Revisiting the Static and Dynamic Temperature Profiles in Geothermal Wells

Abstract

Static and dynamic measurements of pressure and temperature along geothermal wells are commonplace practices for characterization purposes in the geothermal industry. Such profiles provide good insight regarding the deliverability of the well, location of the upper and lower boundaries of the reservoir / reservoirs and etc. The static temperature profiles, for example, can be used for modeling the natural state of the system through history matching. In this study a numerical model is developed to study the parameters affecting the dynamic and static temperature profiles in geothermal wells. The model is based on mass and energy balance equations and couples the reservoir with the well and takes into account the heat losses (or gains) to (or from) the surroundings of the well. The model is validated using various analytical models in the literature. Specifically we consider the comparison between the models of Ramey, Hagoort and Wu and Pruess. A synthetic application is provided to identify key parameters that effect temperature distributions during both production and injection operations. In the application we model temperature behavior along the well for the transition from static to dynamic and from dynamic to static. Further emphasis is also given to the stabilization times. As mentioned earlier, static and dynamic temperature profiles are important given that real static and dynamic conditions are reached. Not having reached actual static or dynamic conditions could lead to wrong characterization of the system. Hence in the synthetic example provided, we also consider the parameters effecting the stabilization times of the temperature profiles.