Optimizing 3D efficiency function based on the ore detection probability and drilling costs to locate an exploratory boreholes network

Document Type : Research Article

Author

Dept. of Mining and Metallurgy, Yazd University

Abstract

Summary
In the earth sciences, a great deal of uncertainty modeling depends on subsurface interpretation. The exploratory borehole is one of the best tools for subsurface exploration and data gathering. In the mineral exploration project, the layout of boreholes is designed based on the available information and engineering judgment, which may result in a lack of information or redundant information in decision making. This paper presents a new algorithm to compute the parameters of the optimal exploratory boreholes network.
 
Introduction
There are three significant concepts in sampling design, including probabilistic geometry, geostatistical error management, and information theory. The probability of intersection between target and network was calculated as a function of the target geometry and its relative orientation with respect to the directional and dimensional properties of exploration network.
 
Methodology and Approaches
Designing of the optimal drilling network contains two main strategies: (i) maximize the detection (exploration) probability, (ii) minimize the cost of drilling. These two principles, which are two opposite points of each other. The beginning optimization stage of drilling network is determining the strike direction of the network that depends on the main direction and shape ratio (length to width) of the ore. In the following phase, the efficiency model (gross drilling return) is defined as the difference of the detection probability and cost function (as the two principals of optimization model). The ore detection probability was the function of ore geometry (directional and dimensional parameters), the ratio of ore length to drilling network length, and the angle of the borehole. Three types of ore geometry are considered: 1D (Vein model), 2D (band or layer model) and 3D (mass model).
 
Results and Conclusions
In this present study, the ore with three dimensional geometry was studied that were the primary model produced by geophysical investigations. The effective parameters of the drilling cost function are related to the length of the borehole, the type of drilling, and inclination of the borehole. To compute the optimal parameters, the partial derivative of efficiency model was solved based on the independent variables (the size of drilling network and the angle of borehole). Finally, according to local variety in the dip of deposit, the optimal orientation of boreholes was correct based on angle of surface effect.

Highlights

  • In the detection probabilistic approach, the Ore exploratory model was calculated based on the comparing of the directional and dimensional properties of target geometry and exploration network.
  • The 3D efficiency function (gross drilling return) aims to maximize the detection (exploration) probability and minimize the costs of drilling.
  • To compute the optimal parameters, the partial derivative of efficiency model was solved with respect to the size of drilling network, the inclination of borehole, and the local variety in the dip of deposit.

Keywords

Main Subjects

References

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Journal of Analytical and Numerical Methods in Mining Engineering
Volume 5, Issue 10 - Serial Number 10
February 2016
Pages 111-123

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History

  • Receive Date: 16 October 2015
  • Revise Date: 26 February 2016
  • Accept Date: 20 April 2016

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