Quantitative estimation of overpressure caused by gas generation and application to the <scp>B</scp>aiyun <scp>D</scp>epression in the <scp>P</scp>earl <scp>R</scp>iver <scp>M</scp>outh <scp>B</scp>asin, <scp>S</scp>outh <scp>C</scp>hina <scp>S</scp>ea

Guo, Xiaowen; Liu, K. Y.; He, Shunli; Zhi, Yang; Dong, Tian

doi:10.1111/gfl.12140

Cited by 21 publications

(5 citation statements)

References 27 publications

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“…Not only in areas with high structural relief, but also in low-relief deltaic environments, compaction disequilibrium may cause large pressure compartmentalization, leading to undercompacted shales that exhibit high overpressures [51,52]. Hydrocarbon generation (with fluid or gas expansion) has been described as a pressure generator [53], and diagenesis (clay smectite-illite transformation), tectonic compression, and pressure transfer can all play important roles. Finally, the advancement and retreat of thick ice sheets during transitions between glaciation and inter-glaciation periods also lead to changes in effective stress and pore pressures between units of different compressive strength [54][55][56][57].…”

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confidence: 99%

Sealing of a Deep Horizontal Borehole Repository for Nuclear Waste

Finsterle¹,

Cooper

Muller

et al. 2020

Energies

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The depth and layout of a horizontal borehole repository has the potential to offer strong isolation of nuclear waste from the surface. However, the isolation may be compromised by the borehole used to access the repository, as it could provide a direct fast-flow path transporting radionuclides from the disposal section to the accessible environment. Thus, backfilling the disposal section and sealing the access hole are considered essential engineered safety components. To analyze the importance of plugging the open space between canisters and sealing the access hole, we numerically calculate non-isothermal fluid flow and radionuclide transport through the borehole and the surrounding geosphere for a variety of scenarios, which include backfill materials with different sealing properties and configurations that potentially induce strong driving forces along both the horizontal and vertical sections of the borehole. The simulations indicate that the dose contribution of radionuclides released through the access hole is small, even if the backfill material is of poor quality or has deteriorated, and even if considerable horizontal and vertical pressure gradients are imposed by assuming the underlying formation is overpressured and that the disposal section is intersected by faults activated during a seismic event. The modeling also reveals that the low influence of backfill integrity on repository performance partly arises from the very high length-to-diameter ratio of the borehole, which favors the radial diffusion of radionuclides—as well as pressure dissipation and associated advective transport—into the surrounding formation rather than axial transport along the borehole. The integrated modeling approach also exposes the importance of accounting for the connections and feedback mechanisms among the various subcomponents of the repository system.

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mentioning

confidence: 99%

Sealing of a Deep Horizontal Borehole Repository for Nuclear Waste

Finsterle¹,

Cooper

Muller

et al. 2020

Energies

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“…formation fluid pressure in deep natural gas reservoirs increases, resulting in overpressures. It is generally believed that the Dongsha movement is the trigger for the release of overpressures, which will lead to the migration of fluids (Guo et al, 2016;Kong et al, 2018). The Baiyun sag has been scientifically confirmed to possess a record of intermittent occurrences of overpressure events.…”

Section: Figure 12mentioning

confidence: 99%

Faults and gas chimneys jointly dominate the gas hydrate accumulation in the Shenhu Area, northern South China Sea

Ren,

Cheng,

Jiang

et al. 2023

Front. Mar. Sci.

