Liquid-phase Mutual Diffusion Coefficients for Heavy Oil + Light Hydrocarbon Mixtures

Abstract:

Liquid-phase mutual diffusion coefficients are a key parameter in reservoir simulation models related to both primary production and envisioned secondary recovery processes for heavy oil and bitumen. The measurement of liquid-phase mutual diffusion coefficients in bitumen and heavy oil + light hydrocarbon or gas mixtures present numerous experimental and data analysis challenges due to the viscosity and opacity of the mixtures, the variability of density, viscosity and mutual diffusion coefficient with composition, and the multi-phase nature of these mixtures. Data analysis challenges are particularly acute. For example, recently reported mutual diffusion coefficient values for liquid mixtures of bitumen + carbon dioxide vary over three orders of magnitude when different analysis methods are applied to the same experimental data. In this contribution, we illustrate the importance of measuring composition profiles within liquids as a function of time, as a basis for mutual diffusion coefficient computation, and for allowing explicitly for the variation of diffusion coefficient and liquid density with composition in the analysis of composition profile data. Such inclusions eliminate apparent temporal variations of mutual diffusion coefficients and yield values consistent with relevant theories and exogenous data sets. Liquid-phase mutual diffusion coefficients computed for the mixtures Athabasca Bitumen + pentane and Cold Lake Bitumen + heptane exemplify the experimental and data analysis approaches.     

Mass Transfer of CO2 Into Water and Surfactant Solutions

Abstract

The mass transfer of CO₂ into water and aqueous solutions of sodium dodecyl sulphate (SDS) is experimentally studied using a pressure, volume, temperature (PVT) cell at different initial pressures and a constant temperature (T = 25°C). It is observed that the transfer rate is initially much larger than expected from a diffusion process alone. The model equations describing the experiments are based on Fick's Law and Henry's Law. The experiments are interpreted in terms of two effective diffusion coefficients—one for the early-stages of the experiments and the other one for the later stages. The results show that at the early stages, the effective diffusion coefficients are one order of magnitude larger than the molecular diffusivity of CO₂ in water. Nevertheless, in the later stages the extracted diffusion coefficients are close to literature values. It is asserted that at the early stages, density-driven natural convection enhances the mass transfer. A similar mass transfer enhancement was observed for the mass transfer between a gaseous CO₂ rich phase with an oil (n-decane) phase. It is also found that at the experimental conditions studied addition of pure SDS does not have a significant effect on the mass transfer rate of CO₂ in water.     

The Effective Diffusion/Dispersion Coefficient in Vapor Extraction of Heavy Oil

Abstract

In this study, a new correlation for determination of effective diffusion/dispersion coefficients in the vapor extraction of heavy oil/bitumen (VAPEX) is introduced. This model takes into account the solvent concentration as well as the drainage height and permeability dependency of these coefficients. The concentration dependency in this model stems from the mixture viscosity changes, while the height dependency appears directly in the correlation. The correlation was obtained using the experimental results of the VAPEX experiments that were conducted with physical models of varying sizes and different permeability sand-packs. Estimation of a proper mass transfer coefficient has been a challenging issue for the analytical and numerical simulation of the VAPEX and other similar processes. Incorporating the effect of drainage height on dispersion with a concentration-dependent diffusivity model enables one to estimate the dispersion coefficient values involved in this process.     

The Determination of Effective Diffusivity Coefficients in a Solvent Gas Heavy Oil System for Methane

Abstract

In this investigation, an accurate high pressure and temperature diffusion setup was applied to measure the diffusion coefficients of methane in Iranian heavy oils in presence and absence of porous media by using the pressure-decay method. The solvent diffusivity in heavy oil was determined by both graphical and numerical methods. In addition, the effects of the porous medium and the temperature on the molecular diffusion coefficient of the solvent gas in the liquid phase were discussed and finally, using experimental data, a functionality dependence of molecular diffusivity on temperature and porous medium characteristics was proposed.     

Plasticizer migration in nitrocellulose-based propellants

Abstract

An “environmentally-friendly” technique for determining plasticizer concentration profiles in propellant sheets has been developed. The method was developed in response to a need for a quick, accurate means to study plasticizer migration in experimental gun propellents. Evidence of rapid migration between laminated sheets of nitrocellulose-based propellant containing different amounts of two nitrate ester plasticizers was obtained. An estimate of the diffusion coefficients for one of these plasticizers was also obtained.     

