| Title | Numerical Simulation of Calcite Scale Removal by Chelating Agents Around a Geothermal Injection Well |
|---|---|
| Authors | Tianfu Xu; Rose, Peter; Pruess, Karsten |
| Year | 2008 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Geothermal Injection Well; Chelating Agents; Calcite Scale Removal; Porosity Enhancement; Reactive Transport Modeling |
| Abstract | Geothermal injection wells are often drilled into formations containing calcite. Injecting chelating agents such as ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA), could be effective for calcite dissolution and porosity enhancement around a geothermal well. This may overcome the problem that mineral acid (such as HCl) dissolves first-contacted minerals aggressively while leaving much of the rest of wellbore untreated. The reactive chemical transport modeling method is used to investigate the effectiveness of injecting chelating agents. The well configuration and data for hydrogeological conditions were taken from the Tiwi geothermal field, Philippines. Results indicate that calcite dissolution occurs significantly close to the injection well. The degree of the dissolution is gradually decreases along the flow path. Calcite dissolution increases accordingly the reservoir formation porosity, than the permeability could be significantly enhanced. Sensitivity regarding hydrological and chemical factors is discussed. Chelating agents could be potentially used for chemical stimulation of an EGS with calcite present. |