Pending resolution, the smaller of the reserves estimates might be classified as proved, and the larger one as proved plus probable or proved plus probable plus possible, depending on the degree of uncertainty. Because of potential differences in uncertainty, caution should be exercised when aggregating reserves of different classifications. Most statistical data on RE in the U. The second term in the square brackets is used to calculate the adsorbed gas in the coal matrix.
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Fauzragore GWC Coal Handbook — Google Books The method of estimation is called probabilistic [our emphasis] when the known geological, engineering, and economic data are used to generate a range of estimates and their associated probabilities. Many perhaps most coalbed wells producing from coal that has low to moderate permeability will exhibit a wide range of hyperbolic declines, underscoring the need for suitable analogs.
The condensate REs are significantly different for all three reservoirs. American Oil and Gas Investor 19 6: Continuous monitoring of performance, then, is essential in reserve estimation by computer simulation—indeed, by any method! Such a review might reveal one or more causes e. J Pet Technol 40 2: SPE Res Eng 4 4: One should investigate these possibilities before using an isoultimate recovery map to estimate reserves for undrilled tracts.
Analytical analogy methods include using recovery factors e. Despite the still widespread use of deterministic methods for reserves estimation, there are several scenarios in which a probabilistic approach might be more gwv. The statistical frequency distribution of ultimate recovery—initial reserves—for wells in a common reservoir or geologic trend typically can be approximated with a log-normal frequency distribution. The widespread use of 3D seismic methods has increased confidence in the guiding of development drilling and defining of reservoir size and extent, especially in certain geographic locations.
A specific reserves estimate might involve one or more such methods. APFC EXAM SYLLABUS PDF In a scenario where there is a long history of settled production and, consequently, a regression coefficient approaching unity, such a distinction is insignificant; however, where there is a relatively short, erratic production history and, consequently, a regression coefficient significantly less than unity, the distinction might be significant.
Wedging on the hanbdook side reflects loss of structure between HKO and LKO, whereas thinning of the net oil contours to the northeast and southwest reflects thinning of the net oil sand.
Lacking such support, however, the projection should be confirmed through volumetric means before booking the forecast volumes as proved reserves. The Practice of Reservoir Engineering, Vol.
Because all these reservoir aspects seldom, if ever, are similar, judicious compensating adjustments from analogous to subject reservoir usually are needed. Reserves that are to be produced through the application of established improved recovery methods are included in the proved classification when 1 successful testing by a pilot ywc or voal response of an installed program in the same or an analogous reservoir with similar rock and fluid properties provides support for the analysis on which the project was based, and 2 it is reasonably certain that the project will proceed.
Linear, Cartesian trends of f o vs. Analyzing each well in a common reservoir often ywc appropriate for estimating reserves, particularly for a fully developed reservoir being produced under the control of a single operator; however, when individual wells are not analyzed, be aware of the potential for interwell interference to affect individual well-drainage patterns. Coal Conversion Facts Thomeer  parameter for capillary pressure curves. Infill Drilling in the Moxa Arch: For deterministic estimates, quantities for each of the three reserves categories of proved, probable, and possible are estimated, and the evaluator is cautioned not to add these quantities together because of the differing degrees of uncertainty associated with each.
In many areas, estimates of rock properties—porosity, initial water saturation, and net pay—made from wireline logs are subject to considerable uncertainty. Other Reserves Definitions Other petroleum-producing countries and regulatory authorities have promulgated petroleum reserves definitions that are recognized and based on years of development and sound engineering judgment, but none—however important in their sphere of influence—with such far-reaching consequences as the U.
During pressure reduction of reservoir fluids, the resultant stresses on reservoir rocks differ from those on core samples during hydrostatic testing in the laboratory. Plots of f o vs. Certain SABs published after Regulation S X  concern the application of financial accounting and disclosure rules for oil and gas producing activities. Federated States of Whatever. In most cases, the primary production stream volumes are forecast, and secondary products are estimated using constant or variable indices—primarily GOR or CGR.
Probabilistic Procedures Probabilistic procedures recognize that uncertainties in input data and equations to calculate reserves may be significant. Historically, production projections based on such analyses have been classified as proved reserves. Typically, faults with a throw of less than the thickness of the productive formation are assumed to be nonsealing. Most 10 Related.
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