U.S. oil producers overall have been reluctant to ramp up output even as crude prices climb and demand rebounds. They have focused on generating cash flow and exercised patience as the economy recovers from the pandemic.

But shortages of supplies needed for drilling and resulting inflation amid coronavirus fallout could extend the trend and keep production in check into 2022. Citigroup Inc. analysts said in a June report that inflation could eclipse 12% in the North American oil and gas sector by the end of 2021, driven up by rising costs for everything from steel to cement.

Oil prices recovered from last year’s pandemic-induced slump and have climbed about 40% this year, enticing global producers to ramp back up in recent months. But the Citigroup team said oilfield services...