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Hydraulic Fracturing Test Site II (HFTS2) – Delaware Basin
Project Number
Last Reviewed Dated

The objective of this project is to conduct a field-based hydraulic fracturing research program in the Delaware Basin portion of the Permian Basin in West Texas. This project will advance hydraulic fracturing technology, optimize well spacing, and mitigate environmental impacts of shale development operations. The research will advance our understanding of the hydraulic fracturing process in shale reservoirs, thus enabling the design and execution of effective fracture stages that significantly contribute to production. Improved design and execution of fracture stages will also reduce the number of future infill wells drilled and reduce water volume and energy input. This project will build upon the learnings from the HFTS1 project and advance the understanding of hydraulic fracturing. 


Gas Technology Institute, Des Plaines, IL 60018


The Permian Basin is one of the most prolific oil and natural gas geologic basins in the United States (U.S.). It is central to America’s energy resurgence, enabled by development of the shale resources within U.S. geologic basins. The Permian-Delaware Basin produces more than 50,000 barrels of oil per day and is an area of active development. The Permian Basin is approximately 250 miles wide and 300 miles long across West Texas and southeastern New Mexico. It encompasses several sub-basins, including the Delaware Basin and the Midland Basin, where the HFTS1 test site was located. Given the complexity of shale formations, significant geotechnical differences occur within the respective basins over very short distances. The Delaware Basin is a deeper basin than the Midland with vertical well depths up to 10,000 feet. The Delaware Basin is also a geo-pressured basin, adding to the difference between the two basins. From a geologic and geotechnical perspective, industry considers them separate and distinct basins.

Despite the long history of hydraulic fracturing, the optimal number of fracturing stages during multi-stage fracture stimulation in horizontal wells is not known. In addition to the increased expense of multistage fracturing in horizontal wells, increasing the number of fracturing stages does not always correlate with an increase in production. The problem is the application of a uniform fracture stimulation design to all stages with no consideration for geological variations along the wellbore. The result is an inefficient use and a costly waste of energy and water. 

Optimization of the fracturing process requires an understanding of the cause-and-effect relationship between fracturing parameters and local geological properties at a given location along the wellbore. Realizing that the generalized rock mechanics theories and hypotheses are not truly applicable to fractured and laminated shales, quantifiable impacts of a shale’s geomechanical and depositional features are a prerequisite for design and implementation of optimized hydraulic fractures. The overarching goal of this project is to understand and define the relationships of shale geology and fracture dynamics using detailed field data that includes coring of the fracture domain. Analyses of the data will aid in updating fracture design models and improve the effectiveness of individual hydraulic fracture stages.


The HFTS2 field test site provides the opportunity to address the “billion-dollar problem,” or the optimal development of a “stacked pay” resource which requires simultaneous drilling and completion of tens-of-thousands of wells across multiple geologic horizons. Drilling too many wells' results in a waste of resources such as water, steel casings, and other infrastructure while adding to emissions issues and land footprint. Drilling too few wells, from the perspective of well spacing, leaves valuable resources in the ground. Research results from this project are expected to have positive impact on economic, environmental, and resource recovery factors.

Simultaneous drilling and completion of wells in multiple geologic formations can reduce the overall cost of oil and gas production on a per-well basis, thus providing more drilling locations in the future, even at lower oil/gas prices. Continued long-term production adds jobs and increases economic output of the producing region and the U.S. economy.

The greatest beneficial impact to be derived from the proposed research will be achieved through determination of optimum well spacing and hydraulic fracture design. If the resulting optimization leads to a resource recovery increase of 1%, an additional 1.6 billion barrels of oil could be recovered from the Permian Basin. This optimization further leads to elimination of many wells currently drilled at non-optimum well spacing. 

Accomplishments (most recent listed first)
  • All project data has been uploaded to NETL’s EDX for public distribution Arrangements have been made to distribute the very large raw fiber optic data through a 3rd party
  • Completed an integrated fracture simulation study in which multiple simulation models were built, and history matched using the unique HFTS2 dataset, and then design sensitivities were run to help optimize frac design parameters such as cluster spacing and well spacing.
  • HFTS-2 members presented and published 16 papers with HFTS-2 results and learnings at the 2021 Unconventional Resources Technology Conference in July 2021, in a HFTS-2 Special Session
  • Completed fracture description on over 1200 fractures contained in the core.
  • Completed proppant analysis on more than 300 core sludge samples.
  • Completed time-lapsed oil geochemistry analysis on four wells with five temporal sampling points.
  • Drilled a slant core well and recovered over 940 feet of whole core through the created fractures and installed 12 discrete pressure/temperature gages in the well.
  • Completed two production/pressure interference tests to assess reservoir pressure response and test new Rayleigh Frequency Shift Distributed Strain Sensing Fiber Optic interrogator technology.
  • Installed tubing and bottomhole pressure/temperature gages in all producing wells and placed wells on production.
  • Completed proppant analysis (proppant log) from mud returns during drilling of a child test well lateral.
  • Pumped 262 fracture stages while monitoring with various diagnostics, including Distributed Acoustic Sensor (DAS) and Distributed Temperature Sensing (DTS), microseismic, cross-well DAS strain, high-frequency surface pressure gages, bottomhole gages, and others.
  • Completed Diagnostic Fracture Injection Tests (DFIT’s) on four horizontal test wells.
  • Logged three horizontal wells.
  • Drilled remaining horizontal wells and installed permanent fiber optic cable in two wells, along with permanent toe and heel gages.
  • Finished drilling, coring, instrumenting, and casing the vertical pilot well; the vertical pilot well was instrumented with permanent behind casing fiber optic cable along the entire measured depth of the well and discrete pressure gages.
    • Completed core analysis on recovered vertical core.
  • Implemented a data sharing platform and created a framework for data management and data sharing with project members.
  • Acquired background data from Anadarko Petroleum (now Occidental) for ~24 wells in the vicinity of the test site.
  • Held multiple workshops with experts from the participating companies and DOE/NETL to develop a draft testing and field data acquisition plan.
Current Status

The project is complete. The Final Report can be viewed at link below.

Final Report:

Project Start
Project End
DOE Contribution


Performer Contribution


Contact Information

NETL – Gary Covatch ( or 304-285-4589)
GTI – Jordan Ciezobka ( or 847-768-0924)