کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5782170 | 1637146 | 2017 | 16 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Free gas accumulations in basal shear zones of mass-transport deposits (Pearl River Mouth Basin, South China Sea): An important geohazard on continental slope basins
ترجمه فارسی عنوان
تجمع گازهای آزاد در مناطق برشی اولیه توده حمل و نقل سپرده (حوضه دهان دریای رودخانه مروارید، دریای جنوبی چین): یک جوی خطرناک در حوضه شیب قاره
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
زمین شناسی اقتصادی
چکیده انگلیسی
Free gas is an important trigger of instability on continental slopes, and resulting mass-wasting strata can potentially form competent seals to hydrocarbon accumulations. This work uses two high-quality 3D seismic volumes to investigate fluid accumulations at the base of mass-transport deposits in the Pearl River Mouth Basin, South China Sea. In parallel, IODP/ODP borehole data are used to document the petrophysical character of mass-transport deposits formed in similar continental-slope environments to the South China Sea. The interpreted data show gas accumulations as comprising enhanced seismic reflections that are discordant, or vertically stacked, below mass-transport deposits with chaotic seismic facies. Gas was accumulated in basal shear zones of mass-transport deposits in response to differences in capillary pressure and porosity. Free gas in Zone A covers an area of at least 18Â km2. In Zone B, the free gas is sub-circular in plan view and covers an area of 30.58Â km2 for a volume of sediment approaching 1.5Â km3. This work is important as it shows that vertical migration of gas is not significant in mass-transport deposits from the Pearl River Mouth Basin, but up-dip migration along their basal shear zones is suggested in multiple locations. As a result, free gas can pinch-out laterally to extend 1-2Â km beyond these same basal shear zones. As a corollary, we show that free gas accumulations below mass-transport deposits comprise an important geohazard and should be taken into account when drilling continental-slope successions in both the South China Sea and continental margins recording important mass wasting. Strata charged with free gas form weak layers, hinting at a novel trigger of retrogressive slope failures on continental slopes worldwide.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine and Petroleum Geology - Volume 81, March 2017, Pages 17-32
Journal: Marine and Petroleum Geology - Volume 81, March 2017, Pages 17-32
نویسندگان
Qiliang Sun, Tiago Alves, Xinong Xie, Jiaxiong He, Wei Li, Xianglong Ni,