Hi, agree with X. violacea.
Note however, there are 5 Xylocopa species in Portugal: Xylocopa ameadei, X. cantabrita, X. iris (ssp. uclesiensis), X. valga and X. violacea. The first two are brownish looking species (due to pale pubescence covering the body), whilst the last 3 are all black and indeed similar. The 2 yellow segments visible on the antennae of the OP photo are unique to X. violacea I think (the other 2 species having all black antennae). X. violacea is also by far the most common species.