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Unconventional Yearbook 2018

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82 | January 2018 | 2018 UNCONVENTIONAL YEARBOOK | COMPLETION OPTIMIZATION bashing by preferentially pressurizing a portion of parent wells adjacent to planned child wells in advance of drilling the child well. "In this way, DT Ultravert serves the dual pur- pose of protecting existing wells from bashing and enhancing child wells," the company stated in a press release. WPX's Downey stressed understanding the dif- ference between well communication and actual production issues when considering the potential impact a child well may have on its parent well. "There's a fine line between well communication and actual production interference," he said. "Just because we're seeing pressure communication between wells doesn't mean the propped fracs are overlapping. Tracer technology and production analysis help us evaluate production sharing and interference." Fox said that in some cases, Encana's cube com- pletions design has resulted in the child wells out- performing its parent wells. "In plays like the Permian and Montney, where there are thousands of feet of stacked pay, it has become evident that efficient exploitation of the resource requires a three-dimensional development model, where wells are not only tightly spaced side by side, but also above and below one another," he said. "Using our cube approach minimizes the risk of communication and enhances productivity by creating a more complex fracture network." Fox said Encana works to minimize the risk of a child well's communication with the depleted reser- voir which can make subsequent wells less effective. "We enhance productivity by creating a more complex fracture network," he said. "We also improve our uptime by avoiding cleanouts due to offset frack hits." Aviles said far-field diversion methods is a tech- nology Schlumberger utilizes that helps reduce any negative impact on production from parent-child well interaction while fracturing. "Engineered for tightly spaced wells, far-field diversion constrains fracture growth using parti- cles to bridge only the fracture tip and thereby pre- vent excessive fracture length and height growth," he said. "The Broadband Shield fracture-geometry control service achieves this objective by minimiz- ing the risk of communicating with neighboring wells or fracturing into undesirable zones while increasing fracture complexity." Regarding parent-child well interactions (or infilled drilling programs), Halliburton's Ingram said that many reservoirs see a negative produc- tion impact in the parent well following the frac- ture of a child well, but not all do. He said that to deliver expected production from child wells, oper- ators often turn to technologies designed to better understand fracture spacing and delivery such as downhole fiber optics, which can help an operator understand if a child wells' fracture treatment is impacting a parent well's production. "We spend a lot of time thinking, designing and modeling around diversion technology and micro- proppant technologies that can alter how a fracture is being propagated and the length of the individ- ual fracture treatment in this pressure-depleted environment," Ingram said. "Because that's really what the child/parent phenomenon is—treating the child wells in the presence of pressure depletion." Consultant Kumolski said geologic and rock property modeling are key early steps to be taken to avoid fracture hits and well bashing. A better understanding of the reservoir's characteristics and how fractures are affecting those reservoirs could help avoid depleted production. "Whenever you go into child wells have a bet- ter understanding of where some of the fractures have gone," he said. "Once you start fracking the child wells, you start affecting the parent wells. Put together some better geological models, then go back and design on what the volumes of sand, what stages you want to perforate and what you'd want to fracture." Jeff Dutton, vice president of Longfellow Energy, said some operators increase pressures at the parent well prior to fracturing the child wells to maintain parent well production. In a study first discussed at the Unconven- tional Resources Technology Conference in 2017, Schlumberger evaluated the impact of well spac- ing and interference on production performance in the Permian Basin Avalon Shale play. As part of its study, Schlumberger leveraged the Kinetix stim- ulation software suite for design, optimization, exe- cution and evaluation for stimulation operations.

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