ISSN 1000-3665 CN 11-2202/P

    基于兰州断陷盆地地热地质条件的石佛沟地热资源潜力评估

    Evaluation of geothermal resource potential in Shifogou based on geothermal geological conditions of the Lanzhou faulted basin

    • 摘要: 针对兰州石佛沟景区地热地质条件勘探研究程度较低,严重制约当地地热资源开发利用这一问题,在充分搜集整理已有资料的基础上,总结了兰州断陷盆地地热地质条件和热储特征,结合可控源音频大地电磁测深法(CSAMT)探测结果,推断了盆地东部南段石佛沟的地热资源开发潜力。结果表明:(1)分别以深沟桥(F5)、雷坮河(F8)隐伏断裂为界,兰州断陷盆地地热地质条件具有明显差异性,可分为西部西固城区、中部七里河区、东部城关—石佛沟区;(2)平面上由西向东不同深度的热储温度呈增加趋势,垂向上2000~2500 m深度的地热增温率升高,可推断为兰州断陷盆地地热开采的基本深度;(3)东部南段的石佛沟景区潜存层状传导型地热和断裂带状地热资源,层状地下热水赋存于兰州断陷盆地南部边缘地段,断裂带状地下热水赋存于F2断裂破碎带或F2与F8断裂的交汇地段,据此推断在石佛沟景区可能存在层状和带状“复合型”地热水的富集地段。研究建议断裂带状热储层的地热水勘探开采井深度可按800~1100 m考虑,“复合型”层状热储层的勘探开采井深度可按1500~2000 m考虑;预测该地段地下热水井口出水温度可达50~60 °C,单井涌水量可达500~1000 m3/d,热水水质可达到医疗洗浴质量标准。结果可为当地地热资源勘探和开发利用提供依据。

       

      Abstract: Aiming at the problem of low degree of exploration and research of geothermal geological conditions in the Shifugou area, which seriously restricts the development and utilization of geothermal resources, on the basis of available data, the geothermal geological conditions and the characteristics of the thermal reservoir in the Lanzhou faulted basin are summarized. Combined with the exploration results of the controlled source audio frequency magnetotelluric (CSAMT) method, the potential of geothermal resources development in the Shifogou area in the southern part of the basin is inferred. The results show that (1) the geothermal geological conditions in the Lanzhou faulted basin are obviously different. Taking the buried faults of Shengouqiao (F5) and Leitai River (F8) as the boundary, respectively, the faulted basin can be divided into the western Xigu district, central Qilihe district and eastern Chengguan-Shifogou district. (2) The geothermal temperature increases from west to east, and increases vertically from the depth of 2000 to 2500 m, inferring that this is the basic depth of geothermal exploitation in the Lanzhou faulted basin. (3) In the southern section of the eastern part may exist layered-conductive geothermal resources and fault-zone geothermal resources, it is inferred that there may exist “combined type” of layered and banded geothermal water in the Shifogou district, which is located in the F2 fracture zone or the intersection of F2 fracture zone and F8 fault zone. It is suggested that the exploration and production well depth of geothermal water in the faulted-zone thermal reservoir should be considered as 800−1100 m, and that the exploration and production well depth of the “combined” layered thermal reservoir should be considered as 1500−2000 m. The wellhead geothermal water temperature in this area is expected to reach 50−60 °C, the single well yield can reach 500−1000 m3/d, and the quality of the geothermal water can reach the standard for medical bathing. The results can provide a basis for geothermal resources exploration in Lanzhou.

       

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