This is the second in a series of short webinars about the VelPAK and Velit Wizard tool from Equipoise Software. ([ Ссылка ]) The previous webinar gave an overview of how the Wizard works, and we pick up this webinar using the same model data.
In this webinar we will look at one interesting aspect of the software, which is depth converting with seismic velocities and calibrating the seismic velocities to the well layer information.
Typically, seismic velocities vary significantly from the corresponding well velocity measurements. If we are to take advantage of the consistent lateral control that seismic velocities give us across our surveys, we need to calibrate them to the well velocities.
There are numerous ways of calibrating seismic velocities to wells, but a simple and effective method is used by the wizard for direct depth conversion, which is a three stage process.
First, if you are using staking velocities, you convert them to interval velocities using the Dix equation. You then do not need to worry about post-Dix anisotropic scaling, as this is done in the calibration, so the scaling factor is set to 100% automatically.
You may then need to smooth the seismic velocities, especially if they are stacking velocities, as they are inherently noisy.
You then depth convert using the seismic interval velocities to create a seismic depth surface. The isopachs from this layer are compared to the well layer thicknesses defined by the formation tops, and an average calibration factor is computed. You can then back calculate scaled interval and average velocity grids so that your information is consistent in the model.
You then have the option to finally computer the mistie between the well tops and the depth surface, generate a residual correction surface and apply this to the depth conversion. This guarantees that the final depth surface will honour the formation tops. Follow this link to see our previous videos on the Wizard Tool [ Ссылка ] or head to our Velit page for more information [ Ссылка ]
