The objective of the project is to develop, prototype, and test a robust multi-component sensor that combines Fiber Optic and Micro-Electro Mechanical System (MEMS) technologies for use in a borehole seismic array.

Paulsson Geophysical Services, Inc., Brea, CA
Optiphase, Inc., Van Nuys, CA
Micralyne, Inc., Edmonton, AB, Canada
Davidson Instruments, The Woodlands, TX

This project addresses the challenge of imaging deep and complex gas reservoirs. Surface seismic imaging is the industry standard, but it does not provide sufficiently detailed images of complex or deep reservoir targets. Borehole seismic imaging can improve image resolution, but specialized sensors are needed to withstand the pressure and temperature conditions encountered in deep wells. Combining fiber optic and MEMS technologies enables a dramatic increase in the number of sensors that can be deployed simultaneously in a borehole seismic array.

Results
During Phase I, the project team designed a prototype of a 3-D fiber optic MEMS sensor. The initial design was completed in September 2005 for the first all-fiber optic downhole seismic receiver system. Unlike all other receiver strings, it will operate with no electronics in the borehole, which eliminates the need to send power downhole. An agreement was reached with Optiphase to design and build the telemetry for the system and with Davidson and Micralyne to design and build the sensor prototype. The multicomponent sensor will be equipped with 3 orthogonal MEMS accelerometers on a 1 x 1 x 1 cm cube. Each accelerometer will be a micromachined quartz wafer with a hinged flap that accelerates in response to ground motions and is equipped with an optical interrogation system that measures the magnitude of the acceleration. In November 2005, Paulsson and Optiphase completed the initial design concepts for the optical interrogation system to measure the magnitude of ground acceleration. The prototype sensor design was completed in May 2006, with targeted maximum operating temperatures of 350-400 °F and maximum operating pressure of 25,000 psi.

Benefits
This project should advance the state of the art in borehole seismology by developing high-pressure and high-temperature components for a digital sensor system. The sensor could become a reliable component of future vertical seismic profile receiver arrays. Such arrays should result in better image quality for characterizing deep gas targets. If successful, this technology should increase the success rate for deep gas wells and decrease the risk of missing a deep gas target.

Summary
The aim of this project is to develop a sensor that can be used in borehole seismic systems designed for deep wells. By combining the fiber optic and MEMS technologies, the resulting sensor should be able to withstand 350–400 °F and 15,000–25,000 psi, sustaining its reliability in both shallow and deep wells.

(February 2008)
Optiphase has outlined the fiber optic system. Optiphase analyzes, procures and characterizes vendor and hardward components.

The project is complete. The final report [PDF-2.43MB] is now available.

Funding
The project was awarded in October 2004 under NETL’s Deep Trek program, which is designed to improve the economics of high-pressure, high-temperature wells.

$1,204,538

$1,204,538

NETL – Frances Toro (frances.toro@netl.doe.gov or 304-285-4107)
Paulsson Geophysical Services, Inc. – Paulsson, Bjorn (bjorn.paulsson@paulsson.com or 562-697-9711, x101)

Final Report [PDF-2.43MB]