceous age, Sawan gas field, Pakistan

Anisotropic model building with wells and horizons: Gulf of Mexico case study comparing different approaches

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