Purpose: The purpose of this paper is to investigate oil-gas slug formation in horizontal straight pipe and its associated pressure gradient, slug liquid holdup and slug frequency. Design/methodology/approach: The abrupt change in gas/liquid velocities, which causes transition of flow patterns, was analyzed using incompressible volume of fluid method to capture the dynamic gas-liquid interface. The validity of present model and its methodology was validated using Baker’s flow regime chart for 3.15 inches diameter horizontal pipe and with existing experimental data to ensure its correctness. Findings: The present paper proposes simplified correlations for liquid holdup and slug frequency by comparison with numerous existing models. The paper also identified correlations that can be used in operational oil and gas industry and several outlier models that may not be applicable. Research limitations/implications: The correlation may be limited to the range of material properties used in this paper. Practical implications: Numerically derived liquid holdup and holdup frequency agreed reasonably with the experimentally derived correlations. Social implications: The models could be used to design pipeline and piping systems for oil and gas production. Originality/value: The paper simulated all the seven flow regimes with superior results compared to existing methodology. New correlations derived numerically are compared to published experimental correlations to understand the difference between models.

The mathematical formulation of a three-phase, three-dimensional fluid flow and rock deformation in fractured reservoirs is presented in this paper. The present formulation accounts for the significant influence of coupling between the fluid flow and solid deformation, an aspect usually ignored in the reservoir simulation literature. A Galerkin-based finite element method is applied to discretise the governing equations in space and a finite difference scheme is used to march the solution in time. The final set of equations, which contain the additional cross coupling terms as compared to similar existing models, are highly nonlinear and the elements of the coefficient matrices are updated implicitly during each iteration in terms of the independent variables. A field scale example is employed as an alpha case to test the validity and robustness of the currently formulation and numerical scheme. The results illustrate a significantly different behavior for the case of a reservoir where the impact of coupling is also considered. Dans cet article, les auteurs, s'appuyant sur la théorie de la double porosité, développent une formulation mathématique tridimensionnelle des écoulements de fluides triphasiques et de la déformation de la roche pour des réservoirs fracturés. La formulation actuelle, qui recouvre à la fois les équations d'équilibre mécanique et les équations de conservation de la masse dans le cas d'écoulements multiphasiques, rend compte de l'influence significative du couplage entre écoulements fluides et déformations solides, généralement non pris en compte ou négligés dans les publications traitant de la simulation des réservoirs. Une méthode par élément fini de type Galerkin est employée pour discrétiser les équations principales dans l'espace et un schéma en différences finies en temps est utilisé pour déterminer l'évolution au cours du temps. Comparé à des modèles similaires existants, celui-ci identifie non seulement la déformation interne du squelette rocheux sous l'effet de la pression différentielle entre le milieu poreux et le milieu fissuré, mais les équations de conservation de masse qui en résultent sont entièrement couplées. À titre de comparaison, un exemple à l'échelle d'un réservoir sert de test alpha de la robustesse de la méthodologie adoptée. Les résultats indiquent que le comportement du réservoir est sensiblement différent lorsque l'effet du couplage est représenté.