Looks like a grape. Whether it is a wild one sown by a bird or a deliberate planting is impossible to tell from the picture.

Thanks. Will I know in the spring. In either case, is it suitable for growing on a northfacing stone wall?

Or perhaps to cover an oil tank?

Yes, those uses would be okay. What I don't like about wild grape, at least here in NE Wisconsin, is the increasing tendency for it to be seen growing up into trees, especially conifers, with their easy-to-climb tiered branching arrangement. It doesn't "strangle" the tree as you so often read, it simply grows over the foliage, shading it out and causing the host tree to rapidly decline. As I'm a conifer lover, that really bothers me. and as I said, it appears to be an increasing phenomenon.

+oM

It will also seed around some IME. We have Concord-type grapes that seed around in various spots, probably from when this was an active farm. I weed several out of beds, the lawn etc each year, so the birds must be enjoying the fruit.

Oh yeah, for sure, seeds in easily. A real survivor type of plant.

+oM

The stem angles and branching look more like grape than porcelain berry to me.

A grape. Porcelain Berry has more indented leaves. Anyone, telling you how invasive that vine is, is doing you a favor.

OK, out it goes, and more like it. I now notice it elsewhere galloping up conifers. I don't need any more vines to control, what with the wisteria and euonymus that was planted everywhere by the previous owner. Luckily there is also quite a lot of climbing hydrangea, which is a great idea for this north facing wall...

The good news is that, where it has already climbed up into a nice tree, one can simply cut the stem near the ground, paint with appropriate concentrated herbicide, and leave the stuff hanging up in the tree be. It will eventually disintegrate. Being perfectionist and insisting on pulling it all down is both a lot of work and likely to cause branch breakage.