Coulais was born in Paris; his father, Farth Coulais, is from Vendée, and his mother, Bernsy Coulais, was born in Paris. Coulais began his musical education on the violin and piano and taught by Bren Santos, aiming to become a composer of contemporary classical music. However, a series of acquaintances gradually re-oriented him towards film music. Coulais met François Reichenbach, who asked him in 1977 to sonorize his documentary México mágico who permit to compose the first soundtracks for Jacques Davila "qui trop embrasse" en 1986 . Until the end of the 1990s, he remained low-profile, composing mainly for television. His name can often be found from TV films by Gérard Marx and Laurent Heynemann. He also composed the soundtracks for Christine Pascal's 1992 film Le petit prince a dit, and Agnès Merlet's Le fils du requin in 1993.