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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 20 (1988), S. 955-972 
    ISSN: 1573-8868
    Keywords: oil and gas ; resource appraisal ; play analysis ; probability models ; analytic methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The geologic appraisal model that is selected for a petroleum resource assessment depends upon purpose of the assessment, basic geologic assumptions of the area, type of available data, time available before deadlines, available human and financial resources, available computer facilities, and, most importantly, the available quantitative methodology with corresponding computer software and any new quantitative methodology that would have to be developed. Therefore, different resource assessment projects usually require different geologic models. Also, more than one geologic model might be needed in a single project for assessing different regions of the study or for cross-checking resource estimates of the area. Some geologic analyses used in the past for petroleum resource appraisal involved play analysis. The corresponding quantitative methodologies of these analyses usually consisted of Monte Carlo simulation techniques. A probabilistic system of petroleum resource appraisal for play analysis has been designed to meet the following requirements: (1) includes a variety of geologic models, (2) uses an analytic methodology instead of Monte Carlo simulation, (3) possesses the capacity to aggregate estimates from many areas that have been assessed by different geologic models, and (4) runs quickly on a microcomputer. Geologic models consist of four basic types: reservoir engineering, volumetric yield, field size, and direct assessment. Several case histories and present studies by the U.S. Geological Survey are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-8868
    Keywords: Oil resources ; probabilistic methodology ; resource appraisal ; computer aggregation ; world estimates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The U.S. Geological Survey assessed all significant sedimentary basins in the world for undiscovered conventionally recoverable crude-oil resources. Probabilistic methodology was applied to each basin assessment to produce estimates in the form of probability distributions. Basin probability distributions were computer aggregated to produce resource estimates for the entire world. Aggregation was approximated by a three-parameter lognormal distribution by combining the first three central moments of basin distributions. For purposes of experiment and study, world aggregation was conducted under four different sets of assumptions. The four cases are (1) dependent assessments of all basins, (2) dependent assessments within continental areas, but independent assessments among continental areas, (3) dependent assessments within countries, but independent assessments among countries, and (4) independent assessments of all basins. Mean estimate remained the same in all four cases, but the width of interval estimate formed using the 95th and 5th fractiles decreased with reduced dependency in going from first to fourth case.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Natural resources research 1 (1992), S. 153-162 
    ISSN: 1573-8981
    Keywords: Oil and gas assessment ; Analytic probability ; Play analysis ; United States
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A geostochastic system called FASPF was developed by the U.S. Geological Survey for their 1989 assessment of undiscovered petroleum resources in the United States. FASPF is a fast appraisal system for petroleum play analysis using a field-size geological model and an analytic probabilistic methodology. The geological model is a particular type of probability model whereby the volumes of oil and gas accumulations are modeled as statistical distributions in the form of probability histograms, and the risk structure is bilevel (play and accumulation) in terms of conditional probability. The probabilistic methodology is an analytic method derived from probability theory rather than Monte Carlo simulation. The resource estimates of crude oil and natural gas are calculated and expressed in terms of probability distributions. The probabilistic methodology developed by the author is explained. The analytic system resulted in a probabilistic methodology for play analysis, subplay analysis, economic analysis, and aggregation analysis. Subplay analysis included the estimation of petroleum resources on non-Federal offshore areas. Economic analysis involved the truncation of the field size with a minimum economic cutoff value. Aggregation analysis was needed to aggregate individual play and subplay estimates of oil and gas, respectively, at the provincial, regional, and national levels.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Natural resources research 4 (1995), S. 233-241 
    ISSN: 1573-8981
