摘要
地热流体经供暖利用后尾水温度降低,经过滤、排气处理后的尾水中仍含有不同粒径的悬浮物、气体,因此回灌不可避免的会对储层造成负面影响,如堵塞储层导致回灌量衰减、热储温度降低甚至产生热突破等,这严重阻碍了地热回灌的长期可持续运行。评价回灌对储层的影响,对下一步全面推进、科学回灌及合理可持续开发利用、保护地热资源具有重要意义。本文以近几年鲁西北坳陷区开展的馆陶组热储回灌试验为基础,设立了一套评价指标,即用回灌前、后水质的变化率评价回灌对热储流体的影响,温度的变化率评价回灌对热储温度的影响,单位涌水量变化率、渗透系数的比值和单位回灌量比值评价回灌堵塞程度并确定了分级标准。评价结果表明,回灌不会改变储层流体的化学类型;回灌堵塞主要发生在回灌井周围,相比回灌前,回灌后回灌井的单位涌水量降低14.3%~59.0%、渗透系数为原来的41%~86%,末期单位回灌量为初期回灌量的51%~92%,回灌堵塞程度为轻度到严重。采灌井距180~500m,历经一个供暖季回灌对热储温度的影响较小,但回灌导致回灌井周边热储温度明显降低,历经一个非回灌期224d,从35.7℃恢复到40.53℃,恢复速率为0.036~0.022℃/d,还需658d才能恢复到原热储温度(55℃)。本区热储水位仍呈下降趋势,但回灌可延缓热储水位的下降速度。
The temporature of the geothermal tail water cools down after heat exchange.Tail water,even after treatment of filtering and degas treatment,still contains some suspending particles and gases.Hence reinjection would inevitably cause some negative impacts on the geothermal reservoir,such as reservior blockage induced decrease of reinjection rate,reservoir temperature drawdown lead to inmature thermal breakthrough.This will largely affect the sustainability of reinjection practices at sandstone geothermal reservoir.Evaluating the influence of reinjection in sandstone geothermal reservoir is of great significance to promote large-scale reinjection practices,sustainable development and protection of geothermal resource.Based on the geothermal tailwater reinjection test of the Guantao Formation geothemal reservoir,the paper established a set of evaluation indexes,in which the change rate of geothermal water chemical contents before and after the reinjection was used to evaluate the influence of reinjection to the geothermal fluid,and the temperature change rate to evaluate the influence of reinjection to the geothermal reservoir temperature,and the change rate of specific yield,permeability change ratio,and ratio of unit recharge to evaluate the severity degree of reinjection blockage,and finally set up the influence classification standard.The evaluation results show that the reinjection did not change the chemical composition of geothermal fluid.The blockage mainly occurred around reinjection wells.The specific yield fell down by 14.3%~59.0%after reinjection,and the permeability is about 41%~86% of its initial value,and the reinjection rate at later stage is about 51%~92% of that at the early stage,suggesting that the reinjection blockage severity is classified into medium to severe.The distance between the pumping and reinjections wells ranges from 180 to 500 mand it has less influence on the thermal reserves temperature after the rejection of one heating season.The reinjection has caused an obvious temperature dra
作者
冯守涛
王成明
杨亚宾
宋伟华
刘帅
赵季初
FENG Shoutao;WANG Chengming;YANG Yabin;SONG Weihua;LIU Shuai;ZHAO Jichu(The Second Institute of Hydrogeology and Engineering Geology,Shaondong Provincial Bureau of Geology&Mineral Resources(Shandong Provincial Lubei Geo-engineering Exploration Instituts),Shandong,Dezhou,253072;Shandong Provincial Research Center of Geothermal Resources and Reinjection,Shandong,Dezhou,253072)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2019年第S01期158-167,共10页
Acta Geologica Sinica
基金
山东省地质科研项目(编号鲁地字[2019]34号文)资助的成果.
关键词
砂岩热储
回灌
影响评价
鲁西北坳陷地热区
sandstone geothermal reservoir
reinjection
impact assessment
Northwest Shandong depression
