A man was arrested for obstruction during an anti-drilling protest at Woodburn forest outside Carrickfergus.
Exploratory oil drilling is taking place at the forest by the company InfraStrata.
Protesters have claimed the drilling is putting at risk drinking water to many thousands of homes, something Infratrata and Northern Ireland Water have denied.
Thousands of homes are served by the nearby reservoirs.
The Stop the Drill protest has been backed by environmental campaigners, including Hollywood star Mark Ruffalo, who was the Hulk.
One of the drills for the test work was due to arrive on site on Monday.
Police had to close the Paisley Road because of the protest.
A protester climbed onto a drill as the lorry carrying it was making its way onto the site.
Mark Chapman told supporters he had enough food to last two days.
"I'm upholding environmental law," he said to cheers from the protesters.
"My understanding is that it is possible to commit a small crime to prevent a larger one."
Mr Chapman said he had come equipped and was prepared to chain himself to the drill if necessary.
The 57-year-old, after being warned, was then arrested for obstructive sitting. He was released on police bail at the scene.