AAPG EXPLORER Photos courtesy <strong>of</strong> Terry Engelder Penn State University pr<strong>of</strong>essor (and AAPG member) Terry Engelder, whose long connection with the Marcellus Shale has brought him international recognition for his expertise. Engelder earns high pr<strong>of</strong>ile Marcellus Turns Penn Pr<strong>of</strong> Into a ‘Celebrity’ By LOUISE S. DURHAM, EXPLORER Correspondent 42 MAY 2013 WWW.AAPG.ORG Tell Terry Engelder he’s famous, and he comments wryly, “If you say so.” Engelder, pr<strong>of</strong>essor <strong>of</strong> geosciences at Pennsylvania State University, has long been an expert on the Devonian black shales. His pr<strong>of</strong>ile escalated dramatically with the onset <strong>of</strong> the now-renowned Devonian age Marcellus Shale play, which spans a distance <strong>of</strong> 400 miles, trending northeastward from West Virginia and into New York. Not surprisingly, his pr<strong>of</strong>ile also will be large at the upcoming AAPG Annual Convention and Exhibition in Pittsburgh, conveniently set close to Engelder’s own backyard. At ACE, Engelder’s listed as a supporting coauthor for three technical talks that will be presented – all dealing with the Marcellus Shale – and he’ll be a leader on the field trip “Devonian Gas Shales <strong>of</strong> the Appalachian Basin.” Engelder’s connection to Marcellus geology goes back decades, but his tie to the shale play began garnering attention in late 2011, when Range Resources announced initial test rates between 1.4 and 4.7 mcf/d for five horizontal wells drilled in the Marcellus. That announcement essentially coincided with a press release from Penn State, noting that Engelder, working in conjunction with fellow AAPG member Gary Lash, a geoscience pr<strong>of</strong>essor at SUNY Fredonia, had estimated the recoverable gas from the Marcellus Shale to be 50 Tcf. The play quickly acquired legs. “That was my initial volumetric calculation, which was designed to be very conservative,” Engelder said. “When production data became available, I did a statistical analysis on the very first data. “As a result <strong>of</strong> this, I thought ultimately that under favorable price conditions the Marcellus would yield as much as 489 Tcf,” he said. “By favorable, I mean something like $8 to $10 per Mcf.” Joints and a Woman’s Legacy Engelder began mapping rocks in the Appalachian Basin, including the gas shales, in the late 1970s. He published his first paper on the topic in 1980 in the Journal <strong>of</strong> Geophysical Research. The publication kicked <strong>of</strong>f his now-longtime consulting business with industry, when management at a division <strong>of</strong> Shell read the paper in the mid-1980s and contacted him for input on the Antrim Shale, where they were drilling for gas. Natural hydraulic fracturing in the basin was confirmed in a series <strong>of</strong> papers by Engelder and various co-authors. “The play is all about the fractures in the rock and how you tap into them,” he said. “The Marcellus has two sets <strong>of</strong> vertical fractures, or joints – the J1 and the J2. “The more dense, more closely spaced east-northeast trending J1s are cross-cut by the less well developed northwesttrending J2 joints,” he noted. Engelder emphasized the fractures and joints were first discovered long ago by a woman geologist, Pearl Gertrude Sheldon. Sheldon, a structural geologist, earned her doctorate from Cornell University in 1911, according to a Cornell Press-issued book about the Marcellus penned by Tom Wilber. Her doctoral thesis reportedly See Engelder, page 44
AAPG EXPLORER WWW.AAPG.ORG MAY 2013 43