Thi s paper presents a mult i component surface tension correlation based on scaling theory. In addition to particular exponents employed. the correlation contains two new features: (1) A corresponding-states equation is derived for a correlation coefficient. commonly referred to as a parachor.As a result. the hydrocarbon pseudocomponent parachors can be calculated through this equation. once their pseudocritical properties are estimated.(2) An approach is proposed to calcu-1 ate the parachors of mi xtures. In contrast to the conventional approach. which calculates the mixture parachor via molar mixing of component parachors, this approach first obtains the pseudocrtical properties of the mixture and then employs the correspondi ng-states equat i on to cal cul ate the mixture parachor.
The assumption of ideal solution for the electrolyte solution in many mechanistic studies of enhanced oil recovery processes may be oversimplified because the mean ionic activity coefficient of an electrolyte is very sensitive to the mixture composition. A thermodynamic model is developed to account for the nonideality of electrolyte solutions and to serve as a tool for a more rigorous mechanistic study of enhanced oil recovery processes.The model takes into account three important molecular and ionic force contributions: the long range ion-ion electrostatic force contribution, the intermediate range ion-solvent interaction (solvation) contributio~ and the short range force contribution of all species.It is demonstrated that the model can correlate the solution behavior of strongly polar and nonpolar nonelectrolytes as well as strong electrolytes over a wide range of concentrations.The solvation contribution is found to be important in. correl ati ng the thermodynamic properties, especially, the salting out of nonelectrolytes in aqueous solutions.Comparison shows that the new model is four times better than Chen's model (1982) in correlating the mean ionic activity coefficients.The parameters of sodium chloride, sodium hydroxide and calcium cation as well as magnesium cation are determined in this study.These parameters wi 11 be useful for the mechanistic study of alkaline flooding processes and surfactant/polymer flooding processes. Furthermore, the model employs the group contri bution concept. Therefore, it can be used to estimate the solution behavior of a mixture in which the groups can be identified.
This paper wae praaerrtadat the SPE 1985 Reservoirsimulation Symposiumheld in Dallas, Texaa, February 10-13, 1SS5.The material is subjectto corractiin by the author. Permission to mpy is restricted to an atwtrect of not more than 300 wade. Write SF'E, P.O. sax S3S836 Rkhafdam Te=s 750SMS36. Telex 7309SS SPE DAL: ABSTRACT fully implicit scheme. It is almost as 1ow as that A new fully implicit formulation for composi-required by an IMPES scheme. Llurrdl > Imuldbur-s iS pI-e>eIIbe U.~a~~e r~~~fi~o~~ing for pressure, saturations and phase compositions, the new formulation solves for pressure, INTRODUCTION overal1 concentrations and "K-values. This change Compositional reservoir simulators are imporof primary unknowns to be solved improves nunerical tant tools for predicting the performance of oi1stability by yielding a more diagonally dominant Jacobian.The use of K-values as primary unknowns recovery methods when oil and gas undergo vigorous interphase mass transfer during the recovery also allows the composition constraints to be process. These processes include (1) nitrogen solved separately from the other equations.The injection into a gas condensate or volatile oil solution of the constraint equations is very effireservoir during the primary production period, and cient because they can be reformulated as monotonic or enriched gas injection during the functions*. The primary unknowns are further clas-~;~a~~~recovery period.Recently, compositional sified into reduced-unknowns and pivotal-unknowns.simulators have become even more important as more The latters are eliminated from the mass consergas condensate and volatile oil reservoirs are vation equations using the fugacity equalities and discovered with deeper drilling and as more constraints.The pivotal-unknowns are selected enriched gas or C02 gas injection enhanced recoverY according to the sensitivity of the equations to projects prove successful. It is also being recogthe unknowns.This selection conforms to the nized that this type of model can be useful in partial pivoting strategy of Gaussian elimination studying "black-oil-type" reservoir with the crude and enhances numerical stability.Finally, a oil being characterized by two hydrocarbon componpartial solution method is introduced to eliminate entsl-2. This importance as well as usefulness has unnecessary calculations of those equations which motivated a continual development of more efficient have met the convergence criteria. and reliable compositional simulators. For a simple system, it is shown that the newThe development can be classified into two formulation results in a more diagonally dominant categories. The first category concerns the Jacobian matrix.Numerical experiments involving development of simple and reliable mathematical one dimensional multicontact-miscibile (MCM) andrepresentations of physical phenomena. Modelling immiscible problems, a two dimensional MCM problem of fluid phase behavior and properties3-8 interand a three dimensional MCM problem are conducted facial tensiong-lo, relat...
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