Shell turns to cascade lasers for oil exploration
A UK team is working on a £2.4 million ($4.5 million) project to develop an optical system based on quantum cascade lasers for oil and gas prospecting.
Comprising the III-V foundry Compound Semiconductor Technologies (CST), the Universities of Sheffield and Glasgow, Shell Global Solutions and laser system specialist Cascade Technologies, the consortium has received just over £1 million from the UK government's Department of Trade and Industry (DTI).
The industrial partners are providing the remaining £1.4 million. Energy giant Shell will fund field testing of the instrument once the development is completed.
The detection system will be based on photoacoustic spectroscopy (see link), a technique that can be used to measure gas concentrations with remarkable sensitivity.
CST commercial director Wyn Meredith explained that ethane (C2H6) is the crucial hydrocarbon that gives a strong clue as to the likely location of an undiscovered field of oil or gas.
Ethane and methane (CH4) gas are produced when larger hydrocarbons - typically found in oil and gas reserves - crack into smaller molecules. Unlike methane, however, ethane is not produced by biological decay, and so it is a far more reliable indicator.
QCLs allow instrument size reduction
Shell already uses a system based on a mid-infrared lead-salt laser to probe for ethane in its so-called "LightTouch" prospecting equipment.
However, these relatively bulky lasers require cryogenic cooling, and the mobility of the system can be an issue. By incorporating III-V-based quantum cascade lasers (QCLs) instead, the size of these systems could be greatly reduced.
"Using the photoacoustic spectroscopy approach, we hope to produce an instrument that has an ethane sensitivity of around 100 parts per trillion," said Meredith.
Researchers at the University of Sheffield will be growing QCL structures using novel antimonide-based epitaxy to reach the crucial 3.35 µm absorption band of ethane. The material development is needed because commercial QCLs that are currently available operate at longer wavelengths than this.
Using designs developed with the electronics and electrical engineering department at Glasgow, CST will fabricate laser devices from the material produced at Sheffield, while Cascade will provide module-level packaging and control electronics.
Glasgow's physics department will then develop the photoacoustic instrument in conjunction with Shell until it is ready for field trials.
"The long-term aim is to set up a UK supply chain - from design to packaged device to system implementation," explained Meredith. "This is strengthened by Cascade securing the rights to source QCLs from foundry manufacturers." Cascade and Lucent Technologies recently signed a deal over the intellectual property relating to QCL devices (see related story).
While QCLs are only in the very early stages of commercial deployment, they could end up being as useful to cancer specialists as they may be to oil prospectors.
That's because ethane gas and other hydrocarbons are also produced when cancer causes free radicals in the human body to break down cell membranes.
With applications in fuel exploration and medicine set to complement the current market drivers of industrial safety regulations and homeland security, CST is now looking at a number of III-V device technologies that could turn into a valuable business opportunity for the foundry over the next five years.
"Once the baseline technology is established, the foundry model will allow rapid prototyping of novel designs for new product development, and embed this technology firmly in the UK," Meredith concluded.
