The Wall Street Journal reported that as the shale boom plateaus and demand for crude oil increases, supply worries are increasing.

According to the Journal, sufficient oil has flowed from America’s shale boom over the past 10 years to allay worries that demand for the world’s most important commodity would outstrip supply. However, the Journal reported, oil prices have risen 15% since the start of 2018 because the shale boom is reaching its limits.