重力方法在太原南部地热开发中的应用

物探方法于已广泛应用地热能资源开发。太原南部地热开发方式是利用深部地热资源进行循环水供热，因田庄断裂垂向断距＞1 500 m，是影响太原南部地热资源分布的重要因素，其下降盘含热层深度＞4 000 m，开发成本极高，因此需要利用地球物理方法查明断层位置及走向。在城市进行物探工作，方法选择是需要考虑的关键因素之一，因此选取以重力为主、地震方法或CSAMT方法验证的方案。田庄断裂较为陡立，利用经2个已知孔剖面的重力水平一阶导数求取上断点位置，再利用剖面追踪布设方式确定断裂走向，结合CSAMT方法及已知钻孔资料综合拟合新生界覆盖层厚度。结果表明：田庄断裂由北东东向转北东向，田庄村东侧发现断裂错位，且方向发生改变；研究区东北—西南方向，沿田庄断裂覆盖层厚度逐渐增大。断裂位置及新生界厚度得到了西-GXWL探-1孔及后期施工钻孔的验证。

Application of gravity method in geothermal development in southern Taiyuan

Geophysical methods have been widely used in developing geothermal energy. The circulating water heating in southern Taiyuan depends on deep geothermal resources. The vertical fault distance of the Tianzhuang fault is > 1 500 m, which is an important factor affecting the distribution of geothermal resources in the southern part of Taiyuan. The depth of the hot zone of the downthrown side is > 4 000 m, and the development cost is extremely high. Therefore, geophysical methods are needed to judge the fault location and trend. Method selection is one of the key factors to consider in urban geophysical survey. Therefore, the scheme based on gravity, seismic method or CSAMT method is selected. The Tianzhuang fault is relatively steep, thus, the horizontal first-order derivative of gravity of the two known pore borehole profiles is used to obtain the position of the upper breakpoint, and then the profile tracking layout is used to determine the fault strike diretion. Moreover, Cenozoic covering layer thickness fitting is comprehensively determined by using the CSAMT method and known borehole data. The results show that the Tianzhuang fault changed its direction from NEE to NE, and its dislocation was found to the east of the Tianzhuang Village with changed direction. The northeast-southwest coating of the study area was gradually thickening along the Tianzhuang fault. The position of the fault and the Cenozoic thickness were verified by the Borehole Xi-GXWL-Tan-1 and later construction drilling.