Two significant development projects were being planned for brownfields in southeast Asia with a total of seven platforms and 230 wellbores in place. Previous drilling campaigns were conducted from 10 to 30 years ago. Hence, existing data were of variable quality and reliability.

During the design process for both fields, it was determined that there were large discrepancies and irregularities between well positioning databases. This not only complicated the anticollision situation of drilling in the congested fields but could also influence the reservoir model accuracy for determining the development target. The anticollision risks based on the existing data meant that well plans had to be "over engineered" to avoid the perceived risks while also requiring offset wells to be shut in during drilling operations. Thus, both drilling efficiency and production were affected because of the well positioning uncertainties.

A comprehensive survey management process was embarked upon by both the operator and service company to ensure that the survey databases being used by the drilling and subsurface teams were consistent and free from gross errors. This included the review of all existing survey reports, sources of platform positions, etc. to identify anomalies or gross errors. This was the first such project conducted by the operator.

This paper discusses the complete survey management validation process and also highlights its effect in allowing the safe and efficient well planning of the drilling campaigns while providing the subsurface team an accurate well positioning database to allow accurate target selection.