Entanglement Technologies has patented a mobile optical cavity gradiometer design for precise detection of trace gas vapors. The measurement sensitivity is expected to surpass that achievable with expensive and immobile, high-end mass spectroscopy devices, while remaining economical and maintaining portability. As compared to other mobile sensor technologies, we anticipate a gain of nearly three orders of magnitude in sensitivity. This technology will have near term applications in detecting plumes of ethane and methane gas which can be used for locating oil and natural gas deposits in frontier exploration.