Estimation of seismic velocities and gas hydrate concentrations: A case study from the Shenhu area, northern South China Sea

Liu, Jie; Zhang, Jianzhong; Ma, Fei; Wang, Ming; Sun, Youbin

doi:10.1016/j.marpetgeo.2017.08.014

Cited by 26 publications

(7 citation statements)

References 52 publications

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“…69 Liu et al executed several inversion methods to estimate the seismic velocities and gas hydrate saturation in the Shenhu area. 70 Considering that the estimated spatial distribution is consistent with the results from sonic logging, resistivity data, 47 and drilling results at well SH2, this estimation method provides an effective tool for gas hydrate exploration without or with few drilling or logging data. The wireline logging data provided a more complete analysis of the gas hydrate saturations at each of the sites established during GMGS-1.…”

Section: Advances On Natural Gas Hydratesupporting

confidence: 69%

“…In fact, heat flow can be used to predict the bottom of the GHSZ, which can provide key information for the exploration and evaluation of hydrate reservoirs. , Xu et al analyzed the heat flow characteristics via multidiscipline data, and reveal the relationship between heat flow and gas hydrate occurrence . Liu et al executed several inversion methods to estimate the seismic velocities and gas hydrate saturation in the Shenhu area . Considering that the estimated spatial distribution is consistent with the results from sonic logging, resistivity data, and drilling results at well SH2, this estimation method provides an effective tool for gas hydrate exploration without or with few drilling or logging data.…”

Section: Advances On Natural Gas Hydrate Geological Features In the Scsmentioning

confidence: 87%

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Recent Advances on Natural Gas Hydrate Exploration and Development in the South China Sea

Jian-wu

2021

Energy Fuels

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Because of the urgency of energy transition for a net-zero society, the world’s gas demand is rapidly increasing. Natural gas hydrate (NGH) is regarded as the next alternate energy resource to meet the demand, thanks to its high energy density and enormous reserves. As two successful production trials and a series of relevant drilling expeditions were implemented in the northern slope of the South China Sea (SCS), it may now be the most promising district for NGH exploitation in the world. The objective of this work is to review the recent research advances on hydrate exploration status, reservoir geological features, hydrate-bearing sediment geophysical properties, and hydrate exploitation techniques related to the hydrate reservoirs in the SCS. Geological surveys, well logging and core sampling were performed and helped the analysis of hydrate occurrence, gas origin, and accumulation mechanism. It is inferred that both microgenic and thermogenic gas present in SCS hydrate reservoirs and the hydrate accumulation is primarily controlled by the structure of the gas chimney. The characteristics of high porosity, low permeability, weak diagenesis, weak strength, and complex hydrate dissociation behaviors of the gas hydrate-bearing sediments from the SCS determined that innovative exploitation approaches are required. Different well configurations and reservoir stimulation techniques were proposed to enhance the production efficiency and evaluated through simulation and laboratory experiments. As the NGH development process in the SCS progresses continuously, it attracts more and more research interests from academic and engineering communities. We are convinced that, with constant diligence and effort, China will achieve the goal of safe and efficient commercial exploitation in the near future.

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Section: Advances On Natural Gas Hydratesupporting

confidence: 69%

Section: Advances On Natural Gas Hydrate Geological Features In the Scsmentioning

confidence: 87%

Recent Advances on Natural Gas Hydrate Exploration and Development in the South China Sea

Jian-wu

2021

Energy Fuels

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“…The spectral inversion and acoustic impedance inversion results also confirm that the sediments over the BSRs are enriched in gas hydrates. These are analogous to the gas hydrate distribution in the Shenhu area, which was characterized using a similar inversion method (J. Liu, Zhang, Ma, Wang, & Sun, 2017). According to the above‐described inversion results (Figures 7 and 8), a 10–40 m thick gas hydrate reservoir should exist in the shelf break in our study area.…”

