Inferred reserves

Demonstrated reserve quantities are estabUshed by measurements including drillings surface sampling, etc. Inferred reserves are those derived from geological survey information, not by measurement of the extent of the particular reserve. Not included herein are identified marginal and speculative resources, such as the oil-field and geothermal brines and lithium-hearing clays. These latter reserves are speculative as to extent, not existence. Total undiscovered clays in the western United States are speculatively estimated at 15 x 10 t lithium (16). More detailed Hsts of reserves are also available (15,17). 

Inferred reserves are producible, but the assumption of their presence is based on limited physical evidence and considerable geologic extrapolation. This places them on the borderline of being considered undiscovered, and the accuracy of the estimate is very poor. 

This total is the sum of the proven, indicated and inferred reserves. 

The term inferred reserves is also commonly used in addition to, or in place of, potential reserves. Inferred reserves are regarded as having a higher degree of accuracy than potential reserves, and the term is applied to those reserves that are estimated using an improved understanding of reservoir frameworks. The term also usually includes those reserves that can be recovered by further development of recovery technologies. 

Note This term is equivalent to "Demonstrated Reserves" as defined in the resource/ reserve classification contained in the United States Geological Survey, Ci rcular 831,1980. Demonstrated reserves include measured and indicated reserves but exclude inferred reserves. 

Many sources, including the DOE, further categorize reserves, differentiating between proven reserves, indicated reserves, and inferred reserves. Each succeeding level indicates less certainty. Indicated reserves are what are deemed recoverable from known fields using improved recovery techniques. Inferred reserves are reserves thought to exist in identified fields but that have not been measured (Hinrichs 2002). 

Inferred reserves (unproved reserves) The term inferred reserves is commonly used in addition to, or in place of, potential reserves. 

Finally, the "inferred reserves" (category C2) are those which are tentatively determined as the resu It of the first exploration stage, in which the deposit has been prospected by means of a limited number of individually located boreholes, so that the chemical characteristics and structure of the deposit are known in an approximate and general way. 

World Reserves and Resources. A summary of demonstrated and inferred worldwide reserves of lithium is given in Table 2. The reserve base and the lithium equivalent represent resources in the ground. An overall lithium recoverabiUty of 65% for pegmatites and 33% for brines must be apphed to these values to estabUsh the amount of lithium that could eventually reach the marketplace (15). 

Inferred petroleum reserves, 18 595 Infinite dilution coefficients, 8 743 Infinite heat-transfer surface area, 13 253 Infinity point, 14 611... 

The northern Canadian Cordillera is one of the most well-endowed (richest) tungsten districts in the world (e.g., Dick Hodgson 1982). The highest grade tungsten deposit in this district is the Cantung mine, a world-class tungsten skarn with recent reserve estimates of 2.9 Mt at 1.21%W03 indicated and 0.73 Mt at 0.74%W03 inferred (Clow et al. 2006), and over 4.6 Mt at 1.6%W03 removed prior to temporary mine shut-down in 2003 (Rasmussen 2004). 

It is hoped that the terms donor and acceptor strengths will be reserved for inferences made about Lewis acid-base properties from data in the gas phase or poorly solvating solvents. This is to be contrasted with the more complex phenomena contributing to acidity and basicity. 

From the above discussion we infer that apart from the complexities of hydrolysis and mutarotation the most serious reservations concerning... 

The sum of all known and inferred (with reasonable probability) resources without consideration of economy of extraction is the resource base. The level of investigation is uneven among regions, and therefore additional amoimts may be discovered, particularly in areas not well studied today. Also, extraction methods vary with time, and new techniques (e.g., enhanced oil recovery) may alter the amormt of reserves assigned to a given physical resource. 

Current estimates of the available reserves and further resources of uranium and thorium, and their global distribution, are shown in Figs. 5.44-5.50. The uraruum proven reserves indicated in Fig. 5.44 can be extracted at costs below 130 US /t, as can the probable additional reserves indicated in Fig. 5.45. Figure 5.46 shows new and unconventional resources that may later become reserves. They are inferred on the basis of geological modelling or other indirect information (OECD and IAEA, 1993 World Energy Council, 1995). The thorium resource estimates are from the US Geological Survey (Hedrick, 1998) and are similarly divided into reserves (Eig. 5.47), additional reserves (Fig. 5.48) and more speculative resources (Fig. 5.49). The thorium situation is less well explored than that of uranium the reserves cannot be said to be "economical", as they are presently mined for other purposes (rare earth metals), and thorium is only a byproduct with currently very limited areas of use. The "speculative" Th-resources may well have a similar status to some of the additional U-reserves. 

At the 1999 price of 30 per kg U, the known (total of measured, indicated and inferred) world reserves of uranium which could be recovered economically was about 3.3 Mton U30g. This corresponds to 40 years consun tion assuming LWR s and presmt nuclear capacity to increase by 1 % a year. As energy cost increases, it is estimated that about 20 Mton can be recovered at a higher cost. Sea water contains some 4500 Mtons U but it is uncertain if U can be recovered economically from this huge resource. 

Statisticians normally use Latin sjrmbols to represent sample values, reserving the Greek alphabet for population parameters. Following this convention, we represent the population mean and standard deviation of our example by the Greek letters p and a, respectively. What can we infer about the values of these parameters, knowing the sample values xand s ... 

---