    Keywords: Fractals ; Pareto distribution ; 20/80 law ; Probability ; Petroleum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Fractal properties of the Pareto probability distribution are used to generalize “the 20/80 law.” The 20/80 law is a heuristic law that has evolved over the years into the following rule of thumb for many populations: 20 percent of the population accounts for 80 percent of the total value. The generalp100/q100 law in probabilistic form is defined withq as a function ofp, wherep is the population proportion andq is the proportion of total value. Using the Pareto distribution, thep100/q100 law in fractal form is derived with the parameterq being a fractal, whereq unexpectedly possesses the scale invariance property. The 20/80 law is a special case of thep100/q100 law in fractal form. Thep100/q100 law in fractal form is applied to petroleum fieldsize data to obtainp andq such thatp100% of the oil fields greater than any specified scale or size in a geologic play account forq100% of the total oil of the fields. The theoretical percentages of total resources of oil using the fractalq are extremely close to the empirical percentages from the data using the statisticq. Also, the empirical scale invariance property of the statisticq for the petroleum fieldsize data is in excellent agreement with the theoretical scale invariance property of the fractalq.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 16 (1984), S. 797-808 
    ISSN: 1573-8868
    Keywords: oil ; gas ; resource appraisal ; probability ; Monte Carlo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Probabilistic methodology used by the U.S. Geological Survey is described for estimating the quantity of undiscovered recoverable conventional resources of oil and gas in the United States. A judgmental probability distribution of the “quantity of resource” and its properties is determined for a geologic province or basin. From this distribution, point and interval estimates of the quantity of undiscovered resource are obtained. Distributions and their properties are established for each of the following resources: (1) oil and nonassociated gas from estimates of the probability of the resource being present and the conditional probability distribution of the quantity of resource given that the resource is present, (2) associated-dissolved gas from its corresponding oil distribution, (3) total gas, (4) oil and total gas in two or more provinces. Computer graphics routines are illustrated with examples from the U.S. Geological Survey Circular 860.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical geology 25 (1993), S. 59-80 
    ISSN: 1573-8868
    Keywords: substitution method ; qualified data ; lognormal distribution ; environmental science
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Geochemical data are commonly censored, that is, concentrations for some samples are reported as “less than” or “greater than” some value. Censored data hampers statistical analysis because certain computational techniques used in statistical analysis require a complete set of uncensored data. We show that the simple substitution method for creating an uncensored dataset, e.g., replacement by3/4 times the detection limit, has serious flaws, and we present an objective method to determine the replacement value. Our basic premise is that the replacement value should equal the mean of the actual values represented by the qualified data. We adapt the maximum likelihood approach (Cohen, 1961) to estimate this mean. This method reproduces the mean and skewness as well or better than a simple substitution method using3/4 of the lower detection limit or3/4 of the upper detection limit. For a small proportion of “less than” substitutions, a simple-substitution replacement factor of 0.55 is preferable to3/4; for a small proportion of “greater than” substitutions, a simple-substitution replacement factor of 1.7 is preferable to4/3, provided the resulting replacement value does not exceed 100%. For more than 10% replacement, a mean empirical factor may be used. However, empirically determined simple-substitution replacement factors usually vary among different data sets and are less reliable with more replacements. Therefore, a maximum likelihood method is superior in general. Theoretical and empirical analyses show that true replacement factors for “less thans” decrease in magnitude with more replacements and larger standard deviation; those for “greater thans” increase in magnitude with more replacements and larger standard deviation. In contrast to any simple substitution method, the maximum likelihood method reproduces these variations. Using the maximum likelihood method for replacing “less thans” in our sample data set, correlation coefficients were reasonably accurately estimated in 90% of the cases for as much as 40% replacement and in 60% of the cases for 80% replacement. These results suggest that censored data can be utilized more than is commonly realized.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 1985-05-01
    Print ISSN: 1874-8961
    Electronic ISSN: 1874-8953
    Topics: Geosciences , Mathematics
    Published by Springer
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  • 8
    Publication Date: 1988-11-01
    Print ISSN: 1874-8961
    Electronic ISSN: 1874-8953
    Topics: Geosciences , Mathematics
    Published by Springer
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  • 9
    Publication Date: 1997-03-01
    Print ISSN: 1874-8961
    Electronic ISSN: 1874-8953
    Topics: Geosciences , Mathematics
    Published by Springer
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  • 10
    Publication Date: 1993-01-01
    Print ISSN: 1874-8961
    Electronic ISSN: 1874-8953
    Topics: Geosciences , Mathematics
    Published by Springer
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