There is no concrete. Cement is used to seal the casing (the metal pipe, which is this context isn't called tubing, that's something else) against the formation.
Correct on both. It's obviously been too long since I've had an association with the business. The pipe used for casing a well is called casing or casing string. Tubing is the pipe that is inserted in the casing when producing form the well.
In my business, the technical difference between pipe and tubing is how the diameter is measured - it has nothing to do with the application in which it is used. Tubing is measured by the outside diameter, while pipe uses
nominal diameter. For instance, a 1-inch tube has an outside diameter of 1-inch. The outside diameter of pipe varies depending on the type; however, 1-inch nominal
steel pipe has an outside diameter of 1.315 inches. The inside diameter of 1-inch pipe depends on the wall thickness, and the wall thickness is defined by the pipe's
schedule. For example, schedule 80 pipe has a thicker wall, and therefore can withstand a higher internal pressure, than schedule 40 pipe.