Importance of rock properties on the producibility of gas shales
Importance of rock properties on the producibility of gas shales
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DOI：
10.1016/j.coal.2012.04.012
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发表时间：
2012-12-01
影响因子：
5.6
通讯作者：
Bustin, R. Marc
中科院分区：
文献类型：
--
作者：
Bustin, Amanda M. M.;Bustin, R. Marc
随着非常规天然气资源的开发，页岩油气藏的非均质性和复杂性日益显现。页岩的生产历史。在一系列互层地层内和来自相邻威尔斯的流体通常表现出无法解释的变化，并且来自数值模拟的预测很少准确。由于储集层和页岩岩石参数的可变性，页岩性质与储集层生产率之间的复杂相互作用很少明显。最难量化的参数之一是组构。本研究使用商业数值模拟器和现场及实验室确定的岩石性质，比较了页岩组构参数对其产量的相对重要性。组构参数包括应力依赖性裂缝渗透率，其控制通过裂缝网络的气体输送，以及有效裂缝间距，其控制通过基质的气体输送的路径长度，以及应力依赖性基质渗透率，其控制通过基质的气体输送。数值模拟的结果表明，对于大范围的应力依赖性裂缝渗透率、应力依赖性基质渗透率和裂缝间距，气页岩储层的产能受到通过基质的低效气体输送的限制。基质渗透率不是一个具体的数值，而是随着有效裂缝间距和裂缝渗透率而变化，低于基质渗透率时，天然气生产是不经济的。基质渗透率和有效裂缝间距对裂缝渗透率较大的地层的产能影响较大。裂缝有效间距对产量的影响大于基质渗透率的影响。与大裂缝间距（或小基质渗透率）相关的较低产量可以被大基质渗透率（或小裂缝间距）抵消。生产模拟还显示了对岩石地质力学性质的强烈依赖性，这影响了气体如何通过基质和裂缝随应力变化。地质力学性质对产量的影响取决于产量是否受到通过基质的气体输运的限制。当组构参数导致与基质无关的产量（小裂缝间距、大基质渗透率、小裂缝渗透率）时，产量仅由应力相关裂缝渗透率控制，其中较大的初始裂缝渗透率、较大的杨氏模量和较大的泊松比导致较高的产量。在这种情况下，杨氏模量比泊松比的影响力大得多。当组构参数导致基质限制产量时，反映基质渗透率随有效应力呈指数下降的岩石力学参数a对产量的影响最大。泊松比对生产率的影响不仅与织物参数有关，而且与杨氏模量和弹性模量有关。当生产是基质限制时，对于所有情况，较小的泊松比导致较高的生产，除了当α和杨氏模量都小时。(C)2012爱思唯尔有限公司版权所有。
As the development of unconventional gas resources has progressed, the heterogeneity and complexity of shales as gas and oil reservoirs have become apparent. The production histories from shales. both within a sequence of interbedded strata and from adjacent wells, commonly exhibit inexplicable variations and predictions from numerical modeling are rarely accurate. As a result of the variability in the reservoir and rock parameters of gas shales, the complex interaction between the shale properties and the producibility of the reservoir is seldom apparent One of the most difficult parameters to quantify is the fabric. This study compares the relative importance of the fabric parameters of gas shales on their producibility using a commercial numerical simulator and field and laboratory determined rock properties. The fabric parameters include the stress-dependent fracture permeability, which controls the gas transport through the fracture network, as well as the effective fracture spacing, which controls the path length for gas transport through the matrix, and the stress-dependent matrix permeability, which controls the gas transport through the matrix. The results of the numerical simulations show that for a wide range of stress-dependent fracture permeabilities, stress-dependent matrix permeabilities, and fracture spacings, the productivity of a gas shale reservoir is limited by inefficient gas transport through the matrix. The matrix permeability below which gas production is subeconomic is not a specific value, but varies with the effective fracture spacing and with fracture permeability. The matrix permeability and effective fracture spacing have a greater impact on the producibility of strata with larger fracture permeabilities. The influence of the effective fracture spacing on production is greater than the influence of the matrix permeability. The lower production associated with a large fracture spacing (or a small matrix permeability) can be offset by a large matrix permeability (or a small fracture spacing).The production simulations also show the strong dependence on the geomechanical properties of the rock, which affect how the gas transport through the matrix and fractures changes with stress. The influence of the geomechanical properties on the producibility depends on whether the production is limited by the gas transport through the matrix. When the fabric parameters result in a matrix-independent production (small fracture spacing, large matrix permeability, small fracture permeability), the production is solely controlled by the stress-dependent fracture permeability, with larger initial fracture permeability, larger Young's modulus, and larger Poisson's ratio resulting in higher production. In this case, Young's modulus is much more influential than the Poisson's ratio. When the fabric parameters result in a matrix-limited production, the rock mechanics parameter a, which relates the exponential decline of matrix permeability with effective stress, has the strongest influence on the producibility. The influence of Poisson's ratio on producibility not only varies with the fabric parameters, but also with the Young's modulus and a. When the production is matrix-limited, a smaller Poisson's ratio results in a higher production for all cases except when both a and Young's modulus are small. (C) 2012 Elsevier B.V. All rights reserved.