Gas permeability through poly(4-methyl-1-pentene) at temperatures above and below the glass transition point

Gas separation properties of polymer films based on semicrystalline poly(4-methyl-1-pentene) (PMP) with T _g = 30°C for permanent gases and some lower hydrocarbons have been experimentally studied in the temperature range of ?20 to 80°C. Experiments have been performed using the differential permeability technique involving the determination of the diffusion coefficient by the characteristic time and functional scaling-up methods. It has been shown that PMP as a biphasic system may be characterized by one diffusion coefficient that includes the contributions of diffusion in the amorphous and crystalline phases. It has also been shown that despite the glass transition (phase transition) at 30°C, the permeability coefficients of the test gases exponentially increase with gas temperature and the temperature dependence curves do not exhibit an inflection in the glass transition region. On the other hand, the Arrhenius plots of the diffusion coefficients show a bend over the entire glass transition range in PMP, with the activation energy of diffusion decreasing with an increase in temperature. This fact demonstrates the unusual, earlier unknown effect of increasing activation energy of diffusion E _D for gases below T _g.     

Multilateral Analysis of Pressure and Temperature Effects on Steam Methane Reforming Reaction

Abstract

Pressure and temperature effects on steam methane reforming (SMR) process in porous media and at equilibrium conditions of the reaction were investigated. The investigation was carried out by developing of a computer program to check the simultaneous effects of pressure and temperature on the extent of the reaction. Two methods for estimation of the effective diffusivity coefficients through porous catalysts were applied: (a) simplified method and (b) a new method based on more realistic conditions of the reaction. The results obtained based on this study would be useful for optimizing of pressure and temperature of SMR reaction.     

A New Method for Determining Bourgoyne and Young Penetration Rate Model Constants

Abstract

The objective of any drilling operation is to drill a well with the least possible cost and in the shortest time in compliance with safe operation. This objective is usually achieved by applying the drilling parameters in such a way that the fastest drilling rate would result. Several drilling penetration rate models have been proposed for estimation of penetration rate based on different drilling parameters. One of the most frequently used models for estimation of drilling penetration rate is the Bourgoyne and Young model. This model relates the penetration rate to several drilling parameters. There are eight unknown constants in this model. Bourgoyne and Young have proposed multiple regression analysis for obtaining these constants. Because the constant values obtained by multiple regression analysis are sometimes meaningless and are not in the recommended ranges, other methods for determining these coefficients are suggested. Some authors have used least squares data fitting methods and trust region approaches to obtain these coefficients. In this article, a new method is used for this purpose. A set of possible answers is chosen from the recommended bounds. Then the best fitted answers are selected and compared with a new set of possible answers. This trial is repeated until the desired answers are obtained. The results show the proficiency of the new methodology to determine constant coefficients of the Bourgoyne and Young penetration rate model.     

Experimental Evaluation of the Petrophysical Algorithm in an Integrated Flow Model

Abstract

An experimental apparatus was designed to simultaneously measure fluid flow rates and high-frequency (ultrasonic) elastic wave velocities. The measured fluid production and elastic wave velocity data were compared to integrated flow model (IFM) calculations. An IFM is a flow simulator with a petrophysical model that can calculate seismic attributes using reservoir and fluid properties. The petrophysical algorithm is an extension of Gassmann's equation that lets moduli depend on effective pressure, porosity, and clay fraction. A new set of correlation coefficients for the petrophysical algorithm was obtained by matching high-frequency measurements.     

Analytical Modeling of Gas Diffusivity Into Oil Through a Film of Water

Abstract

The authors aimed to determine diffusion coefficient of gas in oil when there is a water-blocking film between them. Dealing with this purpose, a new technique based on analytical modeling was developed to measure the diffusivity and solubility of gas into oil and water. The system that was described is solved analytically and numerically. The result of analytical solution is presented as different type curves, which are very simple to use. To generate data, a numerical scheme was employed. The determination of gas diffusivity and solubility emerged from matching concentration data with the type curves.     

Prediction of Diffusion Coefficients for Binary Gas System

A new formula has been developed to estimate diffusion coefficients for a binary system for some gases dependent on temperature, pressure, molecular weight, and a Pitzer acentric factor in a different range of temperatures. In this work, an introduction of the available observed data develops a new correlation for the effect of these parameters on the prediction of diffusion coefficients.     

Liquid-Phase Adsorption Kinetics of n-Paraffins on 5A Zeolite

Abstract

The adsorption kinetics of n-hexane from liquid-phase on 5A zeolite crystals, binderless pellets, powder with