International Brent crude oil futures LCOc1 were at $76.14 per barrel at 0625 GMT, down 7 cents from their last close.
U.S. West Texas Intermediate (WTI) crude futures CLc1 were down 11 cents at $68.76 per barrel.
Traders said markets were range-bound, hemmed in by conflicting price signals.
The monitoring committee of the Organization of the Petroleum Exporting Countries (OPEC) found that oil producers participating in a supply-reduction agreement, which includes non-OPEC member Russia, cut output in July by 9 percent more than called for.
The findings for last month compare with a compliance level of 120 percent for June and 147 percent for May, meaning participants have been steadily increasing production.
OPEC and its allies agreed in late 2016 to cut output from 2017 by around 1.8 million barrels per day (bpd) versus October 2016 levels.
ANZ bank said on Monday that investors were “expecting (U.S.) inventories to rise this week” as some refineries go into maintenance.
Weekly inventory data will be published by the private American Petroleum Institute (API) later on Tuesday.
Official data is due on Wednesday from the U.S. Energy Information Administration (EIA).
Meanwhile, the International Energy Agency (IEA) on Monday warned of further supply disruptions, especially from Venezuela, where an economic crisis has cut deep into the OPEC-member’s oil output.
Venezuelan crude oil exports had halved in the previous two years to just 1 million bpd by mid-2018, according to trade flow data.
“We can expect a further fall,” the IEA’s Executive Director Fatih Birol told Reuters in Norway on Monday.
Birol also warned that African OPEC-members Libya and Nigeria “seem both still fragile countries” despite some recent improvements.
Birol said it was too early to gauge the impact of the U.S. sanctions that will target Iran from November.
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