Ciotoli Giancarlo, Procesi Monia, Etiope Giuseppe, Fracassi Umberto, Ventura Guido
Consiglio Nazionale delle Ricerche, Istituto di Geologia Ambientale e Geoingegneria, Via Salaria km 29300, 00015, Monterotondo, Rome, Italy.
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143, Rome, Italy.
Nat Commun. 2020 May 8;11(1):2305. doi: 10.1038/s41467-020-16229-1.
Earth's hydrocarbon degassing through gas-oil seeps, mud volcanoes and diffuse microseepage is a major natural source of methane (CH) to the atmosphere. While carbon dioxide degassing is typically associated with extensional tectonics, volcanoes, and geothermal areas, CH seepage mostly occurs in petroleum-bearing sedimentary basins, but the role of tectonics in degassing is known only for some case studies at local scale. Here, we perform a global scale geospatial analysis to assess how the presence of hydrocarbon fields, basin geodynamics and the type of faults control CH seepage. Combining georeferenced data of global inventories of onshore seeps, faults, sedimentary basins, petroleum fields and heat flow, we find that hydrocarbon seeps prevail in petroleum fields within convergent basins with heat flow ≤ 98 mW m, and along any type of brittle tectonic structure, mostly in reverse fault settings. Areas potentially hosting additional seeps and microseepage are identified through a global seepage favourability model.
通过油气渗漏、泥火山和弥散性微渗漏，地球上的碳氢化合物脱气是大气中甲烷（CH）的主要天然来源。虽然二氧化碳脱气通常与伸展构造、火山和地热区有关，但CH渗漏大多发生在含油沉积盆地，不过构造作用在脱气过程中的作用仅在一些局部尺度的案例研究中有所了解。在这里，我们进行了一次全球尺度的地理空间分析，以评估油气田的存在、盆地地球动力学和断层类型如何控制CH渗漏。结合陆上渗漏、断层、沉积盆地、油田和热流的全球清单的地理参考数据，我们发现，在热流≤98 mW/m的汇聚盆地内的油田以及沿着任何类型的脆性构造结构（大多处于逆断层环境）中，碳氢化合物渗漏较为普遍。通过一个全球渗漏适宜性模型确定了可能存在额外渗漏和微渗漏的区域。
