Q-p curve equation of geothermal well recharge test in the urban area of Mei County, western Guanzhong

Clarifying the relationship between recharge pressure (p) and recharge volume (Q) is crucial for regional green and sustainable geothermal development in geothermal well recharge. The preliminary data of well G102 recharge test in Mei County in the western Guanzhong area were optimized, and three sets of data were determined to clarify this relationship. According to the data, the Q-p curve was drawn. Based on the characteristics of five types of curves in the pressurized water test, it was judged that the curves might be parabolic, logarithmic, and hower function. Therefore, three types of curves were drawn, and the difference method was used to judge the type of curves. On the basis of the result, the parameters of the correshonding equation were obtained by the equalization error method. According to the maximum deviation of the average value of the previous recharge data, the allowable maximum absolute error range of recharge was determined, which finally went through the late example verification and error analysis. The results are as follows. First, in this area, the calculation result of the equation deduced by this method does not exceed the absolute error range allowed by the recharge volume compared with the actual situation. Its relative error deviation is small, which can satisfy the evaluation of recharge volume in the recharge test. Second, the relative error has the characteristics of decreasing first and then increasing. This feature is related to the reservoir’s saturation, pressure, and non-uniform rock mass, which is beyond the constraints in the equation. Third, combined with the test results of other recharge wells in the study area, the Q-p curve is determined as a power function type when the main recharge strata in this area are a wide flat group. The research results can provide a scientific basis for the further effective development of geothermal resources in this region.