Observations of microseismic events detected during hydraulic fracturing treatments have provided an incentive to develop complex fracture models. Calibration of these models can be difficult when only the locations and times of the microseismic events are used. Incorporating the microseismic event source parameters into the model calibration workflow reveals changes in fracture behavior that are not easily visualized and provides additional guidance to the selection of modeling parameters.
Microseismic events occur when deformation of the reservoir and surrounding formations produces seismic waveforms. Travel-time and hodogram analysis of the recorded waveforms are used to locate the microseismic event sources while the amplitudes and polarities of the waveforms provide information about the deformation that has occurred. The geophysical property that is derived from the wave amplitudes is known as the seismic moment and is related to the area and displacement of the failure.
The relationship between seismic moment values and the deformations that produced microseismic events can be applied to engineering evaluations to identify variations in microseismic response. Use of this source parameter supplements commonly used visualizations of microseismic response where microseismic activity has been mapped. An example from a field case is included.
Mapping of the seismic moment distributions in a 3-dimensional viewer provides insights into fracture behavior that can be used to calibrate complex hydraulic fracture models. This is done through an integrated software package that facilitates comparisons of the microseismic evaluation and complex fracture modeling outputs seamlessly. Changes to the complex fracture model inputs can be evaluated quickly and easily to determine if the fracture modeling correlates well with the measured microseismic responses. Production evaluation, history-matching, and forward-modeling to test different completion and stimulation design scenarios can be undertaken with improved confidence using the calibrated complex fracture model.