Integrated interpretation: Defining risk corridors by combining 3-D seismic interpretation with induced seismicity hypocenters

Abstract

Development of a resource play is subject to intrinsic risks. These may include the risk of incurring unexpected costs or shutdowns due to anomalous induced seismicity, or risks associated with reservoir stimulation that differs from prior empirical or numerical models. These two risks may be related causally, as completion effectiveness could be adversely affected by loss of fracture fluids into fault systems and/or damage zones, irrespective of the occurrence of induced seismicity. We outline a novel strategy for pre-operational risk assessment that is guided by the interpretation of 3-D seismic data, principles of structural geology and available induced seismicity data from surrounding operations. We integrate regional seismic structural mapping with results of previous experimental studies to develop a corridor-based risk-assessment approach. This approach is illustrated by a case study from the Duvernay play in Alberta, Canada, where subtle basement-rooted strike-slip faults and associated Riedel shears have been activated during previous hydraulic-fracturing completion programs. Unlike previous case studies in this area, we combine analysis of several adjoining 3-D seismic and induced seismicity datasets in order to map regional risk corridors. Given the general infeasibility of exhaustive detection and mapping of all potentially seismogenic faults, our approach relies on established structural principles, analog settings (flower structures) and analysis of fault-slip potential to quantify the probability of activation within a defined corridor that contains interpreted faults.