Geothermal Resource Evaluation of Ordovician Karst Reservoir In East Slope of Neihuang Uplift, Bohai Bay Basin

The eastern slope of Neihuang Uplift has developed fault structure and abundant geothermal resources, and the distribution of high quality Karst geothermal reservoir of Ordovician system matches well with the demand of urban heating. The fine evaluation of geothermal resources in the study area is beneficial to the effective development and utilization of geothermal field resources. Based on the previous research results, the research on karst reservoir distribution, physical properties, geothermal temperature and hydrochemistry was carried out, and the conceptual model of geothermal field formation was established, and the amount of geothermal resources was carefully evaluated. The results show as flow:(1) The ordovician karst reservoirs are zoned in the plane and distributed in the northeast direction, with the characteristics of shallow burial in the middle and deep burial in the east and west, and the reservoir buried depth is about 800-3000m. The reservoirs are layered in the longitudinal, single well aquifers are 19-43 layers, and the accumulative water-bearing thickness is about 46.2-137.8m, mainly distributed in Lower Majiagou Formation, Upper Majiagou Formation and Fengfeng Formation. (2) The average porosity of the geothermal reservoir is about 2.57-22.7%, the average permeability is about 1-100mD, the water temperature is about 48-75℃, the water volume is about 55-140m3/h, the water chemistry type is SO4+Cl-Ca+Na, and the salinity is about 1830-3560mg/L. (3) The geothermal reservoir volume method is used to evaluate geothermal resources by the zoning and the layering. The total amount of geothermal resources in Nanle-Puyang section is 31.9 billion GJ, and the recoverable resources are 4.79 billion GJ, which is equivalent to 164 million tons of standard coal. The recoverable resources can meet the heating area of 57.94 million square meters. At present only 3.93 million square meters of development, development potential is huge.