The phrase "barely studied" is correct and can be used in written English.
It means that someone or something was not studied thoroughly or extensively. Example: Despite spending hours in the library, she barely studied for her exam and ended up failing.
They were barely studied, microbiologists explained, because it was hard to know much about them.
As a result, some hearing lawyers have never spoken to the client, and have barely studied the file.
Finishing soon afterward was Gerard Waterman, a towering Little League coach, who bragged that he had barely studied.
That boundary and the territory it defines is wide: abstract painting by African-American artists is a rich and barely studied aspect of 20th-century American art history.
Having barely studied the period, I hadn't realized that twelfth-century nobles favored the rhetoric of a miked-up Tony Robbins.
In college, I would approach every exam, even those I had barely studied for, with the thought that I was going to do well.
"I'd only started reading music at 15, and couldn't really sight-read, so I could barely study anything".
His petulant roommate, Barney, who is obsessed with getting into an elite college, comments bitterly on the injustice: "I study all the time and all I ever get is B minuses, and you barely study and smoke pot all the time and get all A's".
The general academic education (HAVO) was so easy; I got all my exams by barely studying".
"I'm sure you know this already, but though Aki-kun's in his second year of cramming for the entrance exams, he barely studies.
Quickly, responders within the Unified Command embraced the idea, even though its implications had barely been studied.
