Heat, corrosion and fluid conditions in geothermal wells

On top of sustained heat, geothermal wells often carry corrosive fluids, and the circulating medium is not necessarily a conductive mud. We state our limits for these wells item by item, and say plainly when a job falls outside them.

The main constraints

• Sustained heat — Not a brief peak but heat for the whole run, so electronics life is counted in effective operating hours.
• Corrosive fluids — Housing material, seals and exposed connectors all need a higher corrosion resistance.
• Uncertain fluid conditions — Without a conductive drilling fluid, some measurement methods simply will not work.

What we do about it

• Continuous operating temperature and survival temperature are quoted separately, never combined into one figure.
• Housing material and sealing arrangement are selected to suit the fluid.
• Where the fluid will not carry a mud pulse, we recommend electromagnetic telemetry instead.