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InSite Design - Your solution for optimizing monitoring arrays
InSite-Design has been developed to allow the user to inspect, analyse and model seismic array designs in an intuitive way while providing access to a range of advanced tools for manipulating the data. It helps you find solutions for both hyrdaulic fracturing and induced seismicity monitoring applications.
In addition to importing arrays with a .csv file, InSite-Design has built in functionality for creating the most common array types for modelling: downhole, star, patch, grid and elliptical grid. Downhole arrays can be created using imported well geometries, given the depth of the top sensor and the spacing between sensors. Any of the arrays created in InSite-Design can be combined to test the performance of hybrid systems. All sensor arrays can be configured as either 1 component, or 3 component to make use of P and S phases, as well as source vectors.
InSite-Design also features a dedicated velocity model builder to import, create or even modify existing velocity models.
There are 2 Array Analysis tools within InSite-Design: Magnitude Sensitivity, and Location Uncertainty. Each is designed to assess the performance of a monitoring array ahead of a microseismic monitoring project by analysing the impact of the array geometry and instrument sensitivity on the convergence of the location algorithm, the expected location uncertainty and the general sensitivity to help determine if the desired monitoring goals will be met.
This process calculates the minimum theoretical magnitude for an event to be detected at each point of the monitoring space. It is assumed that all sensors have an equal noise threshold. The analysis uses seismological theory, generalised scaling relations and waveform processing principles.
User-defined parameters for the calculation are:
- Q factor: average attenuation factor for the medium between the seismic source (grid point) and the receivers.
- Density: average density for the medium between the seismic source (grid point) and the receivers.
- Velocity amplitude threshold: instrument noise level in velocity units.
- Static stress drop (Brune stress drop).
- Use an average or specified double-couple radiation pattern.
In this module the user can choose to find the minimum detectable magnitude for either P-waves or S-waves. For surface monitoring cases, the noise floor can be corrected for the effect of stacking on large arrays.
For a certain source-receiver distance and input values for Q, stress drop, noise level, and density, InSite will determine the minimum detectable magnitude by comparing the noise floor to the value of the velocity spectrum at the dominant frequency.
Location uncertainty is determined by running a Monte Carlo simulation. The Monte Carlo simulation analyses the impact of uncertainties in the velocity model and arrival pick times on the event location. Theoretical trial event positions are input using the either the 3D User Event Location, or by a 3D Positions File in .csv format for multiple trial positions. For each of the defined trial positions, InSite-Design calculates the theoretical travel times using the velocity model defined in the Velocity Model module of InSite-Design. A user-defined number of simulations are then performed randomly varying P- and S-wave velocities and arrival pick times for all defined layers with a variance defined in the ‘Monte Carlo Simulation’ interface.