SpecialReport: Advancing Shale Science Once a well has reached its total depth, the actual well markers are incorporated into the seismic depth map along with the geosteering interpretation if there is a high confidence in the correlation. During this process, the geophysicist selects a regular gridding interval that fits the map data (i.e., every 400 feet or so) to recalculate and revise the seismic depth map to match the interpretation (Figure 4). With limited well control in an area of complex stratigraphy, the Trees Ranch proprietary 3-D dataset has been essential to the initial success of Parsley Energy's horizontal campaign in the southern Delaware Basin. Integrating the geology with the seismic has allowed for a more accurate depiction of the subsurface. Issues with seismic image quality and formation pressure variability in the area can create erroneous structures, but these are becoming more predictable as the seismic depth maps are fine-tuned with every new data point collected. Having seismic as a guide to aid in geosteering for predicting structural changes is a key component in executing a successful drilling program. Drilling these horizontal wells within the desired target window becomes more important as Parsley Energy evaluates moving to tighter-spaced vertical and horizontal target zones on multiwell pads. r Jennifer Hernandez joined Parsley Energy as a geologist in 2014 and currently is working the company's Delaware Basin asset. She has more than a decade of industry experience, with a focus on operations and field development. Hernandez holds a B.S. in geology from the University of Texas at Austin. JENNIFER HERNANDEZ J. Alexandra "Ali" Sloan is a geologist at Parsley Energy, where she works on the Delaware Basin development team. Before joining the company, she worked for Marathon Oil Corp. Sloan holds a B.A. in geology from The College of Wooster and an M.S. in geological sciences with an emphasis in petroleum and subsurface modeling from the University of Colorado at Boulder. J. ALEXANDRA "ALI" SLOAN John Terwilliger is a member of Parsley Energy's Delaware Basin team focused on Wolfcamp development. He has more than two decades of experience in seismic interpretation and modeling in onshore U.S. conventional and unconventional plays. Before joining Parsley Energy in 2014, Terwilliger worked as a seismic interpreter at Statoil DPNA and Brigham Oil & Gas. He holds a B.S. in electrical engineering from the University of Connecticut and an M.S. in geophysics from the University of Houston. JOHN TERWILLIGER MARCH 2018 69