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Gas hydrates possess significant potential as an energy resource and exert a notable influence on global climate change. The Shenhu Area is one of the globally recognized focal points for gas hydrate research, and additional investigation is required to fully comprehend its gas migration mechanism. By utilizing the most recent core-log-seismic data and gas geochemical data, a comprehensive analysis was conducted to determine the influence of gas migration pathways on gas hydrate accumulation in the study area. This study investigated the various types of gas migration pathways, employing integrated geological models that incorporate faults and gas chimneys to understand their respective contributions to the accumulation of gas hydrates. Based on these findings and drilling constraints, a three-gas combined production model was subsequently proposed. Thermogenic gas, secondary microbial gas, and in situ microbial gas are all potential sources of the gas responsible for hydrate formation. Thermogenic gas plays a significant role in the gas hydrate system, as evidenced by distinct features of late-mature thermogenic gas observed in gas samples extracted from hydrates in Well W18. In the study area, the primary conduits for gas migration encompass deep faults, branch faults, and gas chimneys. Among these, deep faults act as the most crucial pathways of thermogenic gas migration. The integration of geological models that incorporating deep faults and gas chimneys has profoundly impacted the accumulation of gas hydrates in the Shenhu Area, consequently influencing the distribution of shallow gas and gas hydrate. Furthermore, the proposed three-gas combined production model, which involves the simultaneous extraction of deep gas reservoirs, shallow gas reservoirs, and gas hydrates, holds significant implications for exploring and developing deep-water natural gas resources. However, its successful implementation necessitates interdisciplinary collaboration among scientists.

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“…Magmatism in the Baiyun Sag reflects a progressive continental breakup, representing postrift tectonic thermal events associated with the continental breakup process [37]. Then, a Neotectonic movement called the Dongsha movement occurring since 13.8 Ma continuously made the faulting and thermal fluid activities more intense [48] and resulted in a number of gas chimneys and high-angle faults penetrated from the Paleogene to the Neogene strata in the Baiyun Sag, which are considered as the main migration channels for thermal fluids during the postrift stage, especially after 13.8 Ma [49][50][51]. Previous research on carbon, oxygen, and strontium isotopes of carbonate cements of sandstones in the Zhuhai Formation from the Baiyun Sag shows that the diagenetic fluids in the Zhuhai Formation are organic and inorganic mixed origin [45,46].…”

Section: Reservoirs In the Mgr And Hgr Were Affected Bymentioning

confidence: 99%

Impact of High Thermal Setting and Fluid Activities on Sandstone Compaction: A Case Study of the Baiyun Sag in the Pearl River Mouth Basin (Northern South China Sea)

Luo

Fan³

et al. 2021

Geofluids

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Compaction is regarded as central to the reduction of reservoir physical properties. The thermal compaction process controlled by a basin’s heat flow and the static compaction caused by overload on rocks are both important factors controlling the compaction strength. However, porosity loss resulting from thermal and static compaction has not been distinguished. The Baiyun Sag in the Pearl River Mouth Basin in the northern part of the South China Sea with high heat flows and a variable geothermal gradient is an ideal setting for studying the characteristics and mechanisms of the thermal compaction process. The characteristics of compaction and the effect of thermal fluid activities on reservoir physical properties are carried out, based on the observation and identification of sandstone thin sections under a microscope, the measurement and simulation of the temperatures and trapping pressures of fluid inclusions, and the calculation of the compaction porosity loss as well. The result shows that the compaction mode of sandstone reservoirs in the Zhuhai Formation is dominated by static compaction in the LGR (the low geothermal gradient region), whereas the diagenetic process of the Zhuhai Formation in the MGR (the moderate geothermal gradient region) and HGR (the high geothermal gradient region) is affected not only by the static compaction effect but also by the thermal compaction effect caused by abnormal formation temperature and pressure conditions. The porosity loss caused by the thermal compaction ranges from 5.5% to 11.2% with an average of 7.9% and from 4.6% to 16.6% with an average of 10.2% in the MGR and HGR, respectively. The porosity loss caused by the static compaction ranges from 15.9% to 20.8% with an average of 19.4% and from 8.4% to 15.8% with an average of 12.8% in the MGR and HGR, respectively.

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Quantitative estimation of overpressure caused by gas generation and application to the Baiyun Depression in the Pearl River Mouth Basin, South China Sea

Cited by 21 publications

References 27 publications

Sealing of a Deep Horizontal Borehole Repository for Nuclear Waste

Sealing of a Deep Horizontal Borehole Repository for Nuclear Waste

Faults and gas chimneys jointly dominate the gas hydrate accumulation in the Shenhu Area, northern South China Sea

Impact of High Thermal Setting and Fluid Activities on Sandstone Compaction: A Case Study of the Baiyun Sag in the Pearl River Mouth Basin (Northern South China Sea)

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