基于树状分叉网络的增强型地热系统采热计算分析

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英文篇名：Calculation and analysis of extracting heat in the enhanced geothermal system based on tree-like branching network 作者：张林 ; 姚军 ; 樊冬艳 英文作者：Zhang Lin;Yao Jun;Fan Dongyan;College of Petroleum Engineering,China University of Petroleum; 关键词：增强型地热系统 ; 树状分叉网络 ; 离散裂缝网络模型 ; 热流耦合 ; 解析解 英文关键词：enhanced geothermal system(EGS);;tree-like branching network;;discrete fracture network model(DFN);;thermal-hydraulic coupled;;analytical solution 中文刊名：NCNY 英文刊名：Renewable Energy Resources 机构：中国石油大学(华东)石油工程学院; 出版日期：2019-02-20 出版单位：可再生能源 年：2019 期：v.37;No.246 基金：国家自然科学基金(51504277,51504276,61573018,41502131);; 中央高校基本科研业务费专项资金资助项目(16CX05018A,17CX02008A) 语种：中文; 页：NCNY201902020 页数：8 CN：02 ISSN：21-1469/TK 分类号：127-134

摘要

文章以分形理论和离散裂缝网络模型为基础,利用树状分叉网络表征离散缝网,构建出EGS热流耦合解析模型。利用Laplace变换方法得到该模型中干热岩储层的温度解析解,并分析了分叉参数和生产参数对增强型地热系统累计采出热量的影响。分析结果表明:裂缝的分叉级数对出口端缝网温度影响较大;当裂缝的长度比从0.5逐渐增加至0.7时,缝网出口温度的热突破时间从1.8 a左右逐渐延长至3 a左右;与裂缝长度比为0.5的工况相比,当裂缝长度比为0.7时,20 a内增强型地热系统的累计采出热量增加了2×109kJ;裂缝的开度比对水的流速影响较大,当裂缝的开度比增大时,增强型地热开采系统累计采出热量的增长速度呈现出先快后慢的变化趋势;注水速度的增大会缩短热突破时间,注水温度对热突破时间影响不大。
        Based on fractal theory and discrete fracture network model,this paper uses tree-like branching network to characterize the discrete fracture network and constructs an EGS heat flow coupling analytical model.Based on this model,the temperature analytical solution of dry hot rock reservoir is obtained by Laplace transform method,and the influence of fractal branching parameters and production parameters on heat extraction of EGS is analyzed.The analysis results show that the levels of the branching fracture has a great influence on the temperature of the fracture network's outlet.When the length ratio of fractures increases from 0.5 to 0.7,the thermal breakthrough time is extended from 1.8 a to 3 a.Compared with the working condition that the length ratio of the fractures is 0.5,the heat extraction of EGS running for 20 years increases by 2×10~9kJ when it's 0.7.The aperture ratio of fractures has a greater influence than the flow rate of water.When the aperture ratio of fractures increases,the growth rate of the heat extraction of EGS shows a trend of rapid growth first and slowness.The increase of the injection velocity will shorten the thermal breakthrough time;and the temperature of the injection water has little effect on the thermal breakthrough time.

引文

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