Calculation of Storage Capacity of Geothermal Resources by Element Weight Method: A Case Study of Lantian Bahe Formation in Xi´an Depression

This study proposed element weight method to improve the calculation accuracy of storage capacity of geothermal reservoir. This method fully exploits all geothermal wells in the calculation region, and the calculation region of every three neighboring geothermal wells was divided into many calculation elements, the whole calculation region of the distribution parameters were discretized into independent lumped parameter regions in each element, the arithmetic mean of three node parameters in each element was used as the element lumped parameter and the block with the same set of parameters was divided into calculation regions as small as possible. The effect of one element as well as its the parameters in the whole calculation region depends on the weight of area of this element in the whole calculation area. The element weight method can be used to calculate volume water storage capacity of geothermal fluid, elastic release storage capacity, geothermal storage capacity of volume water, geothermal energy storage capacity of elastic releasing water, geothermal storage capacity of geothermal reservoir rocks for each element, respectively, and then storage capacities of various elements and the entire calculation regions can be calculated through summing up. In the second part of this study, the data of 65 existing geothermal wells were adopted to calculate storage capacity of geothermal resources in Lantian Bahe Formation of Xi´an Depression by using the element weight method. If the geothermal energy recovery is set as 10%, under the current efforts of the exploitation, the geothermal energy contained in geothermal reservoir can be extracted for more than 10,000 years, while under the current conditions of exploitation technology, the mining of available elastic release storage capacity can be maintained for more than 40 years.