煤田地质与勘探2024，Vol.52Issue(1)：117-128,12.DOI:10.12363/issn.1001-1986.23.12.0827
裂缝分布对CO2-EGS热提取的影响研究
Effects of fracture distribution on heat extraction through CO2-EGS
摘要
Abstract
Geothermal energy,a promising source of renewable energy,has attracted considerable attention.In deep geo-thermal reservoirs,complex fracture networks formed by artificial stimulation provide predominant channels for heat ex-traction.Therefore,the spatial distribution of fractures directly affects the heat extraction efficiency.This study aims to explore the effects of different spatial distributions of fractures on the heat recovery performance.Based on the fracture network following a power-law distribution,this study systematically investigated the effects of the fracture network with different values of fracture length index(a)and density(β)on the heat recovery performance of a new enhanced geothermal system with CO2 as injection fluid(CO2-EGS)using the THM coupling model established under the TOUGH2MP-FLAC3D framework.Furthermore,this study presented a detailed evaluation of the thermal performance of CO2-EGS using five evaluation indicators:heat breakthrough time,CO2-EGS life,heat production rate,total heat produc-tion,and heat production efficiency,obtaining the following results.Under a constant injection rate,an increase in a cor-responded to a smaller proportion of long fractures,a smaller number of penetrating fractures between the injection and production wells,a larger fracture width,and higher decreasing rates of the production temperature and heat production rate.These led to earlier heat breakthroughs,thereby shortening the CO2-EGS life and reducing the total heat production.In the case of a constant a,a greater fracture density β was associated with a greater number of fractures and lower de-creasing rates of the production temperature and heat production rate.These prolonged the thermal breakthrough time and CO2-EGS life and improved heat production.Specifically,the heat breakthrough time,EGS life,and total heat pro-duction could increase by up to 15.65 a,about 10 years,and about 22.77% ,respectively.In contrast,increasing a de-creased the thermal breakout time and total heat production by 13.1 a and 20.8% ,respectively.Therefore,increasing the proportion of long fractures and fracture density is instrumental in improving fracture connectivity,promoting convect-ive heat transfer of fluids,improving the effects of fractures in heat recovery,and enhancing heat production.The results of this study can serve as a theoretical guide for the hydraulic fracturing of hot dry rocks to generate fractures and en-hance their permeability.关键词
增强型地热系统/裂缝分布/热性能/评价指标/数值模拟Key words
enhanced geothermal system(EGS)/fracture distribution/thermal performance/evaluation indicator/numer-ical simulation分类
天文与地球科学引用本文复制引用
周庆,廖建兴,徐斌,姚亮,周浩宇,赵权..裂缝分布对CO2-EGS热提取的影响研究[J].煤田地质与勘探,2024,52(1):117-128,12.基金项目
贵州省科技计划项目(黔科合基础-ZK[2023]一般074) （黔科合基础-ZK[2023]一般074）
