Crude oil futures finished lower on 2 April, but witnessed mixed trade for the week, as traders bet that a preliminary deal on Iran's nuclear programme will add to the global supply glut that has hurt oil prices.
Brent May contract finished $2.15, or 3.8%, lower at $54.95 a barrel on Thursday (2 April).
In a holiday shortened week, the global benchmark lost some 2.7% since 27 March.
US May contract finished 95 cents, or 1.9%, lower at $49.14 a barrel on Thursday.
WTI gained some 0.6% since last Friday's close.
Crude oil traders are now worried that Iran's nuclear agreement will pave the way for the easing of sanctions on the Opec member, potentially flooding the markets with Iranian oil.
Thomas Pugh, commodities economist at Capital Economics, told IBTimesUK that a spike in crude supplies could see oil prices drop by as much as $10 or even $20 a barrel in the short-term, although this will likely bounce back soon enough.
Some analysts estimated that the lifting of oil sanctions will result in an addition of around 800,000 barrels a day in global markets but that Iran's return to the oil market would be "long and arduous".
Charles Perry, CEO of energy consulting firm Perry Management told MarketWatch that Iran's oil production has "suffered a long time from the lack of reinvestment of capital into it" and a reinvestment into its oil business has not been enough to "even just maintain, much less expand it".
Meanwhile, Baker Hughes reported that the number of US rigs drilling for oil and gas fell by 20 from last week to 1,028 rigs as of 2 April.
Goldman Sachs oil outlook
On 2 April, a top Goldman Sachs analyst said the responsibility of restoring crude oil prices back to equilibrium lies on nations such as the US and not on oil cartel Opec.
Michele Della Vigna, head of European energy research at Goldman, said the onus lies on non-Opec producing nations because they have created the oversupply in the market, which has hurt prices.
Della Vigna reiterated his call for Brent crude to find an "equilibrium" of $70 a barrel by the end of 2015, but warned that the global benchmark could drop to $40 during the summer months.
The analyst added that a "super spike" to above $100 a barrel was becoming increasingly unlikely and said that $25 for oil was also not a likely scenario.