Forecasting reservoir performance by mapping seismic emissions
Streaming depth imaging (SDI) is a modified version of Kirchhoff migration that images the intensity and distribution of weak seismic waves emitted from rocks at depth. These images reveal the locations of the fractures and fracture networks in the reservoir. SDI allows for more informed forecasts for drilling, hydraulic fracturing, and reservoir management than is provided by traditional microearthquake mapping methods. Using passive data from surface and near-surface geophone grids, SDI integrates the seismic emissions over time to form the fracture activity volume. The fracture systems and the active production volume (APV) of the reservoir are calculated from this activity volume. In situ wellbore measurements indicate that the preexisting fracture systems in the reservoir rocks have substantial impact on the placement of the fluids during the hydraulic fracture treatment. They also strongly influence the locations of maximum oil and gas production and the decline rates of resource production. Mapping the fracture systems in the reservoir before drilling provides a strong forecasting value for optimal production sites for well placement. SDI can forecast hydraulic fracturing performance and improve the estimates of resource production volumes. Mapping the activity volumes during hydraulic fracturing shows the placement of the fluids during the treatment. SDI helps forecast the locations along the well that will have the best production. Time lapse mapping of the APV periodically during production shows the zones that are producing fluids and how they change over time. Our case histories indicate that this new seismic method has great promise for improved management of unconventional resources.