You can be a non traditional student in geology, but most universities require a few courses. These probably include:
Physical Geology, Historical Geology, Sedimentology and Strat, Structural Geology, Petrology, and Mineralogy. Pretty much all grad schools require Field Camp, but some will accept you and let you make it up while you are there or the summer before you start. You could also probably take 1/2 of these mentioned above, but these are all pretty much required for field camp anyway.
Geology programs also typically require 2 semesters of calculus, 2 semesters of calculus based physics, and 2 semesters of chemistry, but if you are a non traditional science major you probably have these anyway.
Mamba 558 I would set my sights a little lower those programs are really hard to get into. You don't really need to go to a top program to get into the mining or petroleum industry, unless you want to work for a really prestigious company. I would recommend going back to undergrad for a couple years (1-2), then applying to some less prestigious schools.
Also if you are interested in the outdoor aspects of these fields, you could probably get a job now after taking a couple of undergrad classes (and maybe even with the experience you have). I worked as a geologist in a mine for an internship with 0 economic geology experience. You also might be able to get a job as a mud logger in the petroleum industry (most of the training is on the job anyway). There are also a lot of environmental consulting firms (at least in Arizona) that hire geologists straight out of undergrad for entry level positions in field work positions. These careers probably don't pay what you are used to ($35,000-$45,000) but they are entry level. Also the hours probably suck. But there is a lot of outdoor work involved in that is what you are interested. You probably won't get to see the world but you will get to see the USA.