| Title | Development and Application of a Multiphase Reactive Transport Model for the Scaling of Geothermal System |
|---|---|
| Authors | LIU Lihua, LI Dedong, ZHAI Haizhen |
| Year | 2020 |
| Conference | World Geothermal Congress |
| Keywords | Multiphase flow, geochemical model, scaling of geothermal well, Yangbajing Tibet, simulation |
| Abstract | A multiphase (gaseous, aqueous and solid phases) reactive transport model has been developed. The model combines the Hagen-Poiseuille equation which describes the mass rate of flow and the conservation of mass in round tube. The model could describe the annular and bubbly flow of a multiphase transport system under varying temperature and pressure conditions. The transport model was coupled with a self-developed geochemical model which calculates and predicts quantitatively the vaporization/condensation process of aqueous fluid and the dissolution/precipitation process of scale mineral in the multiphase system. The numerical method and computer program are used to obtain the solution for the coupling model. Above simulation tool and numerical method could theoretically model the scaling of a geothermal system in pipe line. In this work, we studied the extract process for an geothermal vertical well by this conceptual simulation tool under the environmental and geochemical condition of Yangbajing, Tibet, a famous geothermal field for its abundant geothermal energy and the severely scaling. The scaling processes and the thermodynamic and geochemical mechanism of scaling have been revealed in detail. The scaling could be initially appeared under 100 m deep of the well, and the scaling layer could be 0.017 m thickness after 24h pumping geothermal water. Thereby, it is indicated that the couple simulation tool could be used for the design of the descaling/antiscalling system and technics as well. |