As for Yemen, it has proven oil reserves of about 4 billion barrels which corresponds to about 10% of the US proven oil reserves. https://en.wikipedia.org/wiki/Economy_of_Yemen
Here is a detailed USGS analysis of Yemen oil reserves with detailed geological background information. The report states that Yemen oil reserves could be as high as 9.8 BBOI, or about 25% of US proven oil reserves for a country that has about 9% of the US population.
Other reports claim that Yemen's has even greater oil reserves bordering on Saudi Arabia.
[...]That's all regarding Yemeni oil that's mentioned in the comment. But regarding the report posted at Facebook linked to in the comment, I've never heard of a "U.S. Sky News station;" my guess would be they pick up news reports from Britain's Sky News, which I wouldn't consider the most reliable source. But for what it's worth, here are quotes from the report posted at Facebook -- which if anywhere near the truth would be pretty astounding and put the Yemen War in a new light. Caveat: some of the English in the report is a little garbled. In any case, there is considerable oil in Yemen. The question, raised by the report at Facebook, would be how considerable.
Revealed "Sky News" to station US television, the largest source of oil in the world up to oil reserves underground is in Yemen, and extends sections of it to Saudi Arabia at a fraction at a depth of 1800 meters, in a border area called Al-Jawf, but that vast reservoir is under the land of Yemen and is the first in the world, in terms of inventory, whether Saudi Arabia has 34% of the world's oil reserves, the discovery of these wells of oil in Yemen makes Yemen owns 34% of the extra global stocks.
A writer Charles Ayoub in his article published newspaper "home" of Lebanon seems to be the war that took place in Yemen and was the United States and Saudi Arabia is a party, it was about oil wells where it remained negotiations for two years, and the previous government of Yemen want to enter Russian companies to British companies and American side. But the dispute has been obtained to prevent the announcement of this new discovery in Yemen are being asked the question what is the future of Yemen at the moment ??
Because it will become richer than Saudi Arabia, but the richest country in the region and the way how to control this vast reservoir in the world, which has become is the first in the world, while the Yemeni regime is stable, despite the dominance of America on the reins of power in Yemen before and after the dimensions of President Ali Abdullah Saleh, and then keep his brother from the leadership of the army, and the dimensions of the children of his brothers for the leadership of the air, armor and Navy.
According to rumors, unconfirmed, that Saudi Arabia offered to Yemen, to pay her an annual $ 10 billion, compared to give it a privilege of extracting oil from Yemen 50 years, but that Yemen did not approve.
Also, US companies and French offered lucrative offers, but the essential problem is that the wells zones located in Al-Jawf regions and Marib, which the Americans and Saudi Arabia is trying to control them through the laying-Qaeda elements who speak Baadaiathm those who are called Houthis, who are the children of the indigenous region who reported that the Iran-backed exchange for support for Saudi Arabia America for those elements therefore struggle for energy in the next 20 years may be a great energy on Yemen, and the conflict between Moscow and Washington on oil investment in Yemen.