Evaluation of Prediction Models for the Physical Properties in Fire-Flooding Exhaust Reinjection Process

The reinjection of the fire-flooding exhaust is a novel disposal process for handling the exhaust produced by the in-situ combustion technology. For reasonable process design and safe operation, it is of great significance to select an optimum property calculation method for the fire-flooding exhaust. However, due to the compositional particularity and the wide range of operating parameters during reinjection, the state equations in predicting the exhaust properties over the wide range of operating parameters have not been studied clearly yet. Hence, this paper investigates the applicability of several commonly-used equations of state, including the Soave–Redlich–Kwong equation, Peng–Robinson equation, Lee–Kesler–Plocker equation, Benedict–Webb–Rubin–Starling equation, and GERG-2008 equations. Employing Aspen Plus software, the gas densities, compressibility factors, volumetric coefficients, and dew points for five exhaust compositions are calculated. In comparison with the experimental data comprehensively, the result indicates that the Soave–Redlich–Kwong equation shows the highest precision over a wide range of temperature and pressure. The mean absolute percentage error for the above four parameters is 3.84%, 5.17%, 5.53%, and 4.33%, respectively. This study provides a reference for the accurate calculation of the physical properties of fire-flooding exhausts when designing and managing a reinjection system of fire-flooding exhaust.

Adumbrative Heterodox Dictum of Wellbore Aggregates From Sapient Recovery Factor Penchants For Honed Field Praxis

Puissant field planning is increasingly becoming a sophisticated quandary with less emphasis on parametric synergy with reservoir spasmodic acuity. This conundrum leads to inaccurate harbinger of the required number of wells to be drilled for future field development programs from existing production and reservoir data particularly at pressures above the bubble point which is a major sobriety as orchestrated in most recent simulators. The aim of this erudition is to compendiously carry out astute predictive heterodox principles of wellbore aggregates from critical recovery factor parameters for savvy field planning. The main objectives are to glean and develop new propinquities for differential pressures (ΔP), rock compressibilities (Co) and oil formation volume factors (Bo) for predicting the number of wells to be drilled and recovery factors (RF) by equating the simulated results and the theoretical model (Ezekwe, 2010). To elucidate, metaphorize and ruminate new models. Reservoir and economic data was carefully simulated using FAST-FEKETE Evolution software for initial 40 future oil wells. Average results were mathematically correlated with recovery factor model to produce new correlations to quickly re-jig field planning efficiency. Results of matched and validated compressibility factors, differential reservoir pressures and oil formation volume factors were correlated with field data from Ezekwe (2011) model. Results of compressibility factor showed increasing similar 3rd order polynomial converging correlation for both models but gave slight divergence with increasing number of wells and RF. Results of differential pressures gave linearly increasing correlation with number of wells and RF while the new model had a cross-over point at 6435.64 psi for 2 wells but slightly increased divergently with number of wells and RF. Results of oil FVF gave a good similar regression (R2) of 0.999 while both models showed decreasing 3rd order polynomial correlation comparison with number of wells but with slight divergent disparity with increased RF. To further validate the potency of this study, detailed comprehensive paired sample test gave standard deviation, standard error of mean and degree of freedom of 0.00356, 0.0012 and 8 for compressibility factors; 324.7, 102.68 and 9 for differential pressure while the oil formation volume factor gave 0.0067, 0.0021 and 9. The predictions obtained by the new model showed appreciable degree of consistency and accuracy with number of wells and RF. This is perhaps largely hinged on the capacity to cogently infuse field data with theoretical and simulated models effectively. This study has clearly shown that no special technique or rigorous computational procedures is required to plan future number of wells to be drilled in a field or perhaps estimate the required RF. Sequel to this, further research is encouraged to inculcate more correlations based on comprehensive field validation studies to improve the efficacy of this model.

