This summer the U.S. oil price has whipsawed from more than $50 a barrel in June to below $40 earlier this month. In the past two weeks it has risen more than 20%, to a recent $48.22 a barrel.

Prices have struggled to go much higher than $50 a barrel. After the longest run of gains since March, Brent crude, the international benchmark, traded 0.9 percent higher at $51.17 at 7:13 a.m. in London on Friday.

International Brent crude oil futures were trading at $46.20 per barrel at 8.47 p.m. ET, up 16 cents, or 0.35 percent, from their last close and not far off their $46.30 monthly high reached in the previous session. U.S. West Texas Intermediate (WTI) crude futures were at $43.71 a barrel, up 22 cents, or 0.51 percent, from their last close.

However, in conjunction with both lower oil prices and international sanctions, Russia has recently experienced five consecutive quarters of decline in GDP, representing that country's deepest economic downturn since 2008-09.

Brent crude LCOc1 was up 27 cents a barrel at $42.07 at 0957 GMT (0557 EDT). It reached $41.51 on Tuesday, the lowest since April 18. U.S. crude CLc1 added 28 cents to $39.79.

Russian assets are under pressure as concerns resurface that the global oil market is over supplied. After rallying from a record low at the start of the year as crude rebounded, the ruble is the third-worst performer in emerging markets so far this quarter.

Международное рейтинговое агентство Moody's ухудшило свой прогноз по цене нефти марки Brent в 2016 году до 43 долларов за баррель с ожидавшихся ранее 53 долларов за баррель в связи с тем, что высокий уровень добычи нефти значительно превысил рост ее потребления.

Crude oil prices bounced back on Wednesday from steep falls in the previous session as strong Japanese economic growth surprised markets and the business outlook in Australia also seemed to brighten, stoking producer hopes of increased demand.

North Sea Brent crude oil prices averaged $60/barrel (b) in April, a $4/b increase from March and the highest monthly average of 2015. Despite increasing global inventories, several factors contributed to higher prices in April, including indications of higher global oil demand growth, expectations for declining U.S. tight oil production in the coming months, and the growing risk of unplanned supply outages in the Middle East and North Africa.

Eni SPA reported a first-quarter consolidated adjusted operating profit of €1.57 billion, down 55% from first-quarter 2014. The company says the decline was driven by lower crude oil prices, and only partly offset by a better performance recorded in upstream activity and in all other business segments.