Study on Heterogeneity of Carbonate Heat Reservoirs in the Southwest of North China Platform

Abstract

Carbonate heat reservoir is one very important type of geothermal reservoirs, which reservoir space are dissolved pores, holes, cracks, etc. The heterogeneity of carbonate heat reservoir refers to that its distribution characteristics and development of dissolved pores, caves, cracks and the connectivity of cracks in carbonate heat reservoir vary with space, it has an extremely important impact on the water-richness in carbonate heat reservoir. In this paper, the heterogeneity of carbonate heat reservoir in the southwest of North China Platform is studied in detail, which results show that the pores and fractures exist in a large amount, the reservoir connectivity is good in the carbonate exposed area where the groundwater is replenished, but in the deep carbonate areas, the amount of carbonate pores and fractures is less than that of the exposed areas. Also the water pumping test shows that the water-richness of carbonate is very low in the deep carbonate area. We think that the most important factor leading to the difference in water-richness between in the deep carbonate area and exposed area is the strong heterogeneity of carbonate, which poor connectivity of the fractures makes groundwater not be effectively replenished by the water source in the distance. For the exploration and development of carbonate heat reservoir, to judge the water-richness of carbonate reservoirs, it is necessary to study the influencing factors, especial heterogeneity. The heterogeneity of carbonate has a great impact on whether geothermal resources can be achieved large-scale development, therefore, the study on carbonate heterogeneity is the key link.