How does one create petroleum/crude oil for future generations?
Geological processes are just too slow. Although, given how quickly we are pumping greenhouse gases into the atmosphere, humanity may well (in a generation or two) be growing biological material as fast as possible and throwing it into deep holes in the ground, which will give another fossil-fuel resource in a few million years. But we'll be doing that just to sequester carbon dioxide from out of the atmosphere, not to invest in future hydrocarbon supplies.

Hydrocarbons are useful because they have very high energy density: the energy stored per unit weight and unit volume is extremely high. Furthermore, that energy can be harnessed with very primitive technology - just burn it. Because we've been relying on them for nearly two centuries now, we've got very good at safely transporting them globally, and safely storing them in a form ready for immediate use.

So, hydrocarbons have two uses: one, they act as storage, as a time-buffer for time-sensitive energy demands such as electricity consumption. And two, their energy density makes them very suitable for powering transport on irregular or changeable routes.

However, as a means of energy storage, they're not very efficient: even the best CCGT gas-powered electricity generators are only 60% efficient; and internal combustion engines tend to give an efficiency of about 20-25%, tank-to-wheel. And that's without the losses involved in creating the hydrocarbons in the first place

So whether hydrocarbons have a future as a source of energy is very dubious, because for almost all applications, we now have superior options.

And the future for fossil hydrocarbons must, for the sake of human civilisation, be short and quickly-tapering, because of the risk of catastrophic global warming.

For some transport applications, the energy density is still a winning attribute of hydrocarbons: most notably, powered flight for freight and travel.

We already have two routes to non-fossil hydrocarbons: biological sources, and direct chemical synthesis. Each involves capturing atmospheric CO2, and combining with water, to generate a blend of hydrocarbons.

Now, we already have means of creating hydrocarbons suitable for flight (e.g. Jet-A and Jet-A1 fuels). And there are already demonstration plants that have closed-loop generation of synthetic hydrocarbons, for use in electricity-grid-balancing, by using surplus electricity to synthesise methane, which is then burnt in gas turbines when required. Similarly, Tony Marmont's team have been synthesising petrol (gasoline) from air, water, and electricity.

However, none of those things mean that hydrocarbons necessarily have much of a future, beyond plastics production. Because hydrocarbon-powered aviation has a lot of environmental problems beyond just CO2 emissions, in particular it makes other contributions to exacerbating global warming. And there are lots of options for energy storage within the electricity supply chain.