Drilling optimization through DHSA

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Read how Geovariances’ consultants help a copper mine in Brazil to reduce the grade uncertainty of ore concentrates to better meet customers’ requirements.

Drilling is one of the most relevant expenditures in the mining industry. This cost depends on the location, geology feature, and complexity of the operation. In general, it could typically cost 150 to 300 USD/meter drilled. To optimize the use of their drilling budget, a copper mining company based in Brazil asked Geovariances to assess the geological and, consequently, financial risks related to different drill hole spacings considering the elements mined, the tonnages produced, and the thresholds of grades on ore concentrates defined by contract with its customers.

The methodology proposed by Geovariances to address these questions includes the application of conditional simulations of the elements of interest using the real dataset available. Some are selected based on cluster analysis from the total realizations as the simulated realities that will form the basis of the study. The selected realizations are resampled in different spacings. These virtual drilling patterns are then used as an input for additional conditional simulations. The result of the conditional simulations with the virtual drilling patterns are then rescaled to the production increments, based on the actual production of the mine. The increments used are consistent with monthly or quarterly, and annual production. The risk assessment is performed within a confidence interval of 90% of the simulated results. From this study, the degree of precision related to each drill hole spacing is assessed and used as a guide for drilling campaigns, based on the uncertainties that the company is willing to deal with for each of the production increments tested.

The image below presents a schematic example of uncertainties related to different drill hole spacings for each production increment tested. Once the information is confidential, the values have been changed:

Geovariances - DHSA outputs

Based on the study carried out by Geovariances, the customer can define the ideal drilling spacing for each region of the mine, considering the thresholds of grade uncertainties of the ore concentrate accepted by contract with its customers.

The main gains for the mining company are the possibility to estimate the grades uncertainty for each drill hole spacing, production increment, and region mined and to use this information to optimize the use of the drilling budget. The company then has the means to guarantee that the ore concentrates will meet the requirements of its customers defined by contract, avoiding the payment of penalties for non-compliance with the agreements.