Deform/bend non-planar object over a surface

First off, I'm pretty new to blender, so I apologise if this is a basic problem/question.

I'm trying to create detail on a surface, and the most obvious way I can think of is to create a half cylinder and shrinkwrap it onto the surface. But I guess this only really works for planar type objects?

What's happening is that the cylinder is following the target surface properly, but it's totally squished flat onto the surface. I want to preserve the cylinder as it wraps over the surface.

Here's what I'm trying to do, I hope it explains it better than I can describe.

Target Object Surface:

The effect of the Shrink Wrap:

What I'm trying to emulate:

So the question is, is there a way to get shrinkwrap to do what I want, or is there a better way altogether?