The Upper Rhine Graben (URG) has been extensively studied for geothermal exploitation over the past decades. Yet, the thermal conductivity of the sedimentary cover is still poorly constrained, limiting our ability to provide robust heat flow density estimates. To improve our understanding of heat flow density in the URG, we present a new large thermal conductivity database for sedimentary rocks collected at outcrops in the area including measurements on (1) dry rocks at ambient temperature (dry); (2) dry rocks at high temperature (hot) and (3) water-saturated rocks at ambient temperature (wet). These measurements, covering the various lithologies composing the sedimentary sequence, are associated with equilibrium-temperature profiles measured in the Soultz-sous-Forêts wells and in the GRT-1 borehole (Rittershoffen) (all in France). Heat flow density values considering the various experimental thermal conductivity conditions were obtained for different depth intervals in the wells along with average values for the whole boreholes. The results agree with the previous heat flow density estimates based on dry rocks but more importantly highlight that accounting for the effect of temperature and water saturation of the formations is crucial to providing accurate heat flow density estimates in a sedimentary basin. For Soultz-sous-Forêts, we calculate average conductive heat flow density to be 127 mW/m2 when considering hot rocks and 184 mW/m2 for wet rocks. Heat flow density in the GRT-1 well is estimated at 109 and 164 mW/m2 for hot and wet rocks, respectively. Results from the Rittershoffen well suggest that heat flow density is nearly constant with depth, contrary to the observations for the Soultz-sous-Forêts site. Our results show a positive heat flow density anomaly in the Jurassic formations, which could be explained by a combined effect of a higher radiogenic heat production in the Jurassic sediments and thermal disturbance caused by the presence of the major faults close to the Soultz-sous-Forêts geothermal site. Although additional data are required to improve these estimates and our understanding of the thermal processes, we consider the heat flow densities estimated herein as the most reliable currently available for the URG.

中文翻译：

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使用沉积岩热导率的实验室测量值，对上莱茵河格拉本地区的热流密度进行估算

在过去的几十年中，对上莱茵河格拉本（URG）进行了广泛的地热开发研究。但是，沉积物覆盖层的热导率仍然受到限制，限制了我们提供可靠的热流密度估算值的能力。为了提高我们对URG中热流密度的理解，我们提供了一个新的大型导热系数数据库，用于收集该地区露头收集的沉积岩，包括（1）在室温（干燥）下的干燥岩石的测量；（2）高温下的干燥岩石（高温）和（3）室温下的水饱和岩石（潮湿）。这些测量结果涵盖了组成沉积序列的各种岩性，并与Soultz-sous-Forêts井和GRT-1钻孔（Rittershoffen）（全部在法国）中测得的平衡温度曲线有关。考虑到井中不同深度间隔，获得了考虑各种实验热导率条件的热流密度值以及整个钻孔的平均值。结果与以前基于干岩石的热流密度估算值相符，但更重要的是，强调对地层温度和水饱和度的影响，对于提供沉积盆地中准确的热流密度估算至关重要。对于Soultz-sous-Forêts，考虑到热岩石，计算得出的平均传导热流密度为127 mW / m2，而对于湿岩石，则计算为184 mW / m2。对于热岩和湿岩，GRT-1井中的热流密度估计分别为109和164 mW / m2。Rittershoffen井的结果表明，热流密度随深度几乎恒定，与Soultz-sous-Forêts网站的观察结果相反。我们的结果表明，侏罗纪地层的热流密度异常为正，这可以用侏罗纪沉积物中较高的放射源生热与因靠近Soultz-sous-spot的主要断层的存在引起的热扰动共同作用来解释。 Forêts地热站点。尽管需要更多数据来改善这些估计以及我们对热过程的理解，但我们认为此处估计的热流密度是URG当前可获得的最可靠的数据。这可以用侏罗纪沉积物中较高的放射源产热与Soultz-sous-Forêts地热站点附近主要断层的存在引起的热扰动共同作用来解释。尽管需要更多数据来改善这些估计以及我们对热过程的理解，但我们认为此处估计的热流密度是URG当前可获得的最可靠的数据。这可以用侏罗纪沉积物中较高的放射源产热与Soultz-sous-Forêts地热站点附近主要断层的存在引起的热扰动共同作用来解释。尽管需要更多数据来改善这些估计以及我们对热过程的理解，但我们认为此处估计的热流密度是URG当前可获得的最可靠的数据。