This topic was discussed extensively on the old Bad astronomy forum. Don't know if it is still archived. It might be worth rereading if you are interested and it is available.

Just some points raised in this discussion.

Oil is derived from three types of organic matter - cyanobacteria, plankton (especially phytonplankton), and land plants. each as its specific chemical signature.

I haven't heard about dry wells reflowing but it could occur several ways. Overpumping might do it, just as with water. Also improvments in extraction technology may make it possible to extract oil from formerly abandoned wells.

There is very little evidence in favour of Gold's hypothesis, and lot's against it.

Jon