The situation

ISR amenability, being the viability of a uranium deposit to be mined using ISR, requires two critical parameters; a permeable host formation and favourable hydro and geo-chemistries.

Porosity, and particularly free fluid porosity coupled with mineral and groundwater chemistry, form the factors required to properly model the required fluid volumes, injection rates, and lixiviant chemistry for effective mining. In addition, formation permeability (hydraulic conductivity) is also a primary driver in assessing resource recovery rate. 

Traditionally, formation porosity and permeability are measured on core samples in a lab. Core drilling and analysis can be expensive undertakings and slow to deliver final usable results. Alternatively, permeability and hydraulic conductivity can be determined via pump and slug tests. However, pump and slug tests require fully installed wells screened in the appropriate zone before testing can even take place, adding to the overall operation costs.

Wireline logging technologies are used extensively in uranium ISR because they offer faster data acquisition. Additionally, wireline technology is more cost-effective compared to alternative methods and provides a continuous dataset, making it a preferred choice for uranium exploration, delineation, and mining.

Technical solutions

WIREBmr™ is a downhole geophysics tool that measures water contained in subsurface environments safely and accurately. WIREBmr™ is specifically tuned to sense fluids within the pore network, enabling precise determination of the formation’s total porosity, mobile fluid content and bound fluid content. Formation permeability is also calculated without requiring additional wireline data. WIREBmr™ eliminates the need for other wireline methods that may not function well in PVC wells or heavily rely on local calibration, providing a reliable and safer alternative.

In situations where the overall water/brine content remains consistent throughout the borehole but the ratio of free to bound fluids varies, it's crucial to classify intervals as either an aquifer (containing abundant free fluids) or an aquitard (containing mostly bound or no fluids). With WIREBmr™, it becomes possible to break down the total porosity into different mobility categories, enabling accurate estimation of the effective porosity and the identification of fluids trapped in clay and shales, which will not flow under an injection/extraction regime.

The result

Using WIREBmr™ the mine geology team at Boss Energy now have increased confidence in the reliability of their geological interpretation, which was previously based on a combined gamma-gamma density/neutron and resistivity regime. In addition, the team has been able to generate area specific models for porosity and permeability where previously a reliance on sparsely sampled core and pump tests were the only option. 

Orica wishes to thank Honeymoon Mine and Boss Energy for their support and permission to publish this case study.

Author: Nick Jervis-Bardy