Development of an Optical-based Single Well Seismic System (OSWS) for Improved Characterization and Monitoring of Fractures in UOG Systems

The current recovery from Unconventional Oil and Gas (UOG) reservoirs is a small fraction of the Original-Oil-In-Place (OOIP). Recovery rates as low as 6-8% are referenced in the literature. To improve the recovery rates much better real-time reservoir characterization methods must be developed and deployed. Borehole seismic acquisition techniques are the most effective and highest resolution techniques to investigate complex UOG reservoirs. The characterization of the stratigraphic and structural architecture and the geological components making up these reservoirs will be dramatically improved by recording vector seismic data from clamped high frequency directional seismic sources deployed in the same vertical, deviated or horizontal borehole as an array of high-fidelity optical seismic vector sensors. This will allow for the safe and the effective development of UOG resources by mapping in real time natural and induced fractures and flows both near and far from the deployment wells. The vector sources and sensors can be deployed in either the borehole used for fracturing, providing for the highest resolution, or in a nearby borehole, providing for real time monitoring of the fracturing process. Paulsson developed an effective and high-frequency prototype borehole axial, or vertical, vibrator under the SBIR Phase I project. The vertical vibrator was tested between 10-1,600 Hz and extensively tested between 10-210 Hz and 10-410 Hz. In a small-scale field test the vertical vibrator proved to generate higher frequency data than an impulsive source deployed at the same location. Data were concurrently recorded using both standard geophones and Paulsson Fiber Optic Seismic Vector Sensors (FOSVS). The borehole 3C clamped seismic sources will be designed, built and deployed in Phase II. We plan to build a field system consisting of borehole axial, torsional and radial vibrators. The units will be tested in the laboratory, in a local field test and in a deep borehole provided by an oil company. The new clamped seismic sources will be designed to be deployed using our small diameter drillpipe deployment system concurrently with our existing optical clamped 3C receivers providing for an industry unique 9C single- well seismic capability. Commercial Applications and Other Benefits: Accurate mapping and monitoring of the geology and the fractures in UOG systems will significantly increase recovery of the vast resources present in these reservoirs. Paulsson will achieve this with the proposed 9C single-well seismic system. A single-well seismic system can map and monitor faults, natural and induced fractures and salt-domes at a large distance from the wells in UOG, conventional oil reservoirs, geothermal reservoirs and CO2 storage reservoirs.