Brent crude futures were down 8 cents, or 0.2 percent, at $51.41 per barrel at 0651 GMT. U.S. West Texas Intermediate (WTI) crude futures were down 10 cents, or 0.2 percent, at $48.94 per barrel.

Brent crude futures LCOc1 rose 30 cents to $50.50 a barrel by 0959 GMT, after rallying more than 3 percent on Tuesday. U.S. West Texas Intermediate futures CLc1 climbed 40 cents to $48.29 a barrel.

Brent September crude futures fell 18 cents on the day to $47.88 a barrel by 0850 GMT. The price fell 2.5 percent on Friday after a consultancy forecast a rise in OPEC production for July. NYMEX crude for September delivery fell 20 cents to $45.57 a barrel.

International benchmark Brent crude futures were at $49.28 per barrel 0501 GMT, down 2 cents from their last close. U.S. West Texas Intermediate (WTI) crude futures were at $46.89 per barrel, down 3 cents.

Brent crude futures LCOc1, the international benchmark, were up 11 cents at $48.95 per barrel at 0925 GMT. U.S. West Texas Intermediate crude futures CLc1 were at $46.50 per barrel, up 10 cents.

Brent crude futures were at $49.02 per barrel at 0656 GMT, up 11 cents, or 0.2 percent, from their last close. U.S. West Texas Intermediate (WTI) crude futures were at $46.64 per barrel, up 10 cents, or 0.2 percent.

Brent crude futures LCOc1, the international benchmark for oil prices, were down 7 cents, or 0.1 percent, at $48.35 per barrel at 0443 GMT (12:43 a.m. ET), but up 3.5 percent for the week. U.S. West Texas Intermediate (WTI) crude futures CLc1 were at $45.97 per barrel, down 11 cents, or 0.2 percent, but up around 4 percent over the week.

Oil prices rose more than 1 percent on Wednesday, extending gains from the previous day as the U.S. government cut its crude production outlook for next year and as fuel inventories plunged. Brent crude futures were up 60 cents, or 1.3 percent, at $48.12 per barrel by 0657 GMT, while U.S. West Texas Intermediate (WTI) crude futures were at $45.72 per barrel, up 68 cents, or 1.5 percent.

Brent crude oil prices are forecast to average $51/b in 2017 and $52/b in 2018. Average West Texas Intermediate (WTI) crude oil prices are forecast to be $2/b lower than the Brent price in both 2017 and 2018. Henry Hub natural gas spot prices are forecast to average $3.10 per million British thermal units (MMBtu) in 2017 and $3.40/MMBtu in 2018.

Because two major crude oil price benchmarks, West Texas Intermediate (WTI) and Brent, account for 70% of the weighting in the S&P GSCI energy index, the energy index tends to follow major price movements in the crude oil market. During the first half of 2017, WTI crude oil prices declined by 12%, while Brent prices fell 14%.