| Autor: |
J. Perezyera, A. Rosas, A. García, S. Santoyo-Gutiérrez, M. Morales |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Journal of Volcanology and Geothermal Research. 47:195-208 |
| ISSN: |
0377-0273 |
| DOI: |
10.1016/0377-0273(91)90109-d |
| Popis: |
The drilling of deep wells in the La Primavera caldera has evidenced a highly complex and hazardous problematic situation due to considerable losses of drilling fluids. Such large losses have not occurred in any other geothermal field in the world. These losses are due mainly to the structural conditions of the geological formations which are penetrated. The technology employed in the construction of deep wells has played a very important role in the solution to these problems. Field case histories describe the effectiveness of the developments of drilling fluids and cement materials in cavernous formations with severe lost-circulation problems. A processed clay bentonite was developed whose high performance and rapid hydration characteristics allowed a reduction of up to 5 hours in the drilling fluid conditioning time. Also, useful results were obtained through the development of a granular plugging mixture which maintained sealing properties at 70 kg/cm2 under cavernous simulated conditions. This granular plugging mixture kept losses of the volume of drilling fluid under 8% with respect to the total volume. Special cement plugs with thixotropic behavior allowed the handling and placement of this slurry in the problematic zone. The CaSO4 addition to the cement slurry was optimized so that a placement time of 30 min could be obtained. Additionally, the mechanical compressive strength values of this special cement plug ranged from 50 to 100 kg/cm2. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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