Collude, Obama is not competent enough, synchronicity maybe. Probably the Saudis were contemplating having a go at US oil but once they realised it was hurting the "Axis of Wackers" such as Iran, Venezuela and Isis it is more likely they just kept going. In the US oil growth is in spite of Obama, if he really wanted to do this he would OK the Keystone pipeline.

I think the price drop was due to a lack of storage space for temporarily excess oil production. When that eases the price could go the other way. One thing is more certain, namely that the total number of barrels will one day go into permanent and irreversible decline. Econ 101 says reduced supply means higher prices but maybe that doesn't apply to oil. The International Energy Agency says world liquid fuel production (including tar sands and biofuels) has a way to go yet from 98 million barrels a day to 130 mbpd or similar. Some say we'll peak at 100. It would be nice if it stayed cheap until the end. Not sure what happens then.

Why would the US collude in cutting its own throat ?
I am amazed that this article is from Oil Price .com.

The present oil price means the end of the tight oil production.
Drilling lease approvals have collapsed, as contracts run out so will
the tight oil production.
The collapse of tight oil production will reveal, the small as yet,
decline in conventional oil which peaked in 2005.

Saudi Arabia will not shed tears over the tight oil collapse, but to
have the US involved means that there is madness in the US government.

The US's "recovery" has been based on its reduction of oil imports
from about 11 million barrels a day to 8mbd.
That is a big save on import expenses. $300,000,000 a day !

Russia, Iran and Venezuela all find themselves in the cross-hairs. As the US continues to be squeezed out of Central Asia, that's where they will remain - Russia and Iran because they are key players in Central Asia, and Venezuela because she has had the temerity to challenge the Yankee overlord-ship of South America.
Syria is important mainly because she is supported by Russia and Iran, and because Israel wants her neutered.
As the US's Empire of Chaos begins to crumble, and as China emerges as a global alternative, the US tries to encircle both China and Russia via the "pivot to Asia" on the one hand and support for the Nazis in Ukraine and the jihadists in the Middle East on the other.
Shoot-from-the-hip sanctions (witness the recent move on North Korea for unsubstantiated hacking of Sony) continue to undermine the US's credibility. The sanction-led attacks on Russia and Iran have had the perverse effect of lowering the price of energy and thereby making the global emergence of China even easier.
Of course there has been collusion. The end of the petrodollar is imminent. A new global economic order is emerging, and so far no effective plan to challenge what is emerging as an historical shift has emerged. The powers that be within the Beltway are packing it. So is the House of Saud.

I just don't see any US or Saudi collusion. Just the Saudis reacting to protect their market share!
Nothing more, nothing less!
Rhrosty.

Few things more succinctly demonstrate the difference between US rhetoric and reality than their support for the corrupt autocracy that is Saudi Arabia. Ever since Kissinger negotiated the (then secret) deal in 1972 that all oil sales would be denominated in $US thereby propping up the US to this day, the two nations have been as thick as the proverbial thieves. Only the terminally naive will not accept that the September 2014 meeting referred to in the article was other than part of the geopolitical ploys that the Americans are making.

An oil price of less than $US80 per barrel renders the shale oil industry uneconomic. Several firms have already collapsed. Obama and his advisers must have calculated this effect of depressing oil prices, but clearly decided that it was a price worth paying to further squeeze the Russians. This strategy will fail. One reason is that the net price in roubles paid to the Russians is virtually unchanged, the depreciation of the rouble being offset by getting more roubles for each dollar denominated barrel of oil.

A second reason is that Russia is demanding payment for its oil from western nations to be in gold. The ramifications of this were not mentioned by the author. Neither did he (or indeed the Oz press) mention the fact that China's Foreign Minister effectively underwrote the Russian economy by guaranteeing Chinese support through the present difficulties. That is consistent with a wide range of joint infrastructure projects the two countries are undertaking, not only bilaterally, but within the context of BRICS, the SCO, the Eurasian Free Trade Zone that came into effect on 1 January 2015, and other developments that the majority of the Australian public are blissfully unaware of because of the abysmal level of journalism in the msm.