28. Subsea Positioning

For Offshore wells, the accuracy of the well coordinate is based on the accuracy of the surface and underwater positioning systems. These days, the surface positioning is invariably done using DGPS and this contributes very little (<1m) to the overall accuracy. However, this accuracy only describes the accuracy of the DGPS antenna position. This will not therefore be the accuracy of the final wellhead position.

This section describes the process and the likely accuracies of the process depending on water depth.