Pengembangan Model Matematis untuk Memprediksi Pertumbuhan Deposisi Sulfida Dalam Sumur Panas Bumi
Scaling or solid deposition generally occurs inside the two-phase geothermal wells, so it will clog the flowing of geothermal fluid through the wellbore. Certain geothermal field encountered sulfide scaling inside the production wellbore, for example the Dieng geothermal field. The solution to overcome sulfide scaling is by doing workover operation. However, the growth of scaling inside the wellbore has never been predicted yet. The necessity for modeling the growth of scaling is important, as by knowing the scaling growth inside the wellbore, we would know the depth of scaling. Moreover, workover operation can be conducted before scaling occurs and completely fills up the production well. This study is attempted to develop a mathematical model to find solution for predicting the growth of the sulfide scaling in the geothermal well, focusing on galena and sphalerite. The mathematical model was developed by integrating the solubility-temperature corelation and two-phase pressure drop correlation in vertical production well. The outcome of this study would visualize the increasing thickness of sulfide deposition inside the wellbore per annum. Then, sensitivity analysis was applied in several parameters, for example pH, the content of Pb2+, Zn2+, bottomhole pressure and mass flowrate. The results showed that the content of Pb2+, Zn2+ and mass flowrate had an effect on the amount of deposition, whereas the change of the bottomhole pressure would also change the initial depth of deposition.