Seismic attributes for characterizing gas hydrates: a study from the Mahanadi offshore, India

Kumar, Jitender; Sain, Kalachand; Arun, K.P.

doi:10.1007/s11001-018-9357-4

Cited by 19 publications

(10 citation statements)

References 54 publications

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“…We apply the instantaneous frequency and sweetness attributes to highlight such disadvantages. It is important to reiterate that many studies have shown the benefits of seismic attributes, especially sweetness and instantaneous frequency, to assess gas hydrate and free gas presence [46][47][48], and that this study compares the differences among several methods based on the results. We use IF to resolve the trends of the BSR and indirectly observe attenuation effects in the seismic.…”

Section: Seismic Attribute Application: Frequency Attributesmentioning

confidence: 99%

“…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%

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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%

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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“…We use the general term "seismic attributes" in this manuscript. A detailed description of the main attributes and their mathematical expressions can be found elsewhere (e.g., Taner et al, 1979;Coren et al, 2001;Kumar et al, 2019). Today, there are several different types of seismic attributes used for different purposes at different stages of seismic interpretation.…”

Section: Seismic Attribute Analysismentioning

confidence: 99%

“…Seismic attributes are often used to analyze and obtain some additional information from BSR reflections by several researchers (e.g., Taylor et al, 2000;Coren et al, 2001;Satyavani et al, 2008;Lee et al, 2017;Kumar et al, 2019). In this study, we calculate seven different seismic attributes to characterize the BSR reflections.…”

Section: Seismic Attribute Analysismentioning

confidence: 99%

“…Complex trace seismic attribute analysis is a useful tool to analyze the free gas and gas hydrate accumulations as it can reveal the seismic imprints of these structures because of the above-mentioned characteristics of the gas hydrates and underlying free gas (e.g., Taylor et al, 2000;Coren et al, 2001;Satyavani et al, 2008;Lee et al, 2017;Kumar et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Seismic identification of gas hydrates: A case study from Sakarya Canyon, western Black Sea

Nasıf

Özel

Dondurur

2020

Turkish J Earth Sci

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Multichannel seismic, 3.5-kHz Chirp subbottom profiler and multibeam bathymetric data were collected along the western Black Sea margin, offshore Sakarya River, to investigate the bottom-simulating reflections (BSRs), free gas accumulations, and mud volcanoes. Geometries from the seismic data indicate widespread BSRs along the continental rise between 750 and 1950 m water depths, 70 to 350 ms below the seafloor. Seismic attribute analyses have been applied to the seismic data to reveal the acoustic properties of the gas hydrates. According to the results from such analyses, we conclude that there are acoustically transparent zones beneath most of the BSRs in the area, which are interpreted as free gas accumulations, and the gas hydrate-bearing sediments are acting as seals for the free gas in the underlying sediments. Stability analysis of the gas hydrates from different BSR zones in the area suggests that the gas composition in the gas hydrates may change locally. As we do not have ground truth data from BSR zones, the exact composition of the gas forming the gas hydrates is unknown. However, hydrocarbon productivity of the area, chromatography results of the shallow sediment samples nearby, and stability analysis of the gas hydrates indicate the possible existence of a thermogenic gas component in the gas hydrate composition, resulting in a mixture of gas hydrates.

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Delineation of oil–water contact within Tipam reservoir: A study from Upper Assam Basin, North‐East India

Kumar

Sain

2023

Geological Journal

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Fluid contacts within a reservoir can vary either because of compartmentalization by faults, lithological variations, hydrocarbon fill history or changes in the hydrodynamic activity of fluids. Their detailed interpretation is significant for estimating potential reserves and developing an explored hydrocarbon field. This study uses high‐quality three‐dimensional (3D) seismic reflection data to decipher the fluid contact zones and their types from the well‐known Tipam reservoir in the petroliferous Upper Assam foreland basin. Different seismic attributes are used to understand the seismic response of fluids and associated structures that structurally control the reservoir geometry. Fluid contact analysis is performed by amalgamating these responses within the target interval. The analysis indicates that the south‐west part of the reservoir is a promising hydrocarbon‐bearing zone and consists of oil–water contacts. These contacts possess a dominant trend of NE–SW within the reservoir. Further, a decreasing trend in the density, velocity and an increasing trend in the resistivity and porosity logs of the wellbore SC‐2 calibrates these inferences and confirms the presence of oil‐bearing zones underlain by water in the SW part of the Tipam reservoir. Thus, the Upper Assam foreland basin is a promising area for hydrocarbon exploration, in which Mid‐Miocene sequences are the potential leads that can be unlocked. The analysis presented through this research could be efficiently and similarly carried out in onshore basins worldwide.

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Seismic attributes for characterizing gas hydrates: a study from the Mahanadi offshore, India

Cited by 19 publications

References 54 publications

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

Seismic Attribute Analyses and Attenuation Applications for Detecting Gas Hydrate Presence

Seismic identification of gas hydrates: A case study from Sakarya Canyon, western Black Sea

Delineation of oil–water contact within Tipam reservoir: A study from Upper Assam Basin, North‐East India

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