Sigra recently delivered a comprehensive geological and geotechnical analysis project for Hydrostor compressed air storage project at the Potosi Mine site in Broken Hill. Sigra’s involvement was primarily in working with Deepcore who drilled two near horizontal 460 m long holes from underground.

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Extent of Work:

  • Core Logging: Detailed lithological and structural core logging.
  • Rock Property Testing: Sigra tested core triaxially for its Young’s moduli and Poisson’s ratios, conducted cyclic uniaxial testing and point load testing. A large number of point load tests were also conducted. The focus was on determining anisotropic elastic properties and the likely failure modes.
  • Stress Measurement: Using Sigra’s IST 3D overcore cell. This required results from the triaxial and cyclic uniaxial testing for the determination of stress from measured strains.
  • Geophysical Logging: Acoustic televiewer, full-wave sonic, and natural gamma logging for detailed structural and material information.
  • Permeability Testing: This involved conducting either injection fall-off or drill stem tests over the entire borehole lengths in 29 m increments with so that no section of the boreholes was left untested. Transient analysis was used to enable the determination of true permeability, ground water pressure and the effective radius of investigation of each test.

Challenges and Innovations:

  • Development of a customised geophysical logging system compatible with underground constraints.
  • Rapid adaptation of equipment to air-powered systems, addressing strict mine safety regulations prohibiting mains power.
  • Overcoming logistical hurdles, including tight timelines and unexpected mine shutdowns, while maintaining technical excellence.

Results:

Sigra’s work delivered critical data on geological conditions, stress profiles, rock properties and importantly permeability. These insights have provided Hydrostor with the essential information needed to proceed with the compressed air storage facility design.

Why Choose Sigra?

This project underscores Sigra’s ability to:

  • Deliver reliable data that reduces risk and enables informed decisions to be made in underground projects.
  • Design and innovate to overcome challenging operational constraints.
  • Advise on the best and most economical way to obtain the right information for your project.

Partner with Sigra for your next project to benefit from geotechnical expertise and proven results.