Abstract The world energy strategy for a sustainable development promotes the use of renewable energies. Among them, middle-enthalpy geothermal energy may be used to supply heat to service industries and urban centres. However, the costs for the acquisition of high-resolution geophysical data are still high compared to the economical return of the energy eventually extracted. This study proposes a method applied to the Greater Geneva Basin, Western Switzerland–Eastern France, to calibrate the inversion of gravity data by using old 2D seismic reflection acquisitions and available well data. First, we extract sonic logs from wells for the main geological units composing the basin. Each linear velocity versus depth relationship is extracted for each well and is used to perform a time to depth conversion of available seismic data. The influence of the heterogeneous (and heterogeneously distributed) Quaternary deposits is then removed from time data. Next, we re-calibrate the obtained geological model by applying a facies blocking approach. This allows us to obtain an updated geological model that is then used to invert gravity data. Results indicate that density anomalies are heterogeneously distributed across the basin and point out regions where well-known fault systems occur. Such regions may be selected for further geophysical prospection for higher-resolution methods. Finally, we identify a marked negative density anomaly beneath the city of Geneva. This may be interpreted as either less-compacted geological units or a well-developed fault system running below one of the most important urban centres of Europe.

中文翻译：

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基于改进的旧地震剖面的时深转换校准的经济型重力勘探，用于地热资源勘探

摘要 可持续发展的世界能源战略促进了可再生能源的利用。其中，中焓地热能可用于服务业和城市中心供热。然而，与最终提取的能量的经济回报相比，获取高分辨率地球物理数据的成本仍然很高。这项研究提出了一种应用于瑞士西部-法国东部的大日内瓦盆地的方法，通过使用旧的二维地震反射采集和可用的井数据来校准重力数据的反演。首先，我们从构成盆地的主要地质单元的井中提取声波测井。为每口井提取每个线速度与深度的关系，并用于执行可用地震数据的时间到深度的转换。然后从时间数据中去除异质（和异质分布）第四纪沉积物的影响。接下来，我们通过应用相块方法重新校准获得的地质模型。这使我们能够获得更新的地质模型，然后用于反演重力数据。结果表明，密度异常分布在整个盆地中，并指出了众所周知的断层系统发生的区域。可以选择这些区域进行更高分辨率方法的进一步地球物理勘探。最后，我们在日内瓦市下方发现了一个明显的负密度异常。这可能被解释为不太紧凑的地质单元或在欧洲最重要的城市中心之一下方运行的发育良好的断层系统。