| Title | Successful stimulation of geothermal wells through hybrid acidizing techniques |
|---|---|
| Authors | Tellez, Fernanda; Quevedo, Manuel; Milne, Arthur; Exler, Ariel; Maldonado, Rommel; Cornejo, Sergio |
| Year | 2014 |
| Conference | Indonesian Geothermal Association Conference |
| Keywords | Geothermal Wells, Acid Fracture, Matrix Stimulation, Hybrid Technique |
| Abstract | Mexico, the world’s fourth largest producer of geothermal energy, generates 965 megawatts (MW) of electricity. This production comes from a number of different fields,although the Cerro Prieto field alone produces 720 MW. However to maximize the steam production it is often necessary to perform acid stimulation treatments. The temperature and mineralogy of the naturally fractured volcanic formations and scaling tendency of the produced water present some unique challenges. The potential of many geothermal wells is limited by formation damage. Drilling fluid invasion, fines migration, silica plugging, and scaling being the most common. For this reason characterization of the formation mineralogy in the producing wells is key to stimulating the wells and improving the production of steam. Mineral scale deposition occurs in the wellbore or in the natural fractures through which water is either injected or produced. In producing wells, the composition of scale is dependent on the mineralogy of the metamorphic formation. In injection wells, the scale is dependent on the composition of the injected water. With limited information regarding the mineralogy of the scale and the formation, many conventional matrix treatments are unsuccessful. To address the challenges of stimulating volcanic formation, a hybrid design methodology combining sandstone and carbonate acidizing techniques has proved to be successful in treating geothermal wells The treatments are further customized for each field to account for the differences in the mineralogy. The final fluid composition is often very different from that used to treat conventional sandstone and carbonate reservoirs. The hybrid design methodology has been successfully used to stimulate more than 20 wells in Mexico in a number of different fields including Los Humeros (Puebla), Cerro Prieto and Tres Vírgenes (Baja California), and Azufres (Michoacán). The results of these campaigns demonstrate that it is possible to consistently improve the productivity of geothermal wells and fluid admission of injectors through the use of a correctly designed treatment |