In my opinion, if you found and started pumping water from an underground aquifer, you didn't homestead the entire aquifer but only the daily flow of water which you extract from it. However I think when you find a natural gas field (http://en.wikipedia.org/wiki/Natural_gas_field) at the sea, you homestead the entire field. Although both of these natural resources are underground treasures, I think homesteading rules should be different for them. That's because it takes huge amount of money and efforts to find a natural gas field, whereas aquifers are a lot easier to find. In addition, water is a basic thing that humans need in order to survive, whereas gas is not. What do you think?
It is the cost of resource extraction that prevents others from homesteading the same natural resources. And that is a good thing. Homesteading is base upon using the property exclusively and to have homesteading rights over an entire aquifer that person would have to use the entire aquifer and make the ability of others to use it prohibitively expensive. When you homestead a property by placing a well or other extraction device accessing a natural resource then you do not homestead the entire natural resource and you may have others homesteading the same resource. This is also true for the natural gas well out in the ocean. So absent any societal conventions the only economic difference is the difficulty/cost of accessing and taking advantage of the resource. I understand that there could be societal conventions and some of these conventions may/will treat natural gas differently than they treat clean water and those differences would be up to arbitration to determine which are valid and which are not.
Not exactly. There is more to homesteading than just getting some thing out of the ground. A homesteader would have to have the equipment to get the gas, install the equipment and have the pipelines to move it. Neither of those are free and you would need to cross the property of others who may/will require payment for your tresspass. But most importanly, the homesteader, or anybody else, would need a customer to pay for the end product.