Ooops My Bad

Ah, teach me not to look at the computer with bifocals instead of my computer glasses. I did not notice the spiral weld in the original photo and thought that the lack of collars just meant it was salvaged casing. My appologies for misidentifying it as casing.
Chris is right about the problems with welded pipe and machining.
There are a large number of different kinds of tubulars used in the oil patch.
Drill pipe is not left in the hole, so other than replacement of worn out material, it would not be a large component of the shipments to the San Juan oil fields.
Tubing, is the pipe installed inside the casing for the oil and gas to flow to the surface in, and would account for a large part of the smaller diameter paipe shipped in.
As mentioned, Casing is also left in the hole to line it and is larger.
And there would have been large amounts of smaller diameter flow line pipe for connecting well heads to the tank farms and pipelines.
So, during the pipe hauling boom, all sorts of tubular goods would have been represented and called "oil field pipe"