A New Coupled Explicit Finite Difference Model for Wellbore Flow and Heat Transfer in CO2 Geological Storage

Abstract

The wellbore pressure and temperature are very significant parameters for CO2 geological storage projects, which determine the safety and effectiveness of projects. To realize the coupling calculation between wellbore pressure and temperature conveniently, this work takes the one dimensional steady flow with homogeneous fluid in wellbores as the analysis object and divides the wellbore into finite micro-segments. Then a new coupled explicit finite difference model (EFDM) for wellbore flow and heat transfer is proposed. It is novel in three aspects: (i) the EFDM about wellbore pressure is derived from the equation of continuity for one-dimensional steady pipe flow, the equation of motion and the equation of state of the fluid within a certain micro-segment. (ii) The EFDM about temperature reflecting the wellbore heat transfer between wellbore and formation is developed according to the equation of energy balance for the same micro-segment. (iii) To realize the coupling calculation of them among the integrated wellbore, the specific method of the coupling iterative calculation between the wellbore pressure and temperature is presented. At last, a comparison among the simulation results of EFDM, other models and the log data from engineering is implemented, which demonstrated that the prediction results of EFDM are more consistent with the log data than the results of other models. Therefore, the reliability of the new coupled EFDM is verified. Generally, the prediction of wellbore pressure and temperature distribution and the comprehension about the internal essence of wellbore flow and heat transfer will be effectively promoted by this work.