Smoothing effect, conditional bias and recoverable reserves.

CIM Bulletin, Vol. 91, No. 1019, 1998

Guocheng Pan, GeoSight, Inc., Highlands Ranch, Colorado, United States

Although many factors play roles in the estimation of recoverable reserves, smoothing effect and conditional bias are considered major geostatistical issues in the estimation. This paper introduces measures for smoothing effect and conditional bias, and provides insights into their relation to the estimation of recoverable reserves. Both smoothing effect and conditional bias are intrinsic to the information effect and kriging estimators. For a given level of drilling information, however, it is possible to identify the optimal search radius that minimizes conditional bias. Furthermore, it is also feasible to define variance correction factor for reduction of the smoothing effect from exploration block models. Both of these components are key to the accurate estimation of recoverable reserves.

Keywords: Geology, Ore reserve estimation, Smoothing effect, Conditional bias, Recoverable reserves, Gold deposits.