Two deep geothermal wells, one of which is the deepest onshore UK well, have been successfully drilled to intersect the Porthtowan Fault zone in the early Permian high heat flow Carnmenellis Granite, part of the major post-Variscan Cornubian batholith which underlies SW England. The drilling target was prognosed at 4 to 5 km depth from existing surface data and limited geophysics. It is a late Variscan complex strike-slip fault zone with an episodic reactivation history, possibly as late as the Tertiary, and is associated with fluid flow on a geological timescale including present day geothermal springs in mines.

Logging and initial hydraulic testing have been carried out to help define the reservoir volume, where temperatures at 5 km depth are around 180 °C. Initial reservoir modelling based on the fracture data and the induced micro-seismicity during drilling and injection testing afterwards indicates that open fractures aligned close to the maximum horizontal stress at >4 km depth are in critical extension or shear and a subset of them are hydraulically active. These early results are encouraging for this project, which aims to produce power and heat, as well as for other similar geothermal ventures in the region.

两口深地热井（其中一口是英国最深的陆上井）已成功钻探到与早二叠世高热流 Carnmenellis 花岗岩中的 Porthtowan 断层带相交，该地热井是英格兰西南部主要的后瓦里斯坎 Cornubian 基岩的一部分。根据现有的地表数据和有限的地球物理学，预测钻探目标的深度为 4 至 5 公里。它是一个晚期 Variscan 复杂的走滑断层带，具有间歇性再活化历史，可能晚于第三纪，并且与地质时间尺度上的流体流动有关，包括当今矿井中的地热泉。

已经进行了测井和初始水力测试，以帮助确定储层体积，其中 5 公里深度处的温度约为 180 °C。基于裂缝数据和随后的钻井和注入测试期间诱发的微地震活动的初始储层建模表明，接近最大水平应力的开放裂缝在 > 4 km 深度处于临界伸展或剪切状态，其中一部分处于水力活动状态. 这些早期结果对这个旨在发电和供热的项目以及该地区其他类似的地热项目来说是令人鼓舞的。