Well head or fill pipe?

Greetings Americas Elite Inspectors…recently in an inspection I encountered this pipe protruding from the ground, close to the foundation, which I assumed to be the well head (house has shallow well pump inside) since it was in the place designated ‘well’ in the disclosure, and approximately where the well pipe exited the home. The buyer indicated that he was afraid it might be a buried abandoned tank and I said its well. Later, acting on the knowledge that I never ‘know it all’ and I’m not too familiar with shallow well, its mostly four inch around here…I got to questioning and went back and took these pics and checked closer. I can not find any for sure indications on anywhere of how to tell a buried tank, and dont really know what a shallow well head should look like. There is no ‘vent pipe’ that I can see but that could have long ago been cut off. There are no leftover supply lines that I can find in the basement by the pump (where they would have probably come in to supply an old fuel oil furnace etc) so the pics arent that great, tried to get a close up of the cap but theres no words suggesting ‘fuel’ or ‘well’ specifically. I hoped perhaps somebody is more familiar with these items and can put my mind at ease. Well head…or fill pipe? also took a pic of the orientation by the house.
mike in MN

Hand pump casing cover according to the patent #.

http://www.freepatentsonline.com/2657633.pdf

Baker Monitor