As geothermal reinjection has been required in the rapid development of geothermal industry market, geothermal heating projects are in badly need of recoverable geothermal resources assessment for target areas feasibly and reasonably. This paper proposed a simplified method of assessing recoverable geothermal resources for a doublet well production pattern. The assessment method was based on the analytical investigation of computational method of influence area when water flows through and extracts heat from geothermal reservoirs. The model was validated and verified by comparison with numerical simulation results. This method has been applied to assess recoverable geothermal resources and district heating potential of lower Minghuazhen Formation in Bazhou, Hebei province, China. This resources assessment method can provide the accurate recoverable geothermal evaluation results based on the optimization extraction-reinjection strategies for efficient decision-making of geothermal projects. With the help of the simplified geothermal resources assessment method, geothermal heating enterprises will adapt to the rapid development of geothermal industry by reducing time and cost of geothermal heating projects.