The oil and gas rig count, an early indicator of future output, rose 2 to 348 in the week to Dec. 23, energy services firm Baker Hughes Co said in its closely followed report on Wednesday.
The number of operating rigs has surged since August, when it hit a record low of 244, according to Baker Hughes data going back to 1940.
Baker Hughes released its North American rig count report two days earlier than usual due to the Christmas holiday on Friday.
U.S. oil rigs rose to 264 this week, their highest since mid-May, while gas rigs rose to 83, their highest since the end of April, according to Baker Hughes data.
U.S. crude traded around $48 a barrel this week.
Even though the oil contract was down about 22% since the start of the year, it was still up about 170% over the past eight months on hopes global economies and energy demand will return as more governments relax coronavirus lockdowns.
Analysts said those higher oil prices have encouraged several energy firms to drill more.
Looking forward, most energy firms have said they plan to cut spending in 2020 and 2021 as they continue to focus on improving earnings rather than just boosting output.