North Caspian Operating Co. said there were minor leaks and other technical difficulties that caused operations to cease twice in September and investigators were looking into what caused the problems, the Platts energy news service reported.
"Oil and gas production remains [closed] until the results of the expert studies are available and restart of the facilities can be carried out safely," the company said.
Kashagan is one of the largest oil fields in the world, with an estimated 16 billion barrels of oil reserves.
Platts reports the field is expected to reach an average production rate of 160,000 barrels per day next year despite the late 2013 complications.
North Caspian serves as the operator of Kashagan, representing a consortium that includes ConocoPhillips, Exxon Mobil, French energy company Total, national energy company KazMunayGas, Royal Dutch Shell and the Japanese oil company Inpex.