North Dakota, a state at the heart of the U.S. oil boom, reported a modest increase in rig activity for the week, adding two to its state-wide count. On the whole, however, the North American rig count, a key barometer of the health of the exploration and production side of the energy sector, is depressed.

Baker Hughes reports the number of rigs in service in the United States and Canada fell by a total of 23, or 2.2 percent, between April 17 and April 24. Year-on-year, the North American rig count is down by about half.

The price for West Texas Intermediate, the U.S. oil benchmark, fell by about three-quarters of a percent to $59.19. Oil prices remain suppressed, though WTI rallied 25 percent in April.

The low price of crude oil is slowing activity as companies have less capital to spend on exploration and production. Nevertheless, pipeline companies operating in North America said their net income so far is up because capacity is on the rise. Those working in exploration and production, known as the upstream sector, say they're doing more with less as new technologies come on stream.

The international sector, meanwhile, is slowing as well, but at a lesser pace than North America. Baker Hughes reports 1.8 percent fewer rigs internationally week-on-week.

Saudi Arabia, the de facto leader of the Organization of Petroleum Exporting Countries, this week vowed to ensure the resilient Chinese economy had enough oil to meet future demand. Riyadh, meanwhile, broke oil company Saudi Aramco away from the national oil ministry as part of a restructuring plan.

Brent crude oil sold for $66.17 per barrel in early Friday trading, down about eight-tenths of a percent from the previous session. Brent ended April up 20 percent.