Geostatistical determination of the precision of global recoverable reserve estimates

Thesis/Dissertation · Wed Jan 01 00:00:00 EST 1986

OSTI ID:5307299

Buxton, B E

The goal of this research is to provide confidence interval estimates of global reserves. Reserves are assessed from the three recovery functions: recovered tonnage, quantity of metal, and ore grade, each evaluated at several cutoff grades and for a given selective mining unit size. The term global signifies that for the area being studied there are sufficient data to determine variogram functions specific to the area, and to reliably estimate histograms and the recovery functions by simple averaging of the data rather than by more complex methods such as kriging. The confidence intervals are constructed by assuming that the reserve estimates are unbiased, and that the estimation errors follow a normal distribution. Under these assumptions, construction of the confidence intervals requires only that the global reserve estimation variances be known. Calculation of these estimation variances will be based upon indicator-type variogram functions. These variograms quantify the spatial variability inherent to the recovery variables being studied. Different kinds of variograms are used for the different recovery functions and for the evaluation of those recovery functions at different cutoff grades. The method of compositing extension variances, classically used to assess the precision of global resource estimates, is utilized to account for the sampling density. Affine correction relations are adopted to account for mining selectivity. Five separate global areas have been considered, two simulated base metal deposits, and three different benches of an actual Carlin-type gold deposit. Various cutoff grades, sampling densities, and selection block sizes have been adopted. In all, over one thousand different reserve estimation problems have been considered in the testing.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 5307299
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
02 PETROLEUM
03 NATURAL GAS
04 OIL SHALES AND TAR SANDS
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
GEOLOGIC DEPOSITS
RESOURCE ASSESSMENT
CALCULATION METHODS
GOLD
MINERAL RESOURCES
ORES
RECOVERY
RESERVES
SAMPLING
STATISTICS
ELEMENTS
MATHEMATICS
METALS
RESOURCES
TRANSITION ELEMENTS
011000* - Coal
Lignite
& Peat- Reserves
Geology
& Exploration
020100 - Petroleum- Reserves- (-1989)
030100 - Natural Gas- Reserves- (-1989)
040100 - Oil Shales & Tar Sands- Reserves & Exploration- (-1989)
050100 - Nuclear Fuels- Reserves
Exploration
& Mining