Are bright spots always hydrocarbons? A case study in the Taranaki Basin, New Zealand

Reilly, Peter J.; Clairmont, Roberto; Bedle, Heather

doi:10.1190/int-2020-0047.1

Cited by 2 publications

(1 citation statement)

References 26 publications

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“…The sweetness attribute is a division of the trace envelope by the square of the instantaneous frequency [49]. It is a useful attribute for delineating sand-confined channels [50][51][52] as well as a good indicator of hydrocarbon reservoirs correlating to bright spots [46,53]. Here, sweetness is also used to better resolve the BSR.…”

Section: Seismic Attribute Application: Frequency Attributesmentioning

confidence: 99%

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

et al. 2021

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Identifying gas hydrates in the oceanic subsurface using seismic reflection data supported by the presence of a bottom simulating reflector (BSR) is not an easy task, given the wide range of geophysical methods that have been applied to do so. Though the presence of the BSR is attributed to the attenuation response, as seismic waves transition from hydrate-filled sediment within the gas hydrate stability zone (GHSZ) to free gas-bearing sediment below, few studies have applied a direct attenuation measurement. To improve the detection of gas hydrates and associated features, including the BSR and free gas accumulation beneath the gas hydrates, we apply a recently developed method known as Sparse-Spike Decomposition (SSD) that directly measures attenuation from estimating the quality factor (Q) parameter. In addition to performing attribute analyses using frequency attributes and a spectral decomposition method to improve BSR imaging, using a comprehensive analysis of the three methods, we make several key observations. These include the following: (1) low-frequency shadow zones seem to correlate with large values of attenuation; (2) there is a strong relationship between the amplitude strength of the BSR and the increase of the attenuation response; (3) the resulting interpretation of migration pathways of the free gas using the direct attenuation measurement method; and (4) for the data analyzed, the gas hydrates themselves do not give rise to either impedance or attenuation anomalies that fully differentiate them from nearby non-hydrate zones. From this last observation, we find that, although the SSD method may not directly detect in situ gas hydrates, the same gas hydrates often form an effective seal trapping and deeper free gas accumulation, which can exhibit a large attenuation response, allowing us to infer the likely presence of the overlying hydrates themselves.

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Section: Seismic Attribute Application: Frequency Attributesmentioning

confidence: 99%

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

et al. 2021

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Simultaneous prediction of the geofluid and permeability of reservoirs in prestack seismic inversion

Yang,

Zong,

Sun

2024

GEOPHYSICS

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Geofluid discrimination and permeability prediction are indispensable steps in reservoir evaluation. From the perspective of pre-stack seismic inversion, predicting fluid indicators is an effective method for obtaining fluid properties directly from seismic data. In contrast, the direct prediction of permeability from observed seismic gathers is constrained by the difficulty in establishing a link between permeability and elastic parameters. However, we show that the pore structure parameters in seismic petrophysical theory are highly related to permeability, providing a new solution for predicting permeability using seismic data. Therefore, the correlation between the shear flexibility factor and permeability is first verified based on logging curves and laboratory data, and the results demonstrate that the shear flexibility factor can give an indicator of reservoir permeability. Secondly, an approximate reflection coefficient equation is derived for the direct characterization of the shear flexibility factor. In the proposed equation, a novel fluid indicator, expressed as the ratio of Russells fluid indicator to the square of the shear flexibility factor, is defined for the simultaneous prediction of fluid types and permeability. With the validated response of the novel fluid indicator to geofluid types, we achieve simultaneous predictions of fluid types and reservoir permeability characteristics from pre-stack seismic data, employing a boundary-constrained Bayesian inversion strategy. The model tests and the application on field data from a clastic reservoir confirm the effectiveness and applicability of the method.

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Are bright spots always hydrocarbons? A case study in the Taranaki Basin, New Zealand

Cited by 2 publications

References 26 publications

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

Simultaneous prediction of the geofluid and permeability of reservoirs in prestack seismic inversion

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