Mostly it becomes water and CO2, which is typically trapped with the oil. But don't measure by mass, just number of atoms forming different molecules. Two hydrogen have far less mass than oxygen but still form the most stable bond. With the heat and pressure, the long chain hydrocarbon molecules oxides, until no free oxygen is left.
@thackney Far more CO
2 than water. Here's the stoichiometry. It maximizes HC output and assumes a C-H hydrocarbon ratio of 4:9, the same as 3-methyl heptane (or octane)
From p. 262: C = 106, H = 177.1, O = 59
Output: C-H → [C = 77.3, H = 173.9], CO
2 = 28.7, H
2O = 3.2 - (a ratio of 3 moles CO
2 per one mole C
8H
18)
This is definitely doable with the algae composition provided. But the next question is where did all the CO
2 go? Wouldn't one expect all that CO2 would end up at the same place as CH
4?
We are in a gas-poor field, yet we bring up more than enough to run our generators and push the remainder into the pipeline. If it was CO
2-rich, the generators wouldn't run.
And finally, if all this algae and phytoplankton piled up on the ocean floor, then why are there no such deposits existing today? Think of the Gulf floor now. How is it possible that hundreds or thousands of feet of phytoplankton was able to pile up on the ocean floor, and then was covered with sandstone formations without releasing any of its carbon content (or oxygen content for that matter since it was needed to bind the carbon in place). And eventually, enough rock was built on top of the organic matter to 'cook' it into oil, releasing all its oxygen in the form of CO
2, and then somehow the CO
2 was able to escape through the rock layer leaving methane trapped behind. And this only happened in select parts of the world.
Sorry, I just find that hard to swallow. I find it much more likely that the earth was bombarded by meteors and comets that were hydrocarbon rich.