Cementing operations in wellbores, especially for long casings, are often challenging and prone to deficiencies when not properly planned and executed. While exploring for and exploiting of geothermal resources at temperatures above the critical point of water was attempted in different drilling projects in recent years, the well design, and especially the procedure to run and cement long production casings became a key challenge for drilling engineers. For the first time, a reverse cementing job for a 2.97 km long production casing in a high-temperature geothermal well could be monitored and analyzed using a combination of permanently installed distributed fiber optic and electronic sensors as well as conventional well logging equipment. Data from the permanently installed sensors were used to monitor and evaluate the cementation process as well as the onset of the cement hydration. Based on the data, the understanding of downhole fluid dynamics during cementation could be improved. Our analysis suggests that the cement was diluted during cement placement and partly lost into the formation. These findings can help to better prepare for future drilling ventures under similar downhole conditions.

中文翻译：

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监测高温地热环境中的反向水泥作业

井眼中的固井作业，特别是长套管的固井作业通常具有挑战性，如果没有适当计划和执行，则容易出现缺陷。近年来，在不同的钻探项目中尝试在高于水的临界点的温度下探索和开发地热资源时，油井的设计，尤其是对长生产套管进行固井和固井的程序，成为钻井工程师面临的主要挑战。首次可以使用永久安装的分布式光纤和电子传感器以及常规测井设备的组合来监视和分析高温地热井中2.97 km长的生产套管的反向固井作业。永久安装的传感器中的数据用于监测和评估胶结过程以及胶结水化的开始。基于这些数据，可以提高对固井过程中井下流体动力学的理解。我们的分析表明，水泥在浇筑过程中被稀释，部分损失进入地层。这些发现有助于在类似的井下条件下更好地为未来的钻探业务做准备。