Police pushed the protesters behind barriers to clear the entrance, and the demonstrators dispersed after about a half hour.
Mayor Nutter, who addressed the conference Friday, took note of the protesters: "I hope you're taking advantage of everything Philadelphia has to offer, including respecting and appreciating the right to free speech which is oh so - oh so exceedingly exercised in the city of Philadelphia."
The protesters represent a shrill outcrop of an undercurrent of public discomfort with gas drilling that the coalition's public-relations campaign is attempting to address.
Kathryn Z. Klaber, the president of the shale coalition, promised the campaign would be "a robust process of answering the questions of residents of Southeastern Pennsylvania with facts, with sound science and with comprehensive research."
The centerpiece of the effort is a website, www.learnaboutshale.org.
The effort is an outgrowth of a similar campaign launched earlier this year called Ask About Shale. The outreach is being done at the request of public officials, who told the industry it was loosing the hearts-and-minds campaign in the Philadelphia area to anti-drilling activists, who have raised fears about the environmental and social effects of drilling.
K. Scott Roy, vice president of government and regulatory affairs for Range Resources, described the campaign as an attempt "to not take the approach that other industries have taken - to be dismissive of what we perceive to be nonlegitimate concerns. Our desire is to be responsible to all those concerns."
Industry executives were flanked by Michael Krancer, the secretary of the Department of Environmental Protection, and three members of the Pennsylvania Public Utility Commission.
Krancer, whose department regulates drilling activity, said it was "very appropriate" for him to appear on stage with industry representatives. "It's all about listening," he said. "It's all about disclosure."
One activist was unimpressed.
"The industry's own science, along with that of agencies, experts and experience on the ground in communities where drilling is happening shows us drilling and fracking harms communities," said Maya K. van Rossum, who heads the Delaware Riverkeeper Network. "And to suggest otherwise by presenting false or partial information is simply unfair, not to mention out-and-out deceptive."
Contact Andrew Maykuth at 215-854-2947, @Maykuth on Twitter or firstname.lastname@example.org.