The objective of the proposed effort will be to develop a fiber-optic sensing system capable of real-time simultaneous distributed measurement of multiple subsurface, drilling, and production parameters. A proven and breakthrough technology that enables the harmonic-free interrogation of thousands of grating-based distributed interferometers along an optical fiber will be leveraged for long distance, distributed acoustic measurements, and integrated with a novel optical sensing fiber to obtain distributed subsurface electromagnetic field measurements. A novel multi-material, measurand-specific, optical fiber will be fabricated and integrated with the sensing system to enable the distributed and real-time measurement of multiple parameters simultaneously with ultrahigh sensitivity, high frequency, and reliability at depths and temperatures beyond that of current monitoring technologies.
Virginia Polytechnic Institute and University, Blacksburg, VA 24061
Sentek Instrument LLC., Blacksburg, VA 24060
It has been estimated that the recovery efficiencies are on the order of 20% in gas-rich shale reservoirs and less than 10% in liquid-rich plays. Critical knowledge gaps in the understanding of subsurface hydraulic fracture geometry and optimal completion/stimulation strategies continue to limit the most efficient recovery of Unconventional Oil and Gas (UOG) resources. Limitations of currently available technologies to characterize and monitor relavant subsurface features present a major obstacle to understanding the in situ nature of hydrocarbon occurrence and the resultant flow properties of the stimulated reservoir as well as controlling the stimulation and production.
Next-generation logging tools that can image radially from the borehole with high resolution, seismic sensor arrays to monitor stress near the wellbore, and methods to remotely characterize fluid flow are actively sought to assure efficient production. Although several schemes (such as wireless data telemetry, electronics-based technologies, and fiber optic sensors) have been investigated, insufficient performance has limited their widespread efficacy in UOGs. Furthermore, the use of more than one of these technologies to obtain the necessary information further complicates the deployment and is often not feasible because of the stark difference in operating principles and integration procedures. There is a clear need for innovative and breakthrough technologies for improved subsurface characterization, visualization, and diagnostics to fill data gaps in big data analytics to inform decision making and improve ultimate recovery of UOG plays.
The project will demonstrate a ground-breaking technology to view the subsurface with unprecedented clarity, enable real-time facture diagnostics, and optimize drilling and production via the rapid, distributed, and simultaneous measurement of subterranean seismic and electromagnetic phenomena. A one-of-a-kind distributed fiber optic acoustic sensing system will be coupled with a transcendent magnetic fiber optic sensing fiber that will provide seismic and electromagnetic measurements with contrast, spatial resolution, and functionality not yet realized by other techniques. It is envisioned that the simple, minimally invasive, compact, and cost-effective approach will aid in the ultimate recovery from UOG resources and optimal use of the Nation’s subsurface resources, particularly for the small profit margins and fast turnaround time required for decision-making at these sites.
Activities planned for the coming months include the characterization of the reduced diameter (~80 micron) optical fiber, evaluation of the response of the magnetic sensing fiber to transverse magnetic fields, and characterization of the EM radiation/electric field response of the magnetic sensing fibers. In the next 12 months, the primary goal is to secure funding for field trial testing (3-year program) of the sensing system in a representative downhole environment. To meet this goal, theoretical analyses of prospective applications will be performed, the work will be published in peer reviewed journals, and potential government funding agencies will be engaged. As time and funding permits, a magnetic sensing fiber with high concentrations of Metglas nanowires (<100 nm) will be fabricated and the minimum detectable magnetic field strength will be determined. The data analysis techniques will also be further refined to enhance the results of the magnetic sensing fiber calibration.