太原盆地岩溶热储地热资源评价

太原盆地断裂构造发育,地热资源丰富,是我国具有代表性的中低温地热田,故太原盆地地热资源的整体评价对其大规模的开发利用具有重要意义。以太原盆地构造演化分析、地震和电法等剖面解释、最新钻井测井解释成果为研究基础,以盆地二级构造单元为划分依据,采用“热储体积法”将太原盆地划分为8个地热田并作为评价单元。针对8个评价单元的寒武-奥陶系碳酸盐岩岩溶热储进行了精细评价。综合评价得出太原盆地碳酸盐岩岩溶热储具有热储盖层稳定、埋深浅、储集层段多、储量大等特点。表现为岩溶热储上覆盖层厚度400~2 000 m,储集层从老至新依次发育了奥陶系峰峰组、上马家沟组、下马家沟组、亮甲山组和寒武系凤山组、长山组6套主力含水层段。地温梯度一般为3~4 ℃/100 m之间,热储温度为30~80 ℃。在此基础上,根据地热田热储面积和厚度、热储温度、孔隙度、比热容和密度等参数,计算西温庄地热田地热资源量,得出太原盆地可采资源量13.84×10⁸ GJ,折合标煤4 721.9×10⁴ t,初步摸清了太原盆地的地热资源分布规律以及资源量。

Geothermal Resources Evaluation of Karst Thermal Reservoir in Taiyuan Basin

Taiyuan basin is a representative low-moderate temperature geothermal field in China,with well-developed fault structure and abundant geothermal resources.The overall evaluation of geothermal resources in Taiyuan basin is of great significance to its large-scale development and utilization.Based on the structural evolution analysis,seismic and electrical profiles interpretations and the latest well logging interpretations,the basin is divided into eight geothermal fields as evaluation units with the“thermal energy storage method”based on the secondary structural units.Carbonate karst thermal reservoirs of Cambrian-Ordovician in eight evaluation units have been carefully evaluated.The results show that the carbonate karst thermal reservoir in the basin is characterized by stable thermal reservoir and caprock,shallow burial depth,multiple reservoir sections and large reserves.The cap rocks of karst thermal reservoir result in burial depths of 400 to 2,000 m.From top to bottom,six major aquifer sections of Ordovician Fengfeng Formation,Upper Majiagou Formation,Lower Majiagou Formation,Liangjiashan Formation,Cambrian Fengshan Formation and Changshan Formation are deposited successively.The average geothermal gradient is 3.0 to 4.0℃/100 m,and the geothermal water temperatures range is 30 to 80℃.Based on that and the parameters of geothermal reservoir area,thickness,temperature,porosity,heat capacity and density,the total exploitable geothermal reserves in the geothermal field is calculated to be 13.84×108 GJ,which is equivalent to 4,721.9×104 t of standard coal.Distribution regularity and amount of geothermal resources in the Taiyuan basin is thus preliminarily clarified.