What are the chances of getting contracted an std when there is no fluid transfer?

Very high: Some infections, like hpv and even herpes only require skin to skin contact. In addition, the inside tissues of mouth, genitals amd anus are all mucosa and thus 'wet' by nature (think saliva). Thus infection risks are still high with penetration even without ejaculation.

Slim: The chances would be slim, but you can still get an std just from skin to skin contact in the genital area.