Processing is a key differentiator to Sigma Cubed’s microseismic offering. The processing group at Sigma Cubed is focused on developing best-in-class processing tools and algorithms and constantly works to evolve these tools to deliver the most from the data. Real-time is an area where Sigma Cubed excels. Acquisition quality control and processing provides answers in the shortest time possible, providing the biggest impact on completions by using microseismic data to do adaptive fracture management during the completions job. The processing team also has deep experience in working with non-standard acquisition and integrating downhole, surface, and fiber-optic data, including in real-time.
Other microseismic vendors create multiple velocity models along the wellbore often using simplistic layer based ray-tracing, and perform user dependent manual velocity adjustment to fit perforation travel times. The problem with this is that multiple models are being created to satisfy parts of the data, but may not necessarily be geologically relevant. Location artifacts can be readily introduced, leading to a miss-interpretation of the completion.
Sigma Cubed creates the velocity model that is best suited for each project, which includes the option of a unified/single 3-dimensional anisotropic model. Utilizing the event locations allows for a wider azimuth and offset control points to help constrain the model away from the treatment lateral. All available data can be incorporated, including horizons (structure), well logs, borehole-seismic and seismic volumes.
In conventional seismic processing workflows the processing parameters are fixed, often tuned based on an analysis of a sub-set of the data. In a microseismic survey the source characteristics are varied, the noise changes over time, the distance of each event to each geophone varies and thus the optimum parameters for analyzing the signal are not fixed. Sigma Cubed is the only company to employ a fully adaptive approach to signal processing. Each event and each arrival is analyzed on a receiver by receiver basis, be it recorded on surface array, downhole, or fiber data.
Adaptive noise attenuation is a key tool applied in our signal processing. Components of noise can turn out to be predictable in time and/or spatially correlated. Predictive and adaptive filtering is all about estimating and removing this noise while preserving the signal. Optimal array design coupled with adaptive array based processing techniques are able to extract more signal, detect more events, and extract more information from the data, in even the most challenging of noise environments.
Baseline microseismic results are the event locations. However, these “dots” are just points in space and time, and do not necessarily give you a full understanding of how the rock behaved during the completion. Moment Tensor Inversion (MTI) provides the orientation of slip-plane and direction of slip of the fractures.
Sigma Cubed inversion of the microseismic data is able to extract Moment Tensor information even when the Moment Tensor is poorly constrained by limited array coverage. Operators then use MTI to understand what fractures are induced and which ones are tied to natural fracture networks and faults.