A Novel Simplification for the Prediction of Natural Gas Compressibility Factor

The need for a simpler, effective and less expensive predictive tool for the estimation of natural gas compressibility factor cannot be exaggerated. An accurate prediction of gas compressibility factor is essential because it plays a definitive role in evaluating gas reservoir properties used in the estimation of gas reserves, custody transfer and design of surface equipment. In this present work, a novel explicit correlation and a highly sophisticated computer program were developed to accurately predict natural gas deviation factor. The research also aims to effectively capture the relationship between Pseudo-reduced temperature and pressure in relations to the Z-factor. In this study, 3972 digitized data points extracted from Standing and Katz’s Chart were regressed and analyzed using Microsoft Excel Spreadsheet, the extraction of this data was done using WebPlotDigitizer developed by Ankit Rohatgi of GitHub, Pacifica, CA, USA. The correlation was developed as a function of Pseudo-reduced temperature and pressure with tuned parameters distributed across 1.05 ≤ Tpr ≤ 3.0 and 0 < Ppr ≤ 8.0. Subsequently, the input (Tpr and Ppr values) of the feed data was used to validate the correlation and compare it with other known and published correlations. Statistical analysis of the results showed that a 99.8% agreement exists between the predicted and actual compressibility factors for the various test scenarios and case studies involving both sweet and sour gases. Also, the correlation was observed to outperform other models. Finally, the results were observed to perfectly mimic the Standing and Katz charts with an overall correlation coefficient of 99.76% and an adjusted R2 of 99.75%. The proposed correlation was subsequently used to develop a software using JavaScript. Undoubtedly, the proposed correlation and software are suitable for rapid and accurate simplification and prediction of natural gas compressibility factor.

Calculation of the compressibility factor of gas-saturated oils

The article deals with a hypothetical model of the molecular structure of degassed and gas-saturated oils developed on the basis of the J. I. Frankel’s hole theory of liquid. Based on this model, the author of the article obtained semiempirical dependences for calculating compressibility factors of degassed and gassaturated oils. The fact that the obtained dependences are based on the noted model gives the necessary physical validity to them and the specific physical content to the empirical parameters contained in them. As a result, semi-empirical dependences become theoretical. Corresponding calculations confirm that their scope broadens as the types of oils and conditions for their finding.

Volumetric Measurements of Methane-Coal Adsorption and Desorption Isotherms—Effects of Equations of State and Implication for Initial Gas Reserves

This study presents the effects of equations of state (EOSs) on methane adsorption capacity, sorption hysteresis and initial gas reserves of a medium volatile bituminous coal. The sorption experiments were performed, at temperatures of 25 °C and 40 °C and up to 7MPa pressure, using a high-pressure volumetric analyzer (HPVA-II). The measured isotherms were parameterized with the modified (three-parameter) Langmuir model. Gas compressibility factors were calculated using six popular equations of state and the results were compared with those obtained using gas compressibility factors from NIST-Refprop® (which implies McCarty and Arp’s EOS for Z-factor of helium and Setzmann and Wagner’s EOS for that of methane). Significant variations were observed in the resulting isotherms and associated model parameters with EOS. Negligible hysteresis was observed with NIST-refprop at both experimental temperatures, with the desorption isotherm being slightly lower than the adsorption isotherm at 25 °C. Compared to NIST-refprop, it was observed that equations of state that gave lower values of Z-factor for methane resulted in “positive hysteresis”, (one in which the desorption isotherm is above the corresponding adsorption curve) and the more negatively deviated the Z-factors are, the bigger the observed hysteresis loop. Conversely, equations of state that gave positively deviated Z-factors of methane relatively produced “negative hysteresis” loops where the desorption isotherms are lower than the corresponding adsorption isotherms. Adsorbed gas accounted for over 90% of the calculated original gas in place (OGIP) and the larger the Langmuir volume, the larger the proportion of OGIP that was adsorbed.

Statistical mechanics of hard spheres: the scaled particle theory of the hard sphere fluid revisited

The aim of this paper is to exhaust the possibilities offered by the scaled particle theory as far as possible and to confirm the reliability of the virial coefficients found in the literature, especially the estimated ones: B i for i > 11. In a previous article (J.Math.Phys.36,201,1995) a theoretical equation of state for the hard sphere fluid was derived making use of the ideas of the so called scaled particle theory which has been developed by Reiss et al.(J.Chem.Phys.31,369,1959). It contains two parameters which could be calculated. The equation of state agrees with the simulation data up to high densities, where the fluid is metastable. The derivation was besed on a generalized series expansion. The virial coefficients B 2 , B 3 and B 4 are exactly reproduced and B 5 , B 6 and B 7 to within small deviations, but the higher ones up to B 18 are systematically and significantly smaller than the values found in the literature. The scaled particle theory yields a number of equations of which only four were used. In this paper we make use of seven equations to calculate the compressibility factors of the fluid. They agree with the simulation data slightly better than those yielded by the old equation. Moreover, the differences between the calculated virial coefficients B i and those found in the literature up to B 18 are very small (less than 4 percent).