综合物探技术在深部碳酸盐岩热储探测中的应用研究——以雄安新区为例

Application of the integrated geophysical exploration technology in the exploration of deep carbonate geothermal reservoirs:A case study of the Xiong'an New Area

雄安新区地热资源潜力大,碳酸盐岩是雄安新区深部地热资源的有利储层,综合地球物理勘查方法是查明深部构造与碳酸盐岩热储特征地层结构的有效途径。本文针对深部碳酸盐岩热储勘查目标,提出了“面—线—点”分层次渐进式地球物理探测模式,先利用高精度重力和航磁资料研究碳酸盐岩分布范围及地层厚度、深大断裂分布、基岩起伏等信息,然后利用大地电磁开展热储地层低阻异常特征分析,再利用二维地震剖面精细刻画热储地层,分析地热田异常区速度结构和区域构造特征。根据重力、航磁、大地电磁、地震等地球物理方法在地热资源勘查的不同阶段勘探的精度及可靠性,以及施工成本、施工效率等因素,开展了地球物理方法探测深部岩溶热储经济适用性分析,并建议在碳酸盐岩地热勘探采用“重力+磁法+大地电磁”的地球物理勘探技术组合方式。

Xiong'an New Area has great potential for geothermal resources.Carbonate rocks are favorable reservoirs for deep geothermal resources in this area.The integrated geophysical exploration technology is an effective way to ascertain the deep structures and the characteristic stratigraphic structure of carbonate geothermal reservoirs.Aiming at the exploration target of deep carbonate geothermal reservoirs,this study put forward a surface-line-point hierarchical and progressive geophysical exploration model.Using the high-preci-sion gravity and aeromagnetic data,this model first investigated the distribution range of carbonate rocks,the thickness of carbonate strata,the distribution of deep-seated faults,and the fluctuation of bedrocks.Then,it analyzed the low-resistivity anomalies of geother-mal reservoir strata using the magnetotelluric method.Finally,this model finely characterized the geothermal reservoir strata using two-dimensional seismic profiles and analyzed the velocity structure and regional structural characteristics of anomaly zones in the geother-mal field.Based on the exploration precision and reliability of gravity,aeromagnetic,magnetotelluric,and seismic geophysical methods in the geothermal resource exploration of different stages,as well as other factors such as construction cost and efficiency,this study an-alyzed the economic applicability of geophysical methods in the exploration of deep karst geothermal reservoirs and suggested that the carbonate geothermal resources should be explored using the geophysical exploration technology combination of gravity,magnetic,and magnetotelluric methods.