Polyline

YirimamboBonyaah1

Is it best practice to always have polylines for editing your surface? I know in densely drilled areas snapping to datasets is enough, or is it? Background: There is a model I am updating with new drillholes.

SarahFurney2

In an ideal world, the drilling density would be enough that snapping to downhole data is sufficient on its own. In reality, that’s not always the case, either because drilling is too sparse or because the geology is complicated even in densely drilled areas. As the geologist, best practice is really about treading that line between logical geological interpretation and geofantasy.

I like to think of polylines as additional interpretive control. If the surface honours the new drilling and gives you a geologically reasonable result, there may be no reason to add them. If you’re getting unwanted geometry between drillholes, or need to preserve a specific interpretation, then polylines can be really useful.

Regardless, when adding polylines or structural disks to refine your surfaces, best practice is to always label them clearly as an interpretation. For example any interpretations that I would draw would always be labelled something like "SF subsurface interpretation" and I would have a comment explaining why I was adding them. That way, I could copy the GM, remove my polyline edits if I wanted, update the drillhole data, and have a fresh look at what the software did without my edits. Does it match my interpretations? Can I remove them completely now that I have more data? Or if the model got passed on, no one would be confused at where these polylines came from.

However; if you’re spending a significant amount of time trying to control a surface with polylines, or you need multiple polylines just to get the surface to work, there’s probably something fundamental about how the surface was built that needs to be reconsidered. It may be worth stepping back and exploring an alternative way to construct that surface.

PeterOshust

Well said, Sarah!