Logs, as they are made

Bore Lab

You are drilling the next section of a well. As the bit goes down, watch how the logs appear:

1. Sensors trail the bit. Gamma ray, resistivity and density each sit metres behind it, so they see the rock later, and some never reach the bottom.
2. The mud log lags. Gas and cuttings travel up the annulus and reach surface tens of minutes after the rock was drilled.
3. The rock changes as you watch. Mud filtrate invades permeable sands and shales wash out, so a log depends on when it was run.

Pick a scenario and a well location, then press Drill. Try Next top to jump ahead.

In the earth section the borehole, washouts and invasion are drawn many times wider than true scale.