The price of oil could be stuck firmly at around $50 a barrel by 2020, a Goldman Sachs analyst told CNBC, raising new fears about the energy companies that have already started to cut costs, projects and jobs to cope with falling revenues.
Several big oil and gas companies announced this week they intend to make cutbacks to stay afloat in this sinking environment. Royal Dutch Shell expects to cut 6,500 jobs, 6,000 for Centrica, and at Chevron, a 2 percent slash to its global workforce.
These measures were introduced while Brent crude and West Texas Intermediate (WTI) crude are trading around $53 and $48 a barrel respectively as the Organization of Petroleum Exporting Countries has kept its supply high – and process low – in its battle for market dominance over U.S. shale oil.
Read MoreChevron earnings miss expectations
But Michele Della Vigna, co-head of European equity research at Goldman Sachs, told CNBC Friday that by 2020, they see oil around $50 per barrel.
"What we've learned from this reporting season is that deflation is accelerating from a cost perspective. Efficiency is improving in all the mature regions and productivity is sharply improving in almost all the shale places in the U.S."
"With all of that compounds to what we think will be a multi (year) deflationary trend in oil. If we look to the end of the decade, we see oil at $50, as this productivity continues and as costs keep coming down."
Goldman Sachs' estimate conflicts with World Bank's latest commodity price forecast, who forecast crude oil to be at $57.50 per barrel on average this year, and $71.90 by 2020.
A time to buy?
However, this isn't a time to get despondent. Roberto Cominotto, Investment Manager at GAM said in a note, that the energy sector still can provide attractive investment opportunities, despite the low oil price environment.
"The energy sector (still) provides attractive investment opportunities, even with oil prices significantly below 100 USD. These can be found primarily in mid and small cap producers, which have the lowest production costs in the sector."
Cominotto gave U.S. shale oil and gas producers as an example, like Cardinal Energy or Torc Oil & Gas as these firms can grow even at this current level.
Todd Horwitz, author & founder at Averagejoeoptions.com, also seemed optimistic on the energy sector, telling CNBC Friday, that he would put money on the sector, during its most "stressed times."
"We know that oil can go a bit lower, that's there's trouble with the dollar, there's worldwide manipulation with the currencies, but here's a level – you've got stocks like Haliburton down around 40 – you've got a lot of good opportunity here, that if you're investing these are opportunities to buy into these markets because these companies are strong and will improve with stronger prices."
Read MoreWhyUS oil will never go it alone
Outlook for shale?
In terms of U.S. shale, Vigna gave its current breakeven at $60 per barrel, however it expected it would eventually match up with other oil prices at $50 per barrel by 2020.
"(For shale,) it's not just about becoming more efficient and costs coming down, it's about improving the technology."
"As we improve productivity, and each well starts to produce more and recover more from the ground, this is where we think will lead to this longer-term coming down of the oil price required for shale production."
"At the moment, we think the breakeven is around $60, and is going to come down around $50 by the end of the decade."
He added that the cuts in capital expenditure are currently happening in areas "higher on the cost curve", including deepwater, heavy oil and temporarily in shales. He went on to say this will result in services costs reducing and countries become more competitive, fuelling this "deflationary spiral."