The majority of 'subsidies' given to the oil and natural gas industry are not actually subsidies in any real sense. Most of the 'studies' that like to report such enormous world wide subsides inflate their figures by defining a subsidy in such a way that even if when gas companies themselves don't get any money out of it it's added to their totals.
For instance the top 3 'subsidies' in the US, making up half +/- a few percentage points every year are, the strategic oil reserve, farm fuel tax credit and the various low income home heating credits.
The first is, as the name implies, a strategic reserve of oil that the US government keeps on hand to act as both a security blanket if anything bad happens to the oil supply or at times a tool to help control pricing if they believe their is not enough supply to meet normal demand.
The farm credit is simply the amount of money farmers don't have to pay torwards normal road taxes on fuel for equipment that does not run on roads.
The home heating credits are just that, credits given to low income people in colder climates to ensure they can heat their homes during winter.
None of those really go into the pockets of the oil companies but they are all counted towards the 'subsidy' totals reported. Similar programs exist in many other countries and help greatly inflate the global subsidy numbers.
Even regular business expenses are often deemed subsidies for the purpose of these reports. For example, say the normal practice allows for depreciation of an asset over some fixed period of time like 5 years. If an oil company requests the ability to depreciate that asset over an 8 year timespan instead and someone writes an exemption for them then all the tax savings from their ability to depreciate that asset are generally included in the 'subsidy' total. Never mind that all companies do that and it's not usually considered anything special, but when you're trying to make numbers as big as possible anything with the word oil or gas on it counts.
That's not to say they don't get direct subsidies too, they do, but the real numbers are just a fraction of the numbers used by most of the studies about ff subsidies.