Build a 3d Velocity Model From Checkshots schlumberger petrel

Create a rectangular polygon for grid area. Rename to suit. Open Make/Edit Surfaces and set geometry to seismic area, algorithms to Artificial Algorithms, set time to base at -5000 ms, Grid increment to 3D grid (50 0X500 ft) and check name box and name Grid Area Base. OK Open the Grid's settings and change template to Elevation Time. Copy surface and rename to Grid Area Top. Open Grid's settings and change depth of grid to 0 ms using calculations: A=0 and Z=A. QC results in a TWT 3D window. Open Make Simple Grid and select Create New... Name Grid ChkSht VelMod. Set the Grid Area polygon as the boundary (may not be necessary). Set Input Data to Insert Surfaces and insert as top and bottom the surfaces Grid Area Top and Base. Click the Geometry Tab and single click on a representative seismic volume and then click "G et all settings from selected". Reset the Xinc and Yinc to 500 to manage grid size then OK Dbl click on Layering and change then Zone 1 from Proportional to Follow Top (or Base) and the Cell Thickness to 30 ms (again to manage grid size). OK After checkshots have been merged into a single file anda average velocity continuous log created from it..... Dbl Click to open Scale Up Well Logs Click Create New Property, set input to Well Logs and Select the average velocity log created from the Merged Checkshots. OK QC results by expanding the 3D grid under the Models Tab and then the model's Properties branch and clicking on the property button. The Checkshots should appear along the path of each well. If a checkshot is missing in a well it will have to be added to the merged checkshots and a new average velocity log generated and scaled up to the grid. Open Petrophysical Modeling with a Dbl click and click the Lock icon, bottom left. Under Method for zone/facies: choose Moving Average Set the parameters. I generally leave most alone. Changing the vertical range by an order of magnitude (X 5, 10, 15 ....) smoothes the grid vertically. Click Estimate and set the min and max if appropriate. I set the min to water velocity and leave the max alone or set it to a higher value or I might set the min to water and Absolute and let the max remain 0 and Relative(%) Other can be either, due to the Layers setting and you can c an experiment with point weighting. OK QC model using the using the I, J and K icons and the VCR style buttons on the vertical tool bar at far right (make sure Petrophysical Modeling is in bold type).