佳文速递｜2025年第2期

 Estimating gas hydrate saturation in sediments using geophysical methods

利用地球物理方法估算沉积物中的天然气水合物饱和度

发表时间：2025年5月8日

发表期刊：《Marine and Petroleum Geology》

 Linsen Zhan, Wenjiu Cai, Haotian Liu, Ran Yang, Shiyuan Shi, Hailong Lu

Abstract: Quantifying the presence of gas hydrates within sediments is essential for accurately assessing their resource potential and effectively exploiting gas hydrate-bearing sediments (GHBS). Common geophysical methods for determining gas hydrate saturation include well-logging, seismic reflection, and controlled-source electromagnetic (CSEM) surveys, which detect changes in the electrical and acoustic properties of sediments. However, different methods can yield varying saturation estimates even within the same area, and the applicability of these techniques has not been fully explored. This review examines the typical anomalies associated with gas hydrate presence in seismic, well-logging, and CSEM surveys, assessing the underlying principles, strengths, and limitations of each of these geophysical methods. Case studies and method comparisons illustrate the application of these techniques across various geological settings, emphasizing the complex interplay between hydrate satu ration, sediment properties, and measurement frequencies. Characterizing GHBS using geophysical methods remains challenging due to the oversimplification of rock physical models for natural gas hydrate systems, as well as the discrepancies between pore-scale distribution and larger scales of geophysical measurement tools. To address these issues, advanced rock physics models that integrate resistivity and elastic properties – while ac counting for the coexistence of gas hydrates and free gas, as well as anisotropic sediment behavior – are essential for improving the accuracy of saturation estimates. Additionally, resolving scale-related discrepancies through advanced upscaling techniques and integrated multi-disciplinary datasets is critical for reliably extrapolating localized hydrate saturations to reservoir-scale resource evaluations.

Keywords: Gas hydrate, Saturation, Rock physics, Velocity, Geophysical exploration

Fig.16 Advanced rock physics models for GHBS: effects of seismic and electrical anisotropy caused by fracture-filling fine-grained sediments, diverse hydrate morphologies, and the coexistence of gas hydrate and free gas on resistivity, velocity, and attenuation. Influence of various well-logging measurements on porosity in GHBS.

Integrated analysis of the gas hydrate petroleum system in the western South Korea Plateau (WSKP), East Sea (Sea of Japan)

东海（日本海）韩国海台西部天然气水合物-石油系统综合分析

发表时间：2025年5月9日

发表期刊：《Marine and Petroleum Geology》

Kyoung-Jin Kim , Bo-Yeon Yi , Dong-Geun Yoo

    Abstract: This study provides the first comprehensive definition of the late Neogene to Quaternary deepwater fan system and gas hydrate (GH) petroleum system in the western South Korea Plateau (WSKP). An integrated geological and geophysical approach was employed to evaluate reservoir, source, and preservation potentials, establishing the WSKP as a promising target for GH exploration. The late Neogene to Quaternary deepwater fan system comprises submarine canyons, slope channel systems, and lobe complexes, with Lobe 1 and Lobe 2 identified as high-potential reservoirs. These lobe deposits demonstrated favorable reservoir properties, including maximum thicknesses of 15–38 m and 11–28 m, respectively, high lateral continuity, and elevated net-to-gross ratios. Source potential was attributed to two tectonostratigraphic units (MS2 and MS3), which exhibited high total organic carbon (>1.0 wt %) and hydrogen index values (>200 mgHC/gTOC) for bioigenic gas generation. Organic-rich claystones deposited under hemipelagic conditions served as effective source rocks. The biogenic gas window (20–60 ◦C) was observed at depths of 250–750 ms below the seafloor, corresponding to MS2 and MS3 intervals. Fault systems facilitated efficient gas migration, enabling upward transport from source rocks in MS2 and MS3 to reservoirs in MS4. Preservation potential was corroborated by seismic indicators such as bottom simulating reflectors, seismic attribute anomalies, and amplitude versus offset responses. This study offers a framework for understanding the GH petroleum system in the WSKP, advancing knowledge on depositional systems and GH accumulation. The findings contribute to understanding GH systems in back-arc basins and provide a foundation for future exploration.

Keywords: Gas hydrate petroleum system, Geological and geophysical exploration, Deepwater lobe deposits, Late Neogene to quaternary fan system, Western South Korea plateau, East sea

Fig. 10. Distribution map of seismic indicators for gas hydrate and free gas accumulations, overlaid on (A) time-structure map of the seafloor, (B) isochron map of MS4, (C) time-structure map of MB4, and (D) isochron map of MS3. Seismic indicators identified in the WSKP include BSRs, ERs, SCMs, and SCDs. BH, basement high; BL, basement low; BSR, bottom simulating reflector; ER, enhanced reflector; MB, megasequence boundary; MS, megasequence; SCD, seismic chimney with depression; SCM, seismic chimney with mound.

