Drilling with mud return in seperate pipe

[Alfredo84]

I'm seeking information, published articles, etc on mud return in a separate pipe. The idea is that the mud used to get out the cuttings will not interact with the well bore. So the mud with cuttings will only be in the annulus along the BHA. The annulus above would be filled with another fluid. The image below shows the concept:

Sorry for the low resolution.