Advanced Diagnostics Aid Understanding at Hydraulic Fracturing Test Site 2
Authors: Carpenter Chris 
Published: July 2023

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper URTeC 2021-5514, “Overview of Hydraulic Fracturing Test Site 2 in the Permian Delaware Basin (HFTS-2),” by Jordan Ciezobka, SPE, GTI. The paper has not been peer reviewed.

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The Hydraulic Fracturing Test Site 2 (HFTS-2) is a large collaborative field-based research and development program in the Permian Delaware Basin funded by the US Department of Energy through the National Energy Technology Laboratory and the exploration and production industry with support from academia. The project’s main objective is to improve the understanding of the hydraulic fracturing process through use of advanced diagnostics and collection of through-fracture cores to provide undisputable evidence and attributes of created fractures.

Project Background
The HFTS-2 project provides the opportunity to address the optimal development of a stacked pay resource that requires simultaneous drilling and completion of tens of thousands of wells across multiple geologic horizons, also known as cube development.
The project consists of a series of coupled analytic and field experiments in which research-quality data are acquired in dedicated research wells through full instrumentation at, and in proximity to, hydraulically fractured wells. Furthermore, the unique site design provides an opportunity to understand the effect of reservoir depletion because many child-well stages overlap parent-well areas. The extensive data set acquired was integrated and used to calibrate subsurface models and characterize fracture geometry and proppant distribution. Diagnostics and modeling efforts enabled comprehensive calculations of hydraulic fracturing’s vertical and lateral extent and production-depletion profiles and quantification of fracture growth bias for child-well stages that overlapped parent wells.
Results from the project culminated in the development of a series of optimization procedures for increased drilling and completion efficiency, reducing environmental footprint by producing the reservoir from fewer well pads and fracturing stages.

Test Site
The research well package consists of eight new producing wells, two existing parent wells, and two new dedicated science and observation wells drilled for this project. The new producing wells are landed in various Wolfcamp horizons and have lateral lengths of approximately 7,500 ft. The lateral sections of the wells are spaced approximately 660 ft apart. The two existing parent wells also are in the Wolfcamp formation and have lateral lengths of approximately 5,000 ft. The two new science wells were drilled from the same pad, positioned between laterals B3H and B4H. One science well is a vertical pilot hole used to characterize the reservoir through the collection of mud and drill-cutting samples, electric logs, and whole and sidewall cores. The well also was used to house diagnostic instrumentation. The second science well is a slant well drilled after all wells were stimulated and was used to collect whole cores through the created fractures. The slant core well was instrumented with pressure and temperature gauges to monitor reservoir depletion during production.