Reverse engineering of metal detector

Hey guys

I need some help I, I am working on this metal detector basically I am reverse engineering it. It is based on the principle of pulse induction. I have posted a picture of part of schematic which I have reverse engineered. I want tips on how I can understand this op-amp functions here or is there anyway to solve, what steps should I take. I have got metal detector books and stuff but here many things are different in the book it was way to simple.

help will be appreciated