Boundary modeling with uncertainty

• Author / Creator

  Mancell, Steven, A.

• Mineral exploration and mining are capital intensive and carry significant environmental and societal
  considerations. The feasibility of prospective mining operations hinges on a series of engineering
  decisions. The mineral resource estimation of the quality and quantity of resources greatly influences
  these decisions. Boundary modeling for defining subsurface geology is an essential aspect of the
  mineral resource estimation workflow. The proper spatial distribution of geological domains for
  further estimation is integral to having accurate and precise models. Uncertainty in the boundary
  and resource is quantifiable and is a result of sparse sampling and complex geology. Consequences
  of poorly defined boundaries include dilution of ore material, smearing of grade into uneconomical
  rock, and increased uncertainty in the deposit tonnage. These consequences directly impact the
  economic, environmental, and societal feasibility of operations.
  Boundary modeling workflows commonly use implicit techniques that automatically derive domain
  extents from data. These models are explicitly checked and edited to ensure the numerical model
  reflects known geological attributes. This deterministic approach generates a single model output
  and does not carry a measure of uncertainty. Stochastic approaches to boundary modeling capture
  short scale variability of the geology; however, imparting geological knowledge on the model is
  difficult.
  This thesis develops a new implicit methodology for boundary modeling that provides globally
  unbiased models with uncertainty. The indicator approach maps a field of probabilities and applies
  a threshold that results in an extracted boundary. Uncertainty assessment by varying the indicator
  thresholds provides eroded and dilated boundaries and a zone of uncertainty. Boundary definition is
  a critical and early step in resource estimation. The modeling of subsurface geology from sparse drill
  holes carries significant uncertainty. The results of this thesis provide a novel approach to boundary
  modeling with uncertainty. The geostatistical techniques and concepts are reviewed, the proposed
  framework outlined, and implementation, including case studies, are undertaken.

• Subjects / Keywords

  • boundary modeling
  • geostatistics

• Graduation date

  Spring 2021

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-09pp-3v04

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.