No Molecule Left Behind:

Monitoring Reservoir Production

To maximize energy production from existing fields, we need to understand how fluids are moving in the subsurface. Producing reservoirs (oil, gas, geothermal) are dynamic, and as fluids are produced over time the reservoir pressure and fluid distribution changes. Reductions in reservoir pressure may result in the compaction of geologic intervals and, depending on the depth of the producing interval, surface subsidence.

Production and injection of fluids may also cause stress changes that re-activate existing faults resulting in the generation of small microseimic events. Finally, changes in pressure or fluid distribution may cause changes in the seismic velocity or attenuation that can be detected and interpreted through the use of repeated 3-D seismic surveys (referred to as 4-D seismic). All of these measurements provided detailed information about fluid movement that can be used to maximize recovery.

At ERL we currently have a major reservoir monitoring project that combines surface subsidence and micrseismic monitoring to analyze changing reservoir conditions in support of the field production and development plan. The surface subsidence monitoring uses a dedicated network of GPS sites over the field, while the microsesimic monitoring uses a combination of surface and downhole seismic sensors. Integrated geophysical monitoring of producing reservoirs provides a means of imaging the reservoir dynamics to allow optimal production.