Chelating agents for diluted geothermal brine reinjection

IF 2.9 2区地球科学 Q3 ENERGY & FUELS

Geothermal Energy Pub Date : 2022-09-26 DOI:10.1186/s40517-022-00227-1

Jacquelin E. Cobos, Erik G. Søgaard

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Abstract

“Blue energy” could be produced by exploiting the large salinity gradient between geothermal fluids and freshwater through a SaltPower system. This study is an attempt to select the most favorable chemicals to avoid injectivity issues when a diluted geothermal fluid resulting from the SaltPower system is returned to the reservoir. Three synthetic chelating agents (oxalic acid, EDTA, and EDDS) and one natural (humic acid) were evaluated through speciation simulations and isothermal titration calorimetry (ITC) experiments. The speciation simulation results indicate that the degree of complexing is highly dependent on pH and chelating agent type. The ITC experiments show that the total heat for the formation of soluble metal–ligand complexes in the rock + geothermal brine system follows: EDTA > EDDS > oxalic acid > humic acid. The simulations and calorimetry results suggest that EDTA could be used to avoid the precipitation of Fe(III) oxides and other minerals (e.g., calcite and dolomite) inside the porous media upon the reinjection of diluted geothermal brine coming from SaltPower electricity production.

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稀释地热盐水回注用螯合剂

“蓝色能源”可以通过SaltPower系统利用地热流体和淡水之间的巨大盐度梯度来生产。这项研究旨在选择最有利的化学物质，以避免盐动力系统产生的稀释地热流体返回储层时的注入性问题。通过物种模拟和等温滴定量热(ITC)实验对三种合成螯合剂(草酸、EDTA和EDDS)和一种天然螯合剂(腐植酸)进行了评价。形态模拟结果表明，络合程度高度依赖于pH和螯合剂类型。ITC实验表明，岩石+地热卤水体系中形成可溶性金属配体配合物的总热量为:EDTA >edd祝辞草酸>胡敏酸。模拟和量热结果表明，EDTA可以避免在盐动力发电的稀释地热盐水回注时，多孔介质中Fe(III)氧化物和其他矿物(如方解石和白云石)的沉淀。

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来源期刊

Geothermal Energy Earth and Planetary Sciences-Geotechnical Engineering and Engineering Geology

CiteScore

5.90

自引率

7.10%

发文量

审稿时长

8 weeks

期刊介绍： Geothermal Energy is a peer-reviewed fully open access journal published under the SpringerOpen brand. It focuses on fundamental and applied research needed to deploy technologies for developing and integrating geothermal energy as one key element in the future energy portfolio. Contributions include geological, geophysical, and geochemical studies; exploration of geothermal fields; reservoir characterization and modeling; development of productivity-enhancing methods; and approaches to achieve robust and economic plant operation. Geothermal Energy serves to examine the interaction of individual system components while taking the whole process into account, from the development of the reservoir to the economic provision of geothermal energy.