Multifracture response to supercritical CO2‐EGS and water‐ EGS based on thermo‐hydro‐mechanical coupling method
Multifracture response to supercritical CO2‐EGS and water‐ EGS based on thermo‐hydro‐mechanical coupling method
复制标题
基于热-水-机械耦合方法的超临界CO2-EGS和水-EGS多裂缝响应
DOI：
10.1002/er.4743
复制
发表时间：
2019
影响因子：
4.6
通讯作者：
辛莹
中科院分区：
文献类型：
--
作者：
Kelvin Bongole;孙致学;姚军;Asif Mehmood;王月英;Asif Mehmood;辛莹
水力压裂处理已成为开发深层干热岩（HDR）的重要技术。深部岩层往往包含微观和宏观尺度的天然裂缝（NF）。在存在NF的情况下，水力压裂过程可以形成由水力裂缝与NF之间的相互作用引起的复杂裂缝网络。在这项研究中，基于热-水-力学（THM）耦合方法，采用各种岩石本构模型，对复杂裂隙网络中的二氧化碳（CO2）基增强型地热系统（EGS）和水基EGS进行了分析。裂缝几何形状的复杂性影响热储的流体流动路径和传热效率。与CO2基EGS相比，水基EGS具有更早的热突破，生产温度迅速下降。二氧化碳可以很容易地获得热量，使其温度升高，从而减少过早热突破的影响。CO2基EGS和水基EGS都受到原地应力的影响;应力比的增加提高了裂缝渗透率，但导致早期冷热突破。当相同的注入速率应用于水基EGS和CO2基EGS时，水基EGS显示出更高的注入压力恢复。水基EGS具有比CO2基EGS更大的储层变形面积，水基EGS的热弹性本构模型显示出比热多孔弹性岩石模型更大的变形面积比。此外，较高的岩石模量值加速了水基EGS的储层变形。本研究建立了一个新的讨论，调查CO2基EGS和水基EGS在复杂裂缝性油藏中的性能。这项研究的结果将有助于加深对使用CO2或水作为EGS工作流体时所涉及的机制的理解。
Hydraulic‐fracturing treatments have become an essential technology for the development of deep hot dry rocks (HDRs). The deep rock formation often contains natural fractures (NFs) at micro and macroscales. In the presence of the NF, the hydraulic‐fracturing process may form a complex fracture network caused by the interaction between hydraulic fractures and NF. In this study, analysis of carbon dioxide (CO2)‐based enhanced geothermal system (EGS) and water‐based EGS in complex fracture network was performed based on the thermo‐hydro‐mechanical (THM) coupling method, with various rock constitutive models. The complexity of the fracture geometry influences the fluid flow path and heat transfer efficiency of the thermal reservoir. Compared with CO2‐based EGS, water‐based EGS had an earlier thermal breakthrough with a rapid decline in production temperature. CO2can easily gain heat rising its temperature thus reducing the effect of a premature thermal breakthrough. Both CO2‐based EGS and water‐based EGS are affected by in‐situ stress; the increase in stress ratio improved the fracture permeability but resulted in an early cold thermal breakthrough. When the same injection rate is applied to water‐based EGS and CO2‐based EGS, water‐based EGS displayed higher injection pressure buildup. Water‐based EGS had higher reservoir deformation area than CO2‐based EGS, and thermoelastic constitutive model for water‐based EGS showed larger deformed area ratio than thermo‐poroelastic rock model. Furthermore, higher values of rock modulus accelerated the reservoir deformation for water‐based EGS. This study established a novel discussion investigating the performance of CO2‐based EGS and water‐based EGS in a complex fractured reservoir. The findings from this study will help in deepening the understanding of the mechanisms involved when using CO2or water as a working fluid in EGS.