Objectives/Scope: The Hydraulic Fracturing Test Sites (HFTS) are large collaborative field-based R&D projects funded by the US Department of Energy through the National Energy Technology Laboratory (NETL) and the E&P industry, with support from academia. The projects' main objective is to improve the understating of the hydraulic fracturing process through utilization of advanced diagnostics and collection of through-fracture cores to provide undisputable evidence and attributes of the created hydraulic fractures.

Methods/Procedures/Process: The HFTS-I is a field-based hydraulic fracturing research experiment located in the West Texas Permian (Midland) basin. At the test site, about $30 million was used to perform hydraulic fracturing research, concentrated around eleven horizontal wells fractured with over 400 stages in the upper and middle Wolfcamp formations as well as two recompleted legacy wells. Comprehensive field data was collected, including advanced diagnostics such as time-lapse cross-well seismic and microseismic surveys to measure hydraulic fracture attributes. To supplement the fracture diagnostics, two slant core wells were drilled through the created hydraulic fractures and over 850 feet of core was recovered, capturing many hundred hydraulic fractures in their natural state. The research project also completed a huff-and-puff experiment using field gas as injectant, to determine the effectiveness of such treatments for fractured shale Enhanced Oil Recovery (EOR).

Building on learnings and unanswered questions from HFTS-1, a second hydraulic fracturing research experiment (HFTS-2) has been commissioned in West Texas Permian (Delaware) basin. At the HFTS-2 eight new producing wells and two existing (legacy) wells were used to perform hydraulic fracturing research. Multiple science wells were drilled to sample and characterize the subsurface, including the collection of 540 feet of vertical core and 950 feet of high-angle through fracture core. The project also installed permanent fiber optic cables in 3 wells to monitor near wellbore signals during fracturing and to collect cross-well strain measurements. Other advanced diagnostics included a five-array microseismic survey, time-lapse geochemistry sampling and analysis, proppant log in a child well, and others.

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