Impact of micro- and macro-scale consistent flows on well performance in fractured shale gas reservoirs
Impact of micro- and macro-scale consistent flows on well performance in fractured shale gas reservoirs
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DOI：
10.1016/j.jngse.2016.05.005
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发表时间：
2016-11-01
影响因子：
--
通讯作者：
Tang, Furong
中科院分区：
文献类型：
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作者：
Liu, Jia;Wang, J. G.;Tang, Furong
页岩气革命来自水平钻井和水力压裂技术的巧妙结合，可以创造一个用于天然气生产的裂缝性气藏。裂缝性页岩气藏的气井动态受裂缝网络和页岩基质中复杂气体流动状态的影响。裂缝网络中宏观流动与泥岩基质中微观流动的一致性决定了气井的产气曲线，是气井设计的关键问题。本文提出了一个数值模型，研究微观和宏观尺度一致的气体流动对裂缝性页岩气藏的井动态的影响。在该数值模型中，宏观尺度的气体流动遵循达西定律在裂缝网络和页岩基质中的微观流动是由扩散控制的气体传输模型来描述。然后得到两个表观扩散系数或模型。它们将粘性流动与滑移边界、分子扩散（即分子自扩散）、努森扩散和吸附层中的表面扩散结合起来。研究了这两种页岩基质内气体运移扩散模型的性能，并与Singh和Javadpour（2013）以及Darabi等人（2012）提出的两种表观渗透率模型进行了比较。此外，裂缝渗透率和压缩系数的压力相关各向异性被纳入到数值模型中。该数值模型通过巴内特页岩气井的解析解和历史匹配进行了验证。最后，对不同情况下的裂缝性气藏进行了数值模拟，并通过参数研究分析了产量曲线的形态。研究发现，如果能很好地设计微观和宏观流动的一致性，就能有效地设计页岩气井，提高天然气采收率，延长气井寿命。(C)© 2016 Elsevier B.V.版权所有。
Shale gas revolution comes from the skillful combination of horizontal drilling and hydraulic fracturing technology that can create a fractured gas reservoir for gas production. The well performance in the fractured shale gas reservoir is significantly impacted by the complicated gas flow regimes in both fracture network and shale matrix. The consistency between the macro-flow in fracture network and the micro-flow in shale matrix determines the gas production curve, thus being a key issue to gas well design. This paper proposes a numerical model to investigate the impact of micro- and macro-scale consistent gas flows on well performance in fractured shale gas reservoirs. In this numerical model, the macro-scale gas flow follows the Darcy law in the fracture network and the micro-flow in the shale matrix is described by a diffusion-controlled gas transport model. Two apparent diffusion coefficients or models are then obtained. They incorporate viscous flow with slip boundary, molecular diffusion (i.e. molecular self-diffusion), Knudsen diffusion, and surface diffusion in the adsorption layer. The performances of these two diffusion models for the gas transport within shale matrix are investigated and compared with two apparent permeability models proposed by Singh and Javadpour (2013) and Darabi et al. (2012). Furthermore, the pressure-dependent anisotropy of fracture permeability and compressibility is incorporated into the numerical model. This numerical model is verified by an analytical solution and history matching for a Barnett shale gas well. Finally, a fractured gas reservoir with different scenarios is numerically simulated and the shapes of production curves are analyzed through parametric study. It is found that the enhancement of gas recovery efficiency and the life of a shale gas well can be effectively designed if the consistency of micro- and macro-flows can be well designed. (C) 2016 Elsevier B.V. All rights reserved.