Volumetric Behavior of Oil and Gas from the Rio Bravo Field

Sage, B. H.; Reamer, H. H.

doi:10.2118/941179-g

Cited by 3 publications

(1 citation statement)

References 3 publications

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“…Because field conditions generally restrict us to the use of these simple parameters, several workers have investigated empirical correlations that would permit prediction of "shrinkage of crude oils" attendant upon their production from the reservoir from measurements of gas-oil ratio, tankoil gravity, gas gravity, and reservoir temperature and pressure. Such correlations evolved from the work of many investigators: Sage and Reamer ( 1941), Standing and Katz ( 1942b), Katz ( 1943), Sage and Olds (1947), and Standing (1947Standing ( , 1948.…”

Section: Crude Oilismentioning

confidence: 99%

Mass properties of sedimentary rocks and gravimetric effects of petroleum and natural-gas reservoirs

McCulloh¹

1967

Professional Paper

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Section: Crude Oilismentioning

confidence: 99%

Mass properties of sedimentary rocks and gravimetric effects of petroleum and natural-gas reservoirs

McCulloh¹

1967

Professional Paper

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Two New Density Correlations

Chien

Monroy

1986

SPE Annual Technical Conference and Exhibition

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The Liquid density predicted by the Peng-Robinson (P-R) equation of state is often off by 10% or more at temperature and pressure conditions encountered in most reservoirs. To improve the density predictions, two new density correlations have been developed. The first correlation is based on the chain-of-rotators (COR) equation of state and the second is based on the three-parameter Peng-Robinson (PR3) equation of state. The COR correlation is applicable to wider pressure and temperature ranges, but is computationally expensive. It is suited for interpreting fluid-analysis data, where no extensive phase-behavior calculations are needed. On the other hand, the PR3 correlation is more limited in its application range, but is computationally more efficient.It is particularly suited for compositional reservoir simulation where many density calculations are repeatedly carried out.In general, both correlations are comparable to the Standing-Katz correlation for liquid-density calculation and comparable to the P-R equation of state for vapor-density calculation. However, they are superior to the Standing-Katz correlation for liquid mixtures near critical points or liquid mixtures at high pressures.Overall, the COR equation of state gives an average prediction error of 1. 9% for liquid densities and 2.7% for vapor densities, and the PR3 gives an average prediction error of less than 2% for both liquid and vapor densities. The required inputs are any two of the following properties for each pseudocomponent: molecular weight, specific gravity, and normal boiling point. This easy input requirement makes the correlations very attractive for engineering uses.References and Illustrations at end of paper.

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Fundamental PVT Calculations for Associated and Gas/Condensate Natural-Gas Systems

Sutton

2007

SPE Reservoir Evaluation &Amp; Engineering

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Summary Problems with existing procedures used to estimate gas pressure/volume/temperature (PVT) properties are identified. The situation is reviewed, and methods are proposed to alleviate these problems. Natural gases are derived from two basic sources: associated gas, which is liberated from oil, and gas condensates, where hydrocarbon liquid, if present, is vaporized in the gas phase. The two gases are fundamentally different in that a high-gravity associated gas is typically rich in ethane through pentane, while gas condensates are rich in heptanes-plus. Additionally, either type of gas may contain nonhydrocarbon impurities such as hydrogen sulfide, carbon dioxide, and nitrogen. Failure to distinguish properly between the two types of gases can result in calculation errors in excess of those allowable for technical work. Sutton (1985) investigated high-gravity gas/condensate gases and developed methods for estimating pseudocritical properties that resulted in more-accurate Z factors. The method is suitable for all light natural gases and the heavier gas/condensate gases. It should not be used for high-gravity hydrocarbon gases that do not contain a significant heptanes-plus component. The original Sutton database of gas/condensate PVT properties has been expanded to 2,264 gas compositions with more than 10,000 gas-compressibility-factor measurements. A database of associated-gas compositions containing more than 3,200 compositions has been created to evaluate suitable methods for estimating PVT properties for this category of gas. Pure-component data for methane (CH4), methane-propane, methane-n-butane, methane-n-decane, and methane-propane-n-decane have been compiled to determine the suitability of the derived methods. The Wichert (1970) database of sour-gas-compressibility factors has been supplemented with additional field and pure-component data to investigate suitable adjustments to pseudocritical properties that ensure accurate estimates of compressibility factors. Mathematical representations of compressibility-factor charts commonly used by the engineering community and methods used by the geophysics community are investigated. Generally, these representations/methods are robust and have been found suitable for ranges beyond those recommended originally. Natural-gas viscosity, typically estimated through correlation, has been found to be inadequate for high-gravity gas condensates, requiring revised procedures for accurate calculations. Introduction Since its publication, the Standing and Katz (1942) (SK) gas Z-factor chart has become a standard in the industry. Several very accurate methods have been developed to represent the chart digitally. The engineering community typically uses methods published by Hall and Yarborough (1973, 1974) (HY), Dranchuk et al. (1974) (DPR), and Dranchuk and Abou-Kassem (1975) (DAK). These methods all use some form of an equation of state that has been fitted specifically to selected digital Z-factor-chart data published by Poettmann and Carpenter (1952). The geophysics community typically uses a method developed by Batzle and Wang (1992) (BW). Recently, Londono et al. (2002) (LAB) refitted the chart with an expanded data set, resulting in a modified DAK method. They provided two equations: one fit to an expanded data set from the SK Z-factor chart and another that included pure-component data. A general gas Z-factor chart, such as the one developed by Standing and Katz (1942), is based on the principle of corresponding states (Katz et al. 1959). This principle states that two substances at the same conditions referenced to critical pressure and critical temperature will have similar properties. These conditions are referred to as reduced pressure and reduced temperature. Therefore, if two substances are compared at the same reduced conditions, the substances will have similar properties. In the context of this paper, the property of interest is the gas Z factor. Mathematically, the SK chart relates Z factor to reduced pressure and reduced temperature.

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Volumetric Behavior of Oil and Gas from the Rio Bravo Field

Cited by 3 publications

References 3 publications

Mass properties of sedimentary rocks and gravimetric effects of petroleum and natural-gas reservoirs

Mass properties of sedimentary rocks and gravimetric effects of petroleum and natural-gas reservoirs

Two New Density Correlations

Fundamental PVT Calculations for Associated and Gas/Condensate Natural-Gas Systems

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