热储分层影响EGS采热的数值模拟研究
收稿日期: 2014-05-23
修回日期: 2014-07-09
网络出版日期: 2014-08-30
基金资助
国家高技术发展863计划项目（2012AA052802）；中国科学院“百人计划”项目
Numerical Study of EGS Heat Extraction from Stratified Heat Reservoirs
Received date: 2014-05-23
Revised date: 2014-07-09
Online published: 2014-08-30
由于岩石构造不同、天然裂隙的差异以及压裂过程的随机性等因素，增强型地热系统（EGS）人工热储通常具有较强的非均质性。探究热储的非均质性对EGS热开采过程的影响，对EGS性能预测与分析评价有重要意义。论文考虑到热储沿深度方向的非均质性，基于等效分层多孔介质物理模型，并使用自主开发的EGS数值模型，模拟了多个具有分层热储EGS的长期运行过程，发现热储深度方向上非均质性对热能的开采影响显著，而流量分布的不均匀性是导致系统采热性能下降的主要原因。为了方便分析和评价，我们建立一种新的定量化描述热储非均质性的方法，然后基于更多的非均质热储EGS算例结果，拟合得到EGS采热性能与热储非均质性的定量关系式。
关键词： 增强型地热系统（EGS）; 数值模拟; 等效分层多孔介质; 非均质性
黄文博 , 陈继良 , 蒋方明 . 热储分层影响EGS采热的数值模拟研究[J]. 新能源进展, 2014 , 2(4) : 295 -304 . DOI: 10.3969/j.issn.2095-560X.2014.04.009
Strong heterogeneity exists in enhanced geothermal systems (EGS) artificial heat reservoir due to factors such as different rock formations, the pre-existence of natural fractures and the uncertainty of stimulation process. Exploring the influence of reservoir heterogeneity on EGS heat extraction is of great importance for predicting and comprehensively evaluating the performance of EGS. In this paper, we take the reservoir as an equivalent stratified porous medium and employ the previously self-developed numerical model to conduct a series of simulations of the long-term heat extraction process of EGSs with different reservoir porosity distributions. Results indicate that the heat extraction performance is significantly affected by the reservoir heterogeneity. To facilitate the analysis and evaluation, we derive a formula to quantitatively describe the heterogeneity of the reservoir based on a detailed analysis to the effects of the fluid seepage flow field on the heat extraction performance. Further, we obtain a quantitative relationship of EGS heat extraction performance versus reservoir heterogeneity by fitting the calculated results from 30 cases, in which the stratified reservoirs are randomly assigned with differing porosity distributions.
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