Yeah, we figured this out a few minutes after the post. D:I hate to disappoint you, but this is just a normal-sized oil well that happened to generate atop a tree. The oil flows down the leaves and spreads over a large area. Inside the pillar there is only a one block thick column of oil source blocks.
Yeah, we figured this out a few minutes after the post. D:
The height is counted from the highest top-most solid block. And for some reason EBXL leaves are considered solid. So the geyser is only a couple blocks tall.