Development of a combined geochemical-geophysical approach for quantification of regional submarine gas hydrate inventories

开发用于量化区域海底天然气水合物库存的地球化学-地球物理联合方法

• 批准号: 13758967
• 负责人: Dr. Christian Hensen
• 金额: --
• 依托单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/13758967?language=en
• 关键词: Development; combined; geochemical; geophysical; approach

The proposed project aims at developing a new approach to quantify the amount of gas hydrate (GH) in continental margin sediments by the complementary use of geochemical models and the implementation of the effective medium theory (EMT) for seismic modelling and inversion. Reflection seismics provides 2-D information on variations in P-wave interval velocities using migration velocity analysis (MVA), which will be inverted to determine in situ GH concentrations. In contrast, numerical models will provide reliable predictions of the formation potential of methane and GH when calibrated against geochemical data from ODP sites. Preliminary results show that the prediction of GH inventories by seismic methods is highly sensitive to the accurate determination of porosities. This may cause large uncertainties, which can be reduced by calibration against the numerical model. The basic strategy is to use the geochemical approach as constraint for basic parameterisations of the geophysical model in the vicinity of ODP sites. In turn, a well-calibrated geophysical model will then provide useful model inputs along seismic lines where no drilling data are available for geochemical modelling. This approach will yield solid information on regional variables (e.g. sediment thickness, heat flow, degradation constants), which can be used for empirical predictions of the GH inventory and distribution. In addition, selected key studies will be performed for high flux scenarios (e.g. mud volcanoes) to improve estimates of their proportional significance for the total GH inventory.

该项目旨在通过补充使用地球化学模型和实施有效介质理论（EMT）进行地震建模和反演，开发一种新方法来量化大陆边缘沉积物中天然气水合物（GH）的数量。反射地震学使用偏移速度分析 (MVA) 提供有关 P 波层速度变化的二维信息，该信息将被反演以确定原位 GH 浓度。相比之下，当根据 ODP 站点的地球化学数据进行校准时，数值模型将提供甲烷和 GH 形成潜力的可靠预测。初步结果表明，地震方法预测GH库存对孔隙度的准确测定高度敏感。这可能会导致很大的不确定性，可以通过针对数值模型进行校准来减少不确定性。基本策略是使用地球化学方法作为 ODP 站点附近地球物理模型基本参数化的约束。反过来，经过良好校准的地球物理模型将沿着地震线提供有用的模型输入，而在这些情况下，没有钻井数据可用于地球化学建模。这种方法将产生有关区域变量（例如沉积物厚度、热流、退化常数）的可靠信息，可用于 GH 库存和分布的经验预测。此外，还将针对高通量情景（例如泥火山）进行选定的关键研究，以改进对其对 GH 总库存的比例重要性的估计。