Yes, PORTRAYAL is a Scrabble word!

Letter values in Scrabble US: P 3, O 1, R 1, T 1, R 1, A 1, Y 4, A 1, L 1.

Is it a valid word?

PORTRAYAL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a word picture of a person's appearance and character
acting the part of a character on stage; dramatically representing the character by speech and action and gesture
a representation by picture or portraiture
any likeness of a person, in any medium
representation by drawing or painting etc

Also: characterization.