U.S. shale oil producers are braking for drilling activity recently as oil prices fall and concerns about growing oversupply.

Centennial Resources Development, a shale oil producer, recently cancelled its in-use rigs in conjunction with its rivals Diamondback Energy and Parsley Energy. Centennial Resources Development cancelled its production target for 2020 and plans to increase two rigs on the grounds of weak market.

John Robbie, chief executive of Teal Natural Resources, an oil producer, said the drop in oil prices was shocking. Many shale oil producers are cutting new development projects and drilling rigs in use.