Recovery of methane from low-concentration coalbed methanevia hydrate formation enhanced by−SO3 −coated nanopolymers

通过三氧化硫涂层纳米聚合物增强从低浓度煤层甲烷水合物形成中回收甲烷

发表时间：2025年5月14日

发表期刊：《Langmuir 》

Zaizheng Jiang, Zhiliang Tu, Zhihe Xin, Guodong Zhang, Fei Wang, and Yongtao Zhang

Abstract: Low-concentration coalbed methane (LCCBM) is an abundant unconventional natural gas resource, but the utilization efficiency of methane (CH4) is very low. Sodium dodecyl sulfate (SDS) enhances hydration for CH4 recovery but generates foams during hydrate dissociation, limiting continuous production. To address this issue, the –SO3– group was fixed on the polystyrene nanopolymers (named –SO3–@PSNS) for enhancing hydration to recover CH4 from 21.59 mol% CH4/78.41 mol% N2 in this work. The optimal CH4 recovery effect was obtained when SDS concentration was 4 mmol/L and –SO3–@PSNS concentration was 8 mmol/L. Due to the foams generated by the addition of SDS during the hydrate decomposition, THF in the system decreased from 1 mol% to 0.37 mol% after the reaction but only decreased to 0.96 mol% when –SO3–@PSNS was added. –SO3–@PSNS has important prospects for the application of hydrate-based CH4 recovery from LCCBM.

Fig9. (a) Schematic of the formation of−SO3−@PSNS and (b) mechanism of−SO3 −@PSNS promoting methane hydrate formation.

Functionalized superparamagnetic iron oxide nanoparticles as a sustainable approach for gas hydrate control

功能化超顺磁性氧化铁纳米粒子作为一种可持续天然气水合物控制方法

发表时间：2025年5月22日

发表期刊：《ACS Omega》

Ali H. Karaly, Malcolm A. Kelland, and Mohamed F. Mady

Abstract: Gas hydrate blockage in multiphase flow lines is a critical issue in upstream operations. One method to prevent this from happening is by the use of kinetic hydrate inhibitors (KHIs). KHIs are polymers containing tailored amphiphilic groups. These polymers often have limited marine biodegradability, and their recovery and recycling to reduce operational costs remain a challenge. A novel approach involves attaching KHIs to magnetic nanoparticles, enabling recovery and recycling without environmental discharge. We have developed superparamagnetic iron oxide nanoparticles (SPIONs) reacted first with vinyltrimethoxysilane (VTMS) and then coated withN-vinylpyrrolidone/N-vinyl caprolactam (VP/VCap) copolymer chains using radical polymerization of the VP and VCap monomers (SPIONs-VTMS-VPVCap). These nanoparticles are stable in aqueous solutions with a particle size of 10 nm and a dispersion size of 205 nm. High-pressure tests demonstrated that SPIONs-VTMS-VPVCap performed comparably to the free VP/VCap copolymer, achieving a hydrate formation onset temperature (To) of 12.9 °C at 5000 ppm. Significantly, the magnetic KHIs were successfully recovered and reused multiple times without performance loss. The solution exhibited a high cloud point (80 °C) and compatibility with n-butyl glycol ether (BGE), enhancing the performance. Adding 5000 ppm of BGE lowered the hydrate formation To to 7.3 °C, a 9.7 °C improvement compared to no additive. These results establish a proof of concept for recyclable magnetic KHIs, offering a sustainable solution to eliminate chemical discharge in marine environments while maintaining effective hydrate inhibition.

Fig5. TEM image of (a) SPIONs at 50 nm scale, (b) SPIONs-VTMS at 100 nm scale, (c) SPIONs-VTMS-VPVCap at 50 nm scale, and (d) SPIONsVTMS-VPVCap at 10 nm scale.

Methane clumped isotopes of shallow gas hydrates in the Haima cold seeps, South China Sea: Implications for marine carbon cycling and sequestration

中国南海海马冷泉浅层天然气水合物的甲烷团块同位素： 对海洋碳循环和固碳的影响

发表时间：2025年5月8日

发表期刊：《Marine and Petroleum Geology》

Haodong Chen, Jing Zhao , Qianyong Liang, Jiacheng Li, Junxi Feng, Xi Xiao, Zongheng Chen, Yun Li , Yongqiang Xiong

Abstract: Determining the methane sources and sinks of natural gas hydrates is pivotal to understanding carbon cycling over geological history. However, methane sources in natural gas hydrates remains poorly understood. In this study, we collected samples of hydrate-bound gas and pore fluid from shallow sediments in the Haima cold seeps of the Qiongdongnan Basin, South China Sea, and conducted various geochemical analyses to identify the sources and sinks of methane in this area. Particularly, methane clumped isotopes, an emerging method for tracing methane sources and sinks, were applied. Our results indicate that thermogenic methane accounts for 47.3 % of the shallow gas hydrates in the seeps, microbial methane being the rest. Furthermore, the data of headspace gas and pore water indicate the trace of anaerobic oxidation of methane (AOM) in the methane captured in shallow gas hydrates. By comparing our results with published datasets for deep gas hydrates, we refined the generation and accumulation span of biogenic methane as the Pliocene to Quaternary. Findings from this study highlight the contributions from different sources to hydrate-bound gas in the Qiongdongnan Basin and the coupled rela tionship between shallow gas hydrate formation, and deep oil and gas reservoirs. Our work advances the un derstanding of methane gas depletion and carbon sequestration in shallow sediments associated with cold seeps, and enhances the knowledge basis for the future exploitation of natural gas hydrates.  

Keywords: The Haima cold seeps, AOM, Methane clumped isotope, Carbon sequestration, Gas hydrate

Fig. 4. (a) A two-endmember mixing model, where right line is the mixing curve and the black is the equilibrium curve. The red dots are the percentages of thermogenic gases. Blue diamonds are samples of this study. The yellow dashed lines are the AOM model simulated within the error margins and yellow arrows indicate trends of AOM. (b) Profiles of sediment methane carbon isotopic ratio (δ13CCH4, blue) and methane (pink) and sulfate (green) concentrations. The yellow area indicates AOM process in the sediments. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)