10 November, 2015

Ambient Seismic Imaging Throughout the Life Cycles of Unconventional Fields


An overview of a new ambient seismic imaging method and applications of the method throughout the lifecycles (exploration through refracing) of unconventional oil and/or gas fields.

Newly developed ambient seismic imaging methods have valuable applications in each phase of the life cycles of unconventional fields. Exploration, development planning, design of hydraulic fractures and refractures, reservoir management and production forecasting benefit from detailed three-dimensional images of natural and induced seismic activity. The method also is applied to monitor production and waterfloods in conventional reservoirs, CO2 sequestration, water influx into mines, mine stability, mine monitoring, and water or CO2 floods.

The method:
  • Produces direct images of hydraulic fractures and natural fractures stimulated by hydraulic fractures as complex surfaces and networks.
  • Can image the natural, continuous background seismicity of the earth during 3D reflection surveys and prior to frac monitoring. The resulting images are direct indicators of natural-fracture-mediated permeability.
Applications that will be discussed include:
  • Identifying natural fracture zones prior to drilling and fracing.
  • Direct imaging of both the Stimulated Reservoir Volume and the Active Production Volume.
  • Discrete Fracture Network (DFN) frac and reservoir simulation. (The images can be imported directly into DFN simulators.)
  • Inversion of the images to map reservoir stress and stress changes before fracing, during fracing, and during production.
  • Refrac monitoring.

Imaging artificial or natural seismic emissions from the earth is not synonymous with “microseismic” imaging, i.e. with imaging only earthquakes with a magnitude ≤0. Research in recent years has shown that many other types of seismic emissions occur, and that these emissions dominate the signal. Summing the total seismic emissions at each point in a rock volume over extended time periods (minutes to hours to days) produces detailed images of the distribution of the earth’s natural continuous background seismicity, of hydraulic fractures, stimulated reservoir volumes, producing reservoir volumes, and natural fractures. This e-Symposium will describe a new imaging method that images total trace energy in this manner and extracts discrete fracture surfaces from the resulting data volumes. The emphasis will be on applications of the method, but a brief high-level overview of the geophysics of the method will also be provided. Also, we will review the types of seismic phenomena and the purpose of imaging with total trace energy rather than simply searching for specific microearthquakes events.

For a more detailed description of the material that will be covered please read: Lacazette, A., Laudon, C., 2015, Technology update: Ambient seismic imaging throughout the unconventional field’s life cycle: Journal of Petroleum Technology, v.67, no. 10 (October), p. 32-35.