TL:DR We got more than enough oil to last us until we figure out how to suck energy out of the sun.
Most of the oil reserves are dead forests, dried up lakes and massive fungi that covered the landscape (fun fact, the largest living organism is a mushroom that's a bit shy of 2400 acres). They get buried and over time then heat and pressure turn them to oil.
It's possible to synthesize oil but it's generally not worth the energy to do it. It basically shows the same process, but very quickly.
Abiotic oil is currently just a theory, but all life is made of carbon and you can't have life before carbon, so... it makes sense that non-organic oil exists, or can exist.
If abiotic oil is proven to be incorrect, then oil is finite and we will run out in time. Once again, we can make wood oil if all else fails but it's estimated that we've only used 30% of all oil resources known to man. The problem is that you can't suck oil out of the ground, it has to be pushed out. This means that once an oil well is out of pressure (usually natural gas that's dissolved into the oil, the same way C02 is dissolved into a soft drink) the oil is stuck. There's a method of extraction where you can collect the natural gas that comes out of a well and pump it back underground to keep the oil well at a relatively stable pressure. This allows you to collect about 70% of what's in a well, instead of the 20-30% depending on how the well was drilled and maintained. Taking the same process further, you could then pump water into the ground, the water will repressurize the well, just like the natural gas, but the oil will also float to the top. The issue with that however is that water is far more valuable than oil, we just... take it for granted. Salt water can be used, but salt water fucks with machinery really bad.
While Solar power is kinda hippy bullshit, it has the most potential and people are actively working on it. It's estimated that the sun puts out approximately 4,000,000 tons of energy per second. The world consumes about 97 million barrels per day (about 14,550,000 tons). If we could create a dyson sphere around the sun, it would take less than 4 seconds to fuel the entire planet for the rest of the day. There are many problems with solar but the most basic is that it requires oil to gather and combine materials to make them. It takes approximately 7 years for the average solar panel to become carbon neutral. Another major issue with solar power is that you need batteries to store it, since... surprise surprise, once the sun goes down, your power is out. Batteries of course take more oil to gather and combine materials.
Minor correction.
Fossil fuels. Dead plants etc. under lakes produces coal.
It takes shallow oceans to produce oil.
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