Kim Dong-sub, the head of Korea National Oil Corp., speaks during a briefing held in the central city of Sejong in this file photo taken on June 19. (Newsis)

South Korea's state-run oil developer has selected US-based Schlumberger as a service provider to analyze the rock and gas composition of a potential gas field in the East Sea, a document showed Sunday.

Schlumberger will conduct the "mud logging" operation for an excavation project in the East Sea that could potentially uncover between 3.5 billion and 14 billion barrels of gas and oil, according to Rep. Kim Won-i of the main opposition Democratic Party, who cited data from Korea National Oil Corp.

If confirmed, the quantity would be sufficient to meet the country's gas demand for up to 29 years and its oil demand for four years.

A mud logging operation focuses on evaluating geological formations by measuring and analyzing the quantity and composition of gas present in the drilling mud extracted from potential sites.

Schlumberger plans to secure the necessary geological data through measures including hydrocarbon testing and gas composition analysis.

The country aims to carry out the first drilling operation in December.

The state-run oil company earlier said it has found seven potential locations for oil and gas reserves, with an estimated success rate of around 20 percent, meaning 1 out of every 5 holes drilled would be successful.

Costs, meanwhile, have been one of the major hurdles for the development project, as drilling a single hole is estimated to cost around 100 billion won ($73 million) to 130 billion won. (Yonhap)