Best elements for downhole and high temperature circuits

[ebrah]

I want to design a data-logger with PIC MCUs. This data-logger is going to work in chamber in the oil wells in the depth o 500 meters. and it is going to record temperature and pressure for 20 hours.

The pressure in that depth is about 9000 PSI and the temperature is about 130 degreeC. I want to know what kind of elements is the best elements for this project. I mean if I need a 1mF capacitor, which kind of capacitors is my best choice? Electrolytes? Polyester? Ceramics? Multi-layer? Which one is less temperature sensitive? What about the resistors? and also all the other elements.

Please shed any light you can on this issue. Any point will really highly appreciate. Does any body have similar experience?

 

[1/2dime]

If it is a one-off, why redesign the wheel? There are several manufacturers of deep-well probes.
Do you have a basic design? What are the physical dimensions of the probe? Do you want to store the info in the probe or communicate real-time with the wellhead? How are you going to power the probe?
Parts data is gleaned by reading the data sheets and selecting the most suitable parts for an application.
This is not an easy task. Good luck! E

 

[D.A.(Tony)Stewart]

Depending on any other special parameters, my first choice is ;

1. Ceramic C0G, NP0 Surface Mount, MLCC -55°C ~ 200°C
only small values (nF)
2. Rechargeable high temperature lithium-ion battery 125°C
only big values (.. Farads)
3. But you want 1 mF .. hmm

 

[jiripolivka]

Why would a reasonable designer try to locate sensitive devices like data loggers into such environment?
This is why we use cables, and special ones can survive high temps and pressures. Data loggers can be then connected to the "easier" end of such cables while processing data from remote sensors deep in downhole.