If something in front of "得"，that's almost is a verb. For example,他变得.....,她走得......, so 经验(experience) right now is a noun, but experience is also sympathize 经历，经历 it could be a verb and a noun, now the sentence says" in his past, he has a lot of experience, and he was experienced a lot. i hope you will understand it. have a good!

他这方面有很多经验。

经历得很多 经验是noun

Thanks so much

This sentence is wrong.You can say 他经验很多or他有很多经验