Summary Wax precipitation is often studied using stock-tank oil. However, may be very different in well-tubing and production facilities because of the effects pressure composition. For example, cloudpoint temperature decrease as much 15 K from atmospheric to a saturation 100 bar mostly solubility light hydrocarbons into oil (i.e. composition effect). In this study, (CPT) at live-oil conditions amount precipitated wax stock-tank-oil are provided for four crudes. one crudes, effect dilution...

Summary A thermodynamic framework is proposed to describe the structure of asphaltene micelles and precipitation in crude. The micelle assumed consist an core surrounded by a solvated shell. shell contains both resin all other species except asphaltenes. theoretical consists standard Gibbs free energy micellar formation energies ofthe petroleum liquid precipitated phase. modeled as sum various contributions including association between molecules core, deformation micelle, adsorption onto...

CO2 injection into an oil reservoir at low temperature can lead to the formation of three hydrocarbon phases. Key challenges persist in development phase equilibrium calculations for three-phase hydrocarbon–CO2 systems. One challenge is identification a third via stability testing two-phase mixture. Stability requires initial estimates ratios (K-values). Existing methods estimating K-values behavior are unable detect whole region. In addition, many K-value redundant, wherein convergence same...

Summary Given pressure, temperature, and composition of a fluid, one desires to determine whether the single phase state is stable. This problem is, in principle, much simpler than phase-behavior calculations. For certain applications, such as compositional-reservoir modeling, stability testing can be most important item for efficient In this paper, we use tangent-plane-distance (TPD) reduced space perform analysis testing. The results reveal that there are major advantages space. One...

Abstract Aromatic solvents and oil‐soluble amphiphiles are recognized as asphaltene precipitation inhibitors in oil production transportation. In the absence of model describing effect these on from crudes, proposed is a thermodynamic micellization explaining inhibition mechanism for both aromatic amphiphiles. The shows that concentrated micellar shell, interfacial tension between core shell reduced micelles becomes stabler. A crude, mixed with small amount an amphiphile, achieves high...

Summary The production of shale oil and gas has experienced a substantial rise over the past decades. However, traditional numerical simulators have shown significant inconsistencies in forecasting ultimate recovery rates, primarily due to widespread nanoscale pores reservoirs, which induce pronounced capillary pressure (Pc) between liquid phases, leading deviations phase behavior. Besides, numerous convergence problems formulation issues are reported for Gibbs free energy-based equilibrium...

Summary Volume-based phase equilibrium calculations (PECs) are gaining increasing attention because the traditional Gibbs free-energy-based PECs encounter various convergence issues when capillary pressure is introduced. However, conventional successive substitution iteration (SSI) inapplicable without modification to volume-based PECs, thus necessitating a robust and efficient algorithm. In this study, we developed unified trust region (TR) Newton-based algorithmic framework for at...

Dimethyl ether (DME) has emerged as a promising additive in CO2-enhanced oil recovery (EOR), and the minimum miscibility pressure (MMP) is pivotal for flooding strategies. However, research on DME's impact MMP limited. This study undertakes comprehensive investigation into effects of DME gas–oil during CO2 flooding, considering water-free water-saturated scenarios. First, two-phase multiple-mixing-cell method (MMC) with rapid estimation technique adopted to analyze influence concentration...

Abstract In shale reservoirs, the prevalent tight porosity induces significant capillary pressure (Pc), markedly altering fluid behavior from bulk conditions. Numerical convergence and methodologicalissues were reported for phase equilibrium calculations (PECs) incorporating Pc in nano-pore media. Thus, it is imperative to develop an efficient robust PECs algorithm that includes accuratelysimulate oil gas production reservoirs. We developed two independent artificial neural network...

Summary Asphaltene precipitation from reservoir crudes has been modeled using liquid-liquid equilibrium; the precipitated heavy phase is assumed to be in liquid state and consist of only asphaltene resin. The light monomers all components micelles. A thermody-namic micellization model Peng-Robinson equation (EOS) description fully describe ther-modynamic equilibrium state. From direct minimization Gibbs free energy system, composition amount each phases are calculated. above used calculate...

Summary In Part I of our study, stability analysis testing in the reduced space was formulated, and its robustness efficiency comparison to conventional approach explored. this paper, we present formulations including, first, direct solution nonlinear equations, second, minimization Gibbs free energy for two-phase flash computations space. We use various algorithms including successive substitution (SS), Newton's method, globally convergent modifications method (line searches trust region),...

Summary The computational problems in reservoir fluid systems are mainly the critical region and liquid-liquid (LL), vapor-liquid-liquid (VLL), higher-phase equilibria. conventional methods to perform phase-equilibrium calculations with equality of chemical potentials cannot guarantee a correct solution. In this study, we propose simple method calculate equilibrium state by direct minimization Gibbs free energy system at constant temperature pressure. We use simulated annealing (SA)...

Thermal compositional simulation requires phase-equilibrium calculations for at least three fluid phases. The use of precomputed equilibrium ratios (K-values) has long been justified on the basis efficiency. However, this method may not appropriately represent thermal recovery mechanisms. An equation state (EOS) approach is more rigorous, though prohibitively costly. In processes injection steam results in hydrocarbon–water interactions elevated temperatures. Representation phase behavior...

Abstract The Phase Equilibrium Computations (PEC) associated with compositional flow simulation include: (1) Phase-Stability Analysis (PSA) of single-phase cells, and (2) Two-Phase Flash (TPF) for cells that change from one to two phases over a Newton iteration. For multi-contact miscible displacements, the PEC cost increases dramatically number components, highly detailed models, can become most time consuming part simulation. In this work, we integrated Reduced-Variables (RV) method (Pan...

Summary CO2 injection into an oil reservoir at low temperatures (less than 120 °F) can form three hydrocarbon phases—a vapor phase, oil-rich liquid, and a CO2-rich liquid phase. Most available simulators cannot handle three-hydrocarbon-phase flash, the use of two-phase flash may cause significant numerical instability. The issue has been recognized in industry for long time. Studies to include compositional simulations exist literature. However, this approach results substantial increases...