Oil output at Kazakhstan's giant Kashagan oilfield fell this month after its operator shut two offshore injection wells on May 20 following the detection of sour gas during routine sampling, the company said on Thursday.
The North Caspian Operating Company (NCOC) closed the wells to conduct an integrity test and further survey program, it said.
"Oil production (was) reduced during this testing period," NCOC told Reuters in an emailed comment.
Kashagan normally produces about 300,000 barrels of oil per day.
Kazakhstan's total daily oil and gas condensate output over May 21-24 averaged 240,525 tonnes per day, down from 252,133 tonnes per day over May 15-20, the country's Oil and Gas Information and Analysis service said.
NCOC is a consortium which includes Shell, Eni, TotalEnergies, and Exxon Mobil Corp, as well as companies from Kazakhstan, China, and Japan.
(Reporting by Reuters; Editing by Jan Harvey)