An Application of Direct Sequential Simulation and Co-simulation for Evaluating the Resource and Uncertainty of the Ncondezi Coal Deposit, Mozambique

The main objective of this work is to develop a model of the morphology and coal-quality variables of a sub-region of the Ncondezi coal deposit, Mozambique, with data supplied by the Ncondezi Coal Company. This coal deposit is characterized by a complex stratigraphy, with fine coal layers interleaved with layers of shales and sandstones. The morphological model consists of the spatial characterization of the random variable P(x) (proportion of coal). To model the coal-quality variables and because of the large number of variables and given that some pairs of variables exhibit high correlations, an approach involving simulation of principal components as secondary variables is used. A set of selected principal components are simulated using direct sequential simulation, and the coal-quality variables are then co-simulated conditional to the previously simulated principal component values. This approach works as a global co-regionalization model. The results of the morphological model and of the model of the coal-quality variables allow global coal reserves to be calculated as well as the quantities of coal to be parameterized as a function of the coal-quality variables.