Section: Discussionmentioning

confidence: 97%

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Zhang

Deng

et al. 2021

Geological Journal

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Based on interpretation and inversion of high‐resolution seismic data, a previously undocumented occurrence of pore‐filled gas hydrates that are associated with a submarine canyon system was discovered in the shelf break of the north‐east Qiongdongnan Basin (QDNB) in the northern South China Sea (SCS). Continuous bottom simulating reflections (BSRs) were recognized in the submarine striking NW‐SE ridges along the shelf break. The two‐way travel times (TWTs) of the BSRs are about 200–250 ms below the sea floor and the burial depths are mapped at ~180–225 mbsf after time‐depth conversion. The distribution of the enhanced reflections (ERs) and acoustic blanking zone overlying the BSRs indicate possible pore‐filled gas hydrate enrichment. ERs have been commonly observed immediately below the BSRs, indicating the accumulation of free gas, which exhibits distinct amplitude versus offset (AVO) anomalies. The acoustic impedance inversion results show that the gas hydrate saturation is 20–50%, and the thickness of the gas hydrate‐bearing layers is usually ~10–40 m, with a maximum thickness of up to ~90 m in local regions. Large‐scale listric faults originating from the deep sag connect the hydrocarbon source region and the shallow gas hydrate stability zone (GHSZ) and act as migration pathways for biogenic gas and potentially thermogenic gas. In addition, hydrocarbons may also be transported into the GHSZ along the sidewalls of the canyon. Canyon incision is believed to cause the increase in the burial depth of the BSRs on the flank of the ridge toward the base of the channel and thereby to trap the hydrocarbons migrating along the sidewall in permeable beds due to the decrease in permeability caused by the gas hydrate accumulation, resulting in the occurrence of ERs immediately below the BSRs. It is speculated that in the channel‐levee system, the coarse‐grained sediments should be deposited within the GHSZ, and the reservoir's physical properties are conducive to the wide distribution and enrichment of pore‐filled gas hydrates in the shelf break of the northern QDNB.

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“…Schwalenberg et al (2020) used the correction equation with an argillaceous parameter to estimate the hydrate saturation in the Black sea. Liu et al (2017) compared the difference between the traditional Archie equation and the empirical correction equation, compared the theoretical value of saturation calculated by the two equations with the actual value obtained by drilling, and found that the resistivity method with clay correction can accurately predict hydrate saturation. The Archie's equation is used to calculate water saturation in the marine sediment (Archie, 1942).…”

Section: Hydrate Saturationmentioning

confidence: 99%

Saturation sensitivity and influencing factors of marine DC resistivity inversion to submarine gas hydrate

Qiu

Fu²,

Yang³

et al. 2022

Front. Earth Sci.

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The submarine gas hydrate usually exists in the sediment on the continental slope. The bottom simulating reflector on the reflected seismic was identified as the bottom of the hydrate stability zone. However, many BSRs may not find the hydrate’s effective storage and its underlying free gas in many places. It is essential to identify the saturation of the hydrate. The resistivity can be used to evaluate the hydrate’s porosity and saturation. The hydrate boasts a high resistance to the surrounding sediments. The sensitivity of the marine Direct Current resistivity method (DCR) to the high resistance of the sediment can be used to evaluate the saturation of the hydrate. We have assessed the sensitivity of various DCR array arrangements, towed depths, hydrate thicknesses, and saturation. These influencing factors for improving recognition ability were also systematically analyzed. We have compared the inversion results of various DCR array arrangements, as well as different depths, thicknesses, and hydrate saturation, and calculated the saturation. We suggest using the corrected saturation equation to analyze the DCR results, which can improve the ability of hydrate identification. Evaluating these parameters will help develop or select DCR instruments for detecting the submarine gas hydrate.

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Estimation of seismic velocities and gas hydrate concentrations: A case study from the Shenhu area, northern South China Sea

Cited by 26 publications

References 52 publications

Recent Advances on Natural Gas Hydrate Exploration and Development in the South China Sea

Recent Advances on Natural Gas Hydrate Exploration and Development in the South China Sea

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Saturation sensitivity and influencing factors of marine DC resistivity inversion to submarine gas hydrate

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