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225°C MWD Using Silicon-on-Insulator
Project Number

The goal is to improve the reliability of high-temperature electronic components found in measurement-while-drilling (MWD) tools needed to improve drilling efficiency and success rate at depths of 20,000 feet and below and temperatures greater than 225°C.

The objective is to design, build and demonstrate a permanently installed pressure and temperature sensor in a 175-200°C well and then design and demonstrate a 225°C MWD tool using a unique 225°C battery system. Both devices will incorporate silicon-on-insulator (SOI) fabrication technology into the manufacturing process for the microchips required.


Sandia National Laboratories – Project management and all research products
Diamond Research – MWD azimuth measurement tool fabrication and testing
Silicon Designs – MWD inclination measurement tool fabrication and testing
Eagle-Pitchard Industries – thermal battery commercialization partner
General Atomics – solid state battery commercialization partner

Accomplishments (most recent listed first)
  • Designed, assembled and lab tested an SOI pressure/temperature (P/T) measurement tool;
  • Installed the SOI P/T device in a Coso, California wellbore;
  • Designed, built and tested a thermal battery component of a hybrid battery;
  • Designed built and tested a solid-state ceramic cell component of a hybrid battery;
  • Built and tested an azimuth measurement device capable of operation at 225°C;
  • Prime has provided Sandia with complete requirements for installing SOI MWD electronics; and
  • Prime Direction Systems and Diamond Research and Development are in the early phases of commercial deployment of 225C MWD tool-orientation modules. Prime may provide other service companies these orientation packages.

Task 1 is underway at Coso NavalTest Range and will continue until October, 2005.The tool has been installed within the well at 3,100 ft. At this point the nominal temperature is 192°C (379°F). Prior to the tool going into the well, it was oven tested for one month at temperatures between 180 and 200°C.The purpose of this public test is to demonstrate the increased reliability gained when using manufacturer-qualified, commercially available, high-temperature electronic components. The well is one mile from the Coso Geothermal power plant. Fluctuations in the P/T will be analyzed by Navy geologists to learn more about the reservoir.

The battery proposed for Task 2 is a hybrid composed of a low cur-rent solid-state ceramic cell (25-250°C) used for retaining memory and program instructions, and a thermal battery (150-250°C) to carry the main current load. Testing of the thermal portion at 200 and 225°C demonstrated positive results.

Tests of the first plasma-sprayed solid-state battery cell show that it operates over an extremely wide temperature range; cell output was 2.79 volts at 25°C and 2.98 volts at 300°C. This was not just a test of the chemistry but also of the plasma spray fabrication process; one that it is hoped will greatly reduce fabrication costs and the internal resistance inherent to solid-state batteries. During the first test, however, the internal resistance did not improve. Evaluation of the test cell showed oxidation on the anode, most likely from exposure to air prior to assembly.

A manufacturing partner for the solid-state portion of the hybrid battery, General Atomics, has obtained exclusive licensing rites to the solid-state battery chemistry. The company has signed a Co-operative Research and Development Agreement (CRADA) with Sandia and will provide 50 percent of the cost share.

Task 3, to design, build and field test an MWD tool, is also currently underway. Tools for making two critical MWD measurements, azimuth and inclination, are being tested at 225°C.Diamond Research has completed a study of the instrument for azimuth measurement at 225°C and it appears that conventional flux-gate magnetometers and SOI analog circuits will be the best approach. Testing of the SOI inclination sensor has been delayed due to fabrication problems.

Current Status

and Remaining Tasks: 
Task 6: This task is shared by Prime Directional Services and Sandia. Prime is the lead.

Sandia will layout the electronics, making any needed temperature, shock and vibration testing. To date, this work is not completed. The new VCO A/D circuit technology must be proven reliable before moving forward. The VCO A/D circuit is approximately 12 times the size of the previous Honeywell 12 bit A/D. The VCO circuit also requires additional sensor interface circuits not yet determined.

Sandia has built an oven vibration system that is ready for testing. By May 2005, Prime will modify their existing MWD tool for the high-temperature electronics, and Sandia will aid in high-temperature seal and bearing designs.

Prime provided Sandia engineers with photos of failed face seals. Sandia is working with an outside consultant to develop a failure model and forwarding recommendations to Prime.

By August, 2005, Prime and Sandia will test and evaluate the 225C MWD tool. Prime will also actively seek a drilling demonstration partner. This activity has not yet started.

Task 7: Sept 15, 2005. General Atomics is the lead. They will provide prototypes batteries to support the Task 6, as well as a written proposal for a battery production facility.

Task 8: Sandia will maintain a website for the long-term demonstration test that started in 2003 under Task 1.

Sandia is Testing HT op amp from Honeywell project. This will be an unbiased third party testing.

Project Start
Project End
DOE Contribution


Performer Contribution


Contact Information

NETL – John D. Rogers ( or 304-285-4880)
SNL – Randy A. Norman ( or 505-845-9675)

Additional Information

Pressure and temperature plots from the test are available on the Internet at