CAREER: Carbon storage in widespread low-saturation gas hydrate systems

天然气水合物是一种看起来像冰的矿物质，但含有高浓度的甲烷，也被称为天然气。当水深超过500米时，天然气水合物在海底和海底下的海洋沉积物中形成。在世界范围内，海洋甲烷水合物估计储存了地球上20%到50%的甲烷。S可移动碳。温度和压力的扰动导致天然气水合物分解成甲烷气体和水。由于甲烷水合物中含有大量的碳，这些矿物的亚稳态，以及甲烷是一种强温室气体的事实，许多科学家推测，从天然气水合物中释放出来的甲烷可能是地球许多地区的关键因素。美国的大型全球变暖事件。然而，锁在海洋沉积物中的天然气水合物的数量尚不清楚，目前的估计相差四个数量级。该研究使用了可公开获取的学术和工业地球物理信息的测井曲线，以及从海洋沉积物中钻取的岩心测井曲线，结合新的数学方法来评估、建模和估计不同海洋环境中甲烷天然气水合物的数量。然后，这些信息被用于提供有关全球海底天然甲烷水合物的发生、分布和数量的关键、首次信息。这项工作的更广泛影响包括石油和天然气行业在发现和评估经济上可行的天然气储量时可以使用的信息；研究与教育的整合，涉及大量学生，他们将参与项目的数据分析和解释部分；将补充之前在墨西哥湾的天然气水合物评估；并补充了由国家科学基金会支持的国际海洋发现计划资助的即将进行的研究巡航。这项研究将有助于支持在科学领域人口统计学代表性不足的研究者，将支持视频实地考察的发展，并为学生在学术界以外的地质学职业提供重要信息。天然气水合物的评估和估计是基于已经存在的全球海上石油工业地球物理测井数据，但尚未对天然气水合物进行系统分析。在勘探研究中，石油行业通常会在与天然气水合物稳定性相吻合的浅层段收集测井数据，但往往会忽略这一点，因为他们对深层的主要液态石油层感兴趣，而不是天然气水合物的产层。到目前为止，科学家们还没有开发这个巨大的数据宝库。本研究项目侧重于这些有价值但未充分利用的数据。研究将涉及研究者、她的研究生和她的钻孔地球物理学课程。他们将检查和分析北大西洋、北海、西澳大利亚近海和墨西哥湾的测井曲线，使用新颖的数学和概念工具，将石油工业测井曲线的岩石物理分析与数值模拟和地球化学测量相结合，以帮助约束和了解全球天然气水合物的分布和饱和度。得到的信息将用于为全球气候模式提供信息，并提供关于天然气水合物对全球气候变化影响的准确信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Natural gas hydrates are minerals that look like ice, but contain a highly concentrated amount of methane, also known as natural gas. Natural gas hydrates form on the seafloor and in marine sediments beneath the seafloor when water depths exceed ~500 m. Worldwide, marine methane gas hydrates are estimated to store 20% to 50% of Earth?s mobile carbon. Perturbations to temperature and pressure cause gas hydrates to dissociate into methane gas and water. Due to the large reservoir of carbon in methane gas hydrates, the metastability of these minerals, and the fact that methane is a strong greenhouse gas, many scientists have theorized that methane liberated from natural gas hydrates may be a key player in many of Earth?s large global warming events. However, the amount of gas hydrate locked in marine sediments is not well known, with present estimates varying by four orders of magnitude. This research uses well logs from publicly accessible academic and industry geophysical information and well logs from cores drilled into marine sediments in conjunction with new mathematical approaches to evaluate, model, and estimate the amount of methane gas hydrates in a broad spectrum of different marine settings. This information is then used to provide crucial, first-time information on the occurrence, distribution, amount of naturally occurring methane gas hydrates in the seafloor, worldwide. Broader impacts of the work include information that can be used by the petroleum and natural gas industry in discovering and assessing economically feasible natural gas occurrences; the integration of research and education involving large numbers of students who will be involved in the data analysis and interpretation parts of the project; will complement previous gas hydrate assessments in the Gulf of Mexico; and complements a pending research cruise funded by the National Science Foundation- supported International Ocean Discovery Program. The research will help support an investigator whose demographic is underrepresented in the sciences, will support the development of video field trips, and provide important information to students on careers in geology outside of academia. The assessments and estimates of natural methane gas hydrates are based on already existing data from petroleum industry geophysical well logs from offshore locations worldwide that already exists, but has not been systematically analyzed for natural gas hydrate. As a matter of course in exploration studies, the petroleum industry collects well log data in the shallow interval that coincides with gas hydrate stability, but often ignores it because their interest in in deeper seated major liquid petroleum plays, not gas hydrate occurrences. Up to now, scientists have not exploited this vast treasure trove of data. This research project focuses on these valuable, but underutilized data. Research will involve the investigator, her graduate students, and her Borehole Geophysics class. They will examine and analyze well logs from the north Atlantic, the North Sea, offshore Western Australia, and the Gulf of Mexico using novel mathematical and conceptual tools that combine the petrophysical analysis of petroleum industry well logs with numerical modeling and geochemistry measurements to help constrain and understand the distribution and saturation of natural gas hydrates worldwide. The resulting information will be used to inform global climate models and provide accurate information on the influence of gas hydrate on global climate change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.