More crude is leaking at an oilfield in the Bohai Sea in northeastern China where a major spill occurred last year.

In the latest incident, ConocoPhillips China said 0.6 tons of crude oil were spilled on June 3 at the Penglai 19-3 field. ConocoPhillips China and China National Offshore Oil Corp. (CNOOC) own the oilfield.

The latest spill occurred at a different platform than the two that leaked last year.

CNOOC released a statement on June 4 that said it received a report from rig operator ConocoPhillips, which said that a safety device on a valve on the main pipe failed.

ConocoPhillips also told CNOOC that it cleaned up the oil slick immediately after it was discovered. An inspection by CNOOC showed that as of 3 p.m. on June 4, no oil was seen on the water, CNOOC said. CNOOC said it would coordinate with the ConocoPhillips to clean up any more oil that might appear.

In July 2011, the central government ordered the two companies to halt production at two platforms in the Penglai 19-3 oilfield due to an oil spill. The first leak appeared on June 4 at the site's B platform, and the second was on June 17 at the C platform.

ConocoPhillips China said 700 barrels of crude leaked into the Bohai Sea, and 2,500 barrels of mineral oil and oil-based slurry sank to sea floor between early June and late August.

The State Oceanic Administration (SOA) said the spills at two rigs polluted more than 5,500 square kilometers, affecting roughly 7 percent of the Bohai Sea.

The government and the oil companies were heavily criticized for their handling of the accident. The SOA held its first press conference about the oil spill on July 5, a month after the first leak started.

The next day ConocoPhillips China officials addressed reporters for the first time.

At that press conference, company officials said the leaks at the two platforms had been sealed, and that the mess had mostly been cleaned up.

However, on July 10, several reporters traveled to the area in chartered boats and saw oil oozing into the ocean. The SOA confirmed that day that the leak continued.

On August 31, ConocoPhillips said it met an SOA deadline for sealing off the sources of the spill and had taken steps to prevent future leaks.

CNOOC, which holds a 51 percent stake in the oil field, kept out of the public view during the episode. While the SOA has officially blamed ConocoPhillips China, experts said CNOOC bore some responsibility.

Before the accident, the two platforms produced 22,000 barrels of oil per day for CNOOC, extracting about 8.4 million tons of crude per year. This accounts for about 20 percent of all crude taken from the Bohai Sea.

The two companies submitted a new plan for operating the oil rig and an environmental assessment report to the National Development and Reform Commission and the Ministry of Environmental Protection, but so far no approval for resuming production on the two platforms has been granted.

It was unclear if the two platforms had resumed production.

The SOA demanded that ConocoPhillips apologize for the spills, compensate for damage and warned the company that it planned to sue. Farmers and fisherman in Hebei Province hired lawyers as they sought compensation for spill-related losses, including damage to scallop beds.

On April 30, 2012, CNOOC and the ConocoPhillips China paid compensation of 1.68 billion yuan.

In such cases, political pressure usually leads to a settlement, but that prospect worries environmental lawyers. Most lawsuits over sea pollution in China lead to talks between local governments and polluters, and end with victims receiving much less than they sought in damages.

In China, polluters routinely escape punishment and even avoid public scrutiny. The government did not seek to penalize CNOOC after a 2010 leak at its Nanhai No. 1 platform in the Bohai Sea. The SOA did not notify the public of that leak at the time.
 
Also, after a coastal oil spill in Dalian, in the northeastern province of Liaoning, in 2010, the SOA did not seek compensation from state-owned China National Petroleum Corp. Local governments prevented the public from filing lawsuits against the oil company, but they said the government later paid individuals.