stand is the intransitive verb, and the parts are: stand, stood, stood
He stood in the hall and shouted my name.
If you replace stand by be, you can see how /petrified/ works.
He was petrified.
That is a passive verb formed by be + past participle. And (here's the crucial point), the past participle in English can be used as an adjective. Also, it can be viewed as an adjective to describe the state of he. One can replace an intransitive verb here with the verb be to show that it is intransitive.
In any event for me this can be seen two ways:
1) Adverbially, as it describes how he stood.
2) Adjectivally, as through transformation (the one I did perhaps imperfectly above), one can see it is an adjective and thus can be modifying the I.
Often, one can go at grammar in more than one way. And in some cases, more than one structure can be shown to exist.