基于微觀機理的頁巖氣運移分析

張鵬偉; 胡黎明; 溫慶博

doi:10.13374/j.issn2095-9389.2018.02.002

基于微觀機理的頁巖氣運移分析

doi: 10.13374/j.issn2095-9389.2018.02.002

張鵬偉^1,2,
胡黎明^1,2, ,,
溫慶博^1,2

1) 清華大學水利水電工程系, 北京 100084
2) 清華大學水沙科學與水利水電工程國家重點實驗室, 北京 100084

基金項目:

清華大學自主科研計劃資助項目（THZ20161080101）；國家自然科學基金資助項目（41372352）

詳細信息

中圖分類號: TU42
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出版歷程
- 收稿日期: 2017-05-06

Micro-mechanism analysis of shale gas migration

ZHANG Peng-wei^1,2,
HU Li-ming^{1,2
, ,},
WEN Qing-bo^1,2

1) Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
2) State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China

摘要

摘要: 認識氣體在頁巖孔隙中的運移機理對頁巖氣開采具有重要的科學意義.頁巖作為一種致密巖石，孔隙尺寸分布主要集中在幾納米到百納米之間，小孔隙尺寸與氣體的平均分子自由程在同一個數量級，氣體與孔隙邊壁的碰撞對流動起到控制作用.本文針對頁巖氣開采過程中孔隙中氣體流動過程，建立了考慮氣體滑移、Knudsen擴散、Langmuir等溫吸附、孔隙壓縮等過程的多場耦合控制方程.分析了流態變化對滑移效應的影響，得到了考慮滑移效應的臨界孔徑，并針對實際中不同頁巖儲層有機質含量的差異，分析了解吸機制對頁巖氣產氣率、產氣量的貢獻.研究還表明孔隙壓縮性對產氣率影響顯著，通過考慮開采過程中孔隙壓縮，可以更真實地反映頁巖氣運移過程.
- 滑移流動 /
- 孔隙壓縮 /
- Knudsen擴散 /
- Langmuir等溫吸附 /
- 頁巖氣
Abstract: For shale gas exploitation, it is scientifically essential to clarify the mechanism of gas flow in nanopore media. Shale is a kind of tight rock, whose pore size mainly ranges from several nanometers to dozens of nanometers. Since it is of the same magnitude as the gas molecular mean free path, the collision between the gas molecular and pore surface is not negligible for gas flow and results in the failure of Darcy's law when describing this low permeability reservoir gas flow mechanism. In order to clarify the micropore gas flow mechanism and the real extraction process of shale gas, a multiphysics governing equation was established, which combines slip flow, Knudsen diffusion, Langmuir isotherm adsorption, and pore compressibility. The effect of different flow regimes on slip flow was analyzed, and the threshold pore size was obtained with consideration of the slippage effect. Then, the contribution of desorption to gas production rate and gas output was clarified based on the organic content of disparate shale samples. The results indicate that the gas production rate is sensitive to pore compressibility, and it is more reasonable to simulate the gas flow process when considering pore compressibility.
- slip flow /
- pore compressibility /
- Knudsen diffusion /
- Langmuir isotherm adsorption /
- shale gas

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