A recent report from research firm IHS Markit said drilling in Permian Basin must accelerate to maintain current production volumes. According to the Houston Chronicle, the report said shale wells deplete faster that conventional vertical wells so more drilling is required to maintain higher production. Because drilling activity is declining in Permian Basin – and elsewhere – IHS Markit said U.S. crude oil production will experience moderate growth in 2020 and flatten in 2021. Production volumes from existing wells fell by 34 percent in 2018 and by up to 40 percent in 2019. U.S. Department of Energy said production in Permian Basin started 2019 at 3.8 million b/d and reached 4.7 million b/d in December.