DE-FC26-09NT0005670

Goal
The objective of this project is to build and demonstrate the Lumedyne Technologies, Inc. accelerometer technology for microhole seismic imaging.

Performers
Lumedyne Technologies Incorporated San Diego, CA 92123
Lawrence Berkeley National Laboratories

Background
Energy needs in the U.S. and worldwide continue to grow. Estimates by the U.S. Department of Energy (DOE) and energy producing companies project an up to 60 percent increase in energy demand over the next 25 years. Domestic oil and natural gas recovery will play an important role in meeting our nation?s energy and economic security goals during that period. Enhanced oil recovery (EOR) and natural gas from tight and unconventional resources are primary targets for U.S. energy production.

In a series of reports for the DOE, Advanced Resources International suggests that domestic hydrocarbon production rates could increase several-fold with the widespread application of state-of-the-art seismic technology to image oil and gas reservoirs. Great strides have been made in processing data to obtain sharper images, but higher resolution and real-time imaging are needed for accurate reservoir modeling. Two heavily used technologies?high resolution 3-D seismic and vertical seismic profiling (VSP)?require that sensors be placed on the surface or in shallow holes (a few inches to a few feet deep) to record signals generated by seismic sources and image the subsurface. A key to obtaining high resolution data is adequate band width and signal-to-noise ratio, which requires that the sensors be placed over large areas (tens of square miles) or by placing them in boreholes.

In addition to active measurements, ?passive seismic? monitoring of micro earthquake activity induced by fluid movement and stress changes in the subsurface can be monitored given the proper signal-to-noise ratio. Seismic technology has relied on decades-old geophones. Alternatives like micro-electro-mechanical systems (MEMS) and fiber optic sensors show promise, but neither has had the bandwidth or sensitivity to replace conventional geophones. With further research and development, as is currently being undertaken by this project,these technologies can lead to systems that offer lower unit cost, higher bandwidth, and better noise levels in smaller packages that can easily be deployed on the surface or in boreholes. This approach reduces survey costs, enables ?permanent? installations (due to low cost and installation ease), and provides better data for high resolution subsurface imaging.

Recent DOE funded research suggests a "designer seismic" approach is the solution, i.e., drilling a number of strategically placed, small diameter, inexpensive microholes and permanently installing small receivers for high resolution, relatively inexpensive seismic monitoring. The need for this technology will increase as the energy industry moves toward increased reliance on enhanced oil recovery and regulatory agencies begin to require CO₂ sequestration to combat global warming. One key requirement for successful CO₂ sequestration is long-term monitoring of CO₂ movement; if seismic sensors could be inexpensively placed in the subsurface, an order of magnitude increase in monitoring capability may be possible. To achieve this objective, inexpensive drilling technology must be combined with ease of sensor installation.

Ultimately, sensors would be installed on the drill pipe and wired in with the drilling tools so that the well can be drilled and all equipment cemented in place without physically having to remove and re-insert the drill string. This ultimate ?one pass? installation would save time, reduce potential well problems, and reduce the risk of having to re drill the wellbore. In an effort funded by the DOE, Lawrence Berkeley National Laboratories (LBNL) and its partners are developing a coil tube drilling technology to install sensors in the subsurface at dramatically lower costs (25?50%) with reduced environmental impact through faster drilling time and a smaller footprint. Instrumentation of these microholes continued to be a challenge because this new technology reduced the borehole diameter from 4 inches to approximately 1 inch. Packaging and emplacement of geophones at this reduced diameter is problematic and current MEMS accelerometers do not provide the required signal-to-noise ratio. Lumedyne?s new optical MEMS accelerometer enables this new microhole drilling technique by offering an acceptable signal-to-noise ratio in a smaller package that can benefit both traditional land and seabed seismic imaging.

Impact
There is a great need for low cost, high-sensitivity, wide bandwidth sensors that can provide higher resolution spatial and temporal imaging results. It is currently too expensive to deploy large numbers of sensors for more than a few weeks, yet there is a need for ?permanent monitoring? to ?watch? critical reservoir processes develop and change through time-lapse imaging. Applications could include real-time monitoring of hydrofractures; reservoir production management (both active and passive monitoring) at resolutions of less than a few meters; fine scale imaging of potential and existing reservoirs, and much improved imaging in general. If successful, this new MEMS technology will reduce the cost of deploying seismic instrumentation to the point that surface and borehole surveys will become routine and the vision of a truly ?instrumented? oil field /gas reservoir will become a reality. This technology is meant to provide the seismic exploration and monitoring industry with a much needed ?leap? rather than a small, incremental step in performance.

Accomplishments

• Researchers have successfully transitioned from DC to AC actuation voltage, providing performance enhancement to the accelerometer.
• Researchers have successfully completed component-level optimization bench tests of the accelerometer technology.
• The loop closure electronics have been successfully integrated with an accelerometer.
• Successful electronic actuation of the proof mass with the newly redesigned electionics has been accomplished. This is a critical step in the integration of the electronics with the MEMS device and shows that the electronics are capable of providing the appropriate force feedback voltage to close the loop around the proof mass.
• Prototype accelerometers were successfully fabricated
• Accelerometer design and simulation complete
• Completed MEMS sensor design and modeling
• High level electronics design and analysis complete
• Model verification on fabricated components
• Temperature compensating resistive heater fabricated
• Prototype electronics completed
• Determination of target sensor specifications
• Resistive Heater Fabrication & Evaluation completed
• Custom Vertical-Cavity Surface-Emitting Laser (VCSEL) completed
• VCSEL Loop Closure Electronics complete
• Heater Loop Closure Electronics complete
• Improved Cap Wafer Design
• Proof Mass Loop Closure Electronics complete
• MEMS fabrication complete
• Fabrication of the MEMS die is complete
• Package Design complete
• Completion of system level analysis
• Accelerometer Design and Simulation, and Fabrication have been completed.

Current Status (May 2012)
System integration is currently underway. The current focus is on integrating the components that make up the novel accelerometer into a completed package (MEMS sensor, VCSEL, monitor diode, focusing lens, optical isolator, and AC actuator). Once completed, LTI will test and characterize the complete accelerometer assembly prior to the field testing.

Project Start: October 1, 2008
Project End: January 31, 2013

DOE Contribution: $1,256,277
Performer Contribution: $513,704

Contact Information:
NETL ? William Fincham (william.fincham@netl.doe.gov or 304-285-4268)
Lumedyne Technologies Incorporated ? Brad Chisum (bchisum@lumedynetechnologies.com or 619-602-5414)
If you are unable to reach the above personnel, please contact the content manager.