There are oceans of liquid hydrocarbons on the moons of Jupiter.
Yeah liquid ethane, methane and traces of propane all linear alkanes and all only liquid at the very low temperature of deep space. The “oceans” are not complex aphanitic or cyclic hydrocarbons such as crude oil. Which has well over 200 different hydrocarbons with ring, branches, and isomers. Methane can be synthesized from CO2 and H2 in the presence of Fe,Ni or Cu with pressure ethane and propane as well. The conditions in the outer solar system where it is cold enough to not lose the H2 that was present at the formation of the solar system along with the CO2 the natural form of carbon in the universe as it is fully oxidized and has the lowest Gibbs energy levels. Titan Saturn’s moon has liquid oceans of methane and it rains ethane here again from solar nebula H2 and CO2 from 5+ billion years ago when the sun and planets coalesced from the stellar nebula. Earth is too close to the sun to have held on to its initial H2 atmosphere all of that was stripped away via solar wind billions of years ago. H2 is too reactive to exist in the mantel or crust it would be reacted with any electron donor oxygen being it’s Gibbs low point , but sulfur, carbon, nitrogen all have electron affinity for hydrogen. There is a reason you cannot drill a well and find hydrogen gas it very VERY rare it takes reducing conditions underground and high temperature under HUGE pressures. Most of the earth hydrogen is bound in water that is itself bound to hydrated minerals in the mantel of the earth enough to fill the oceans hundreds of times over but it’s chemically bound for all eternity to solid rock well semisolid as the mantel flows.