A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

Xiao, Kun; Zou, Changchun; Yang, Yuanheng; Zhang, Hua; Li, Hongxing; Qin, Zhihong

doi:10.1002/ese3.569

Cited by 5 publications

(3 citation statements)

References 48 publications

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“…Previous studies have shown that the seawater depth, geothermal gradient, and BWT are all important factors influencing the GHSZ (Collett, 2009). In these previous studies, the relationship between the parameters and the thickness of the GHSZ was determined by ansatze method (Paull et al, 1991;Milkov and Sassen, 2003;Wang and Lau, 2020) or linear correlation coefficient analysis (Wang et al, 2017b;Xiao et al, 2020). Then the influence of the parameters changes on the dynamic accumulation of hydrate was obtained.…”

Section: Main Factors Affecting the Thickness Changes Of The Ghszmentioning

confidence: 99%

Spatial-temporal variations of the gas hydrate stability zone and hydrate accumulation models in the Dongsha region, China

Song

Lei²,

Zhang³

et al. 2022

Front. Mar. Sci.

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It is of great significance to study the spatial-temporal variations of the thickness of the gas hydrate stability zone (GHSZ) to understand the decomposition, migration, accumulation and dissipation of gas hydrate, the corresponding relationship between bottom-simulating reflectors (BSRs) and gas hydrate, and the distribution of heterogeneous gas hydrate. We selected the Dongsha region in the South China Sea (SCS) as the research object to calculate the spatial-temporal variation of the GHSZ since 10 Ma, analyzed the main factors affecting the thickness of the GHSZ, discussed the dynamic accumulation processes of gas hydrate, and proposed an accumulation model of gas hydrate in the Dongsha region. The results show that the thicknesses of the GHSZ in the study area were between 0 m and 100 m from 10 to 5.11 Ma, and the relatively higher bottom water temperature (BWT) was the key factor leading to the thinner thickness of the GHSZ during this period. From 5.11-0 Ma, the thickness of the GHSZ gradually increased but showed several fluctuations in thickness due to changes in the geothermal gradient, seawater depth, BWT, and other factors. The decrease in the BWT was the main factor leading to GHSZ thickening from 5.11 to 0 Ma. The thicknesses of the GHSZ are between 110 m and 415 m at present. The present spatial distribution features show the following characteristics. The GHSZ in the deep canyon area is relatively thick, with thicknesses generally between 225 m and 415 m, while the GHSZ in other areas is relatively thin, with thicknesses between 110 m and 225 m. Based on the characteristics of the GHSZ, two hydrate accumulation models are proposed: a double-BSRs model due to thinning of the GHSZ and a multilayer hydrate model due to thickness changes of the GHSZ, with single or multiple BSRs.

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Section: Main Factors Affecting the Thickness Changes Of The Ghszmentioning

confidence: 99%

Spatial-temporal variations of the gas hydrate stability zone and hydrate accumulation models in the Dongsha region, China

Song

Lei²,

Zhang³

et al. 2022

Front. Mar. Sci.

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“…Natural gas hydrates remain stable under suitable temperature and pressure conditions, forming a phase equilibrium curve. The phase equilibrium curve of the methane hydrate was calculated according to Colorado School of Mines Hydrate Kinetics model (Tsuji et al, 2005;Sloan Jr et al, 2007;Babakhani et al, 2015;Xiao et al, 2020), as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Parameters optimization of storage capacity of hole-bottom freezing sampling technique for natural gas hydrates

Lei,

Guo,

Yang

et al. 2024

Adv. Geo-Energy Res.

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The coolant must be pre-stored in the sampler before the freezing procedure for natural gas hydrate sampling is applied. The coolant's storage capacity throughout the samplerlowering procedure is crucial to ensure successful sampling. In this study, the key factors influencing storage capacity were coolant density, dry ice specific surface area, ambient pressure, and temperature difference. An orthogonal method was used to analyze each factor's level of influence and potential action processes. The results indicated that ambient pressure, specific surface area, coolant density, and temperature difference all had significant impact. Ambient pressure affects the phase-change path of dry ice, and high pressure increases the likelihood of dry ice melting, greatly reducing latent heat. The larger specific surface area could help to generate a compact dry ice layer to protect the interior, but it may cause cold energy loss during the freezing process. Dry ice, with a smaller specific surface area, may be a better option. Low-temperature alcohol can separate the dry ice layer from the surrounding environment, allowing for heat exchange. However, a low coolant density may promote heat exchange between the alcohol layer and surrounding environment, resulting in the loss of dry ice. The appropriate coolant formulation comprised of a mixture of 2.5 kg of granular dry ice and 1 L of alcohol, temperature difference maintained at 105 K, and the working pressure of 0.1 MPa.

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“…Furthermore, previous studies indicate that different gas components influence the temperature-pressure phase equilibrium curve of gas hydrate and further affect the thickness of gas hydrate stability zone (GHSZ) (Trehu AM et al, 2006;Sloan et al, 2010). Hydrates containing heavy hydrocarbon gas may be more thermodynamically stable, so that molecular composition may provide extra clues for hydrate distribution (Xiao et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Geochemical characteristics of gases associated with natural gas hydrate

Chang

2022

Front. Mar. Sci.

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With more natural gas hydrate samples recovered and more research approaches applied to hydrate-associated gas studies, data concerning the geochemical characteristics of hydrate-associated gases have been increased significantly in the past decades. Although systematic reviews of hydrocarbons are available, fewer studies have focused on the systematic classification of gas hydrates, yet. In this study, the primary origins and secondary processes that affect the geochemical characteristics of the gases are discussed. The primary origins are affected mainly by the type and /or maturity of the organic matter, which determine the main signature of the gas is microbial gas or thermogenic gas in a broad scheme. Apart from primary origins, secondary processes after gas generation such as migration, mixing, biodegradation and oxidation occur during the migration and/or storage of gases can significantly alter their primary features. Traditional methods such as stable isotope and molecular ratios are basic proxies, which have been widely adopted to identify these primary origins and secondary processes. Isotopic compositions of C2+ gases have been employed to identify the precursor of the gases or source rocks in recent years. Data from novel techniques such as methane clumped isotope and noble gases bring additional insights into the gas origins and sources by providing information about the formation temperature of methane or proxies of mantle contribution. A combination of these multiple geochemical approaches can help to elucidate an accurate delineation of the generation and accumulation processes of gases in a gas hydrate reservoir.

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A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

Cited by 5 publications

References 48 publications

Spatial-temporal variations of the gas hydrate stability zone and hydrate accumulation models in the Dongsha region, China

Spatial-temporal variations of the gas hydrate stability zone and hydrate accumulation models in the Dongsha region, China

Parameters optimization of storage capacity of hole-bottom freezing sampling technique for natural gas hydrates

Geochemical characteristics of gases associated with natural gas hydrate

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