Joel_Gee, Coring is when we take a cylinder of rock out of the...

Joel_Gee,
Coring is when we take a cylinder of rock out of the hole (hopefully in tact). With normal drilling, the bit grinds the rock into small cuttings that can be lifted to surface by the mud system. It's fast but the cuttings aren't big enough to do much testing. To get proper lab measurements of the rock properties (especially, porosity, permeability etc) we run core. Think of it like an apple corer if you've seen one - we get a long cylinder of rock pulled to the surface. In this case it'll be 10's of metres hopefully. The problem with coring operations is that it's like going to the dark side of the moon. While coring we can't get any wireline log measurements or correct gas readings. Once the the core is out, we will run in with a wireline logging suite usually at the TD of the well. This lets us calibrate the lab data from the core with the wireline logs over a much bigger interval.
Coring is only done in the key reservoir section as it is expensive. We have to run 5000m of drill pipe into the hole in 60m sections, core the interval (several hours) then pull to the surface in 60m intervals. Depending on the core barrel size, they will need to repeat this 2 or time times in WE-3.
Not really a risky operation but the data you get from full core allows you to absoutely pin down reservoir quality (in that well).