A drillship participating in a major resource exploration project in the East Sea began its first drilling operation early Friday, the state-run oil company said, marking the full-fledged start of the search for an estimated 3.5 billion to 14 billion barrels of oil and gas.

The announcement followed the arrival of the West Capella, operated by Norway-based Seadrill Ltd., near the southeastern port city of Busan on Dec. 9 for supplies. The drillship reached its first drilling site Tuesday.

The drilling operation is expected to take around 40 to 50 days, with analysis results set to be released in the first half of 2025, according to the Korea National Oil Corp.

"The operation will focus on verifying the presence of oil and gas while setting up strategies for future exploration," KNOC CEO Kim Dong-sub said in a release. "We will spare no effort to complete the drilling operation without disruptions."

The company earlier noted drilling operations generally have a success rate of about 20 percent, meaning at least five sites may need to be explored over several years.

The 228-meter-long West Capella, built by South Korean shipbuilder Samsung Heavy Industries Co. in 2008, boasts a maximum drilling depth of 37,500 feet, or 11.43 kilometers.

The exploration project, however, currently faces challenges as the main opposition-led budget bill passed by the National Assembly slashed the entire 49.7 billion-won ($34.3 million) budget allocated for the 2025 drilling operation. (Yonhap)