中深层同轴套管井热提取模式下沿程温度分布特性研究  

Research on the characteristics of fluid temperature distribution along the pipe of medium-deep coaxial tube well with thermal extraction mode

作　　者：刘博洋 刘俊 张育平 陶鹏飞 周聪 LIU Boyang;LIU Jun;ZHANG Yuping;TAO Pengfei;ZHOU Cong(Shaanxi Zhongmei New Energy Company Ltd.,Shaanxi Union Research Center of University and Enterprise for Geothermal Resource Exploration and Low-carbon Utilization,Xi’an 710054,China;Shaanxi Coal Geology Group Company Ltd.,Key Laboratory of Coal Resources Exploration and Comprehensive Utilization,Ministry of Natural Resources,Xi’an 710021,China)

机构地区：[1]陕西中煤新能源有限公司陕西省“四主体一联合”地热资源勘查与低碳利用校企联合研究中心,陕西西安710054 [2]陕西省煤田地质集团有限公司自然资源部煤炭资源勘查与综合利用重点实验室,陕西西安710021

出　　处：《区域供热》2023年第4期55-63,共9页District Heating

基　　金：陕西省秦创原“科学家+工程师”队伍建设项目(2022KXY-039);陕西省科协青年人才托举计划项目(NYHB202218);陕西省国有资本经营预算科技创新专项资金项目(2022-10)。

摘　　要：根据中深层同轴套管井换热原理建立传热模型,开展热提取模式下的沿程温度分布特性研究。结果表明:在热提取过程中,内管中的流体温度沿着流动方向不断下降,且在供暖季前期的下降程度更大。在运行流速较低时,井底流体温度较高,流速在0.3 m·s^(-1)条件下的井底温度与0.7 m·s^(-1)时的温度相比提高了19.4℃,但由于内管流体温度的下降程度较大,导致出口温度优势不明显。套管井长度越大,内管流体温度的下降程度就越大,长度由1500 m增加至3000 m时,内管流体温度损失由1.5℃增加至10.7℃。因此,在流速较低或套管井长度较大时,内管做好保温措施有助于提升热提取能力。此外,由于热提取期间套管井周围的岩土体温度不断下降,以及受运行工况的影响,流体无法与较深处的高温岩土体实现充分换热,套管井的出口温度会低于较深处中深层岩土体未被干扰时的温度。在众多热提取因素中,套管井的沿程温度分布受入口水温、运行流速、套管井长度、岩土体导热系数和地温梯度的影响较大,其与入口温度基本呈线性相关,运行流速和套管井长度对深部位置的温度分布影响更明显,在岩土体导热系数和地温梯度较高的条件下,内管中流体温度的下降程度较大。According to the heat transfer principle of medium-deep coaxial tube well,the heat transfer model is proposed to demonstrate the characteristics of fluid temperature distribution along the pipe.The results show that fluid temperature in inner pipe gradually reduces in the flow direction and reduces more in initial heating period.In the condition of lower velocities,the fluid temperature at well bottom is higher.The bottom temperature at 0.3 m·s^(-1)is 19.4℃higher than that at 0.7 m·s^(-1)but the advantage of outlet temperature is not obvious due to a large temperature drop in inner pipe.The fluid temperature in inner pipe reduces more for the tube well with a longer length.The fluid temperature loss increases from 1.5℃to 10.7℃when the pipe length increases from 1500 m to 3000 m.Thus,in the condition of lower velocity and/or longer pipe length,the thermal extraction capacity of tube well could be obviously enhanced by insulating the inner pipe.Additionally,the outlet temperature of tube well is lower than the undisturbed temperature of medium-deep rock-soi.l On the one hand,the rock-soil temperature surrounding the tube well gradually declines.On the other hand,the fluid in tube well cannot fully exchange the heat with deeper rock-soi.l Among the investigated thermal extraction factors,inlet temperature,operating velocity,pipe length,rock-soil thermal conductivity and geothermal gradient impact the fluid temperature distribution more obviously.The temperature distribution follows inlet fluid temperature linearly.Operating velocity and pipe length have a larger impact on the temperature distribution in deeper depth.In the condition of higher rock-soil thermal conductivity and geothermal gradient,a larger temperature drop exists in inner pipe fluid temperature.

关 键 词：中深层 套管井 传热 流体温度 

分 类 号：TU832[建筑科学—供热、供燃气、通风及空调工程] P314[天文地球—固体地球物理学]