I'm not sure if data from the analysis will be made available to the large public anytime soon, but in the links below you can find more information about the protocol in use, measures taken so far and a statement from Petrobrás about the type of oil found in the region.
English tl;dr: Gas Chromatography and “Positive Ion Electron Impact Low Resolution Mass Spectrometry” allow them to compare the samples with known samples from other oil fields. Since petroleum has organic origins, it’s footprint is pretty much specific to the environment it comes from.
https://g1.globo.com/economia/noticia/2019/10/25/petrobras-d...
https://www.marinha.mil.br/manchasdeoleo/informacoes-sobre-o...
http://www.petrobras.com.br/fatos-e-dados/recolhemos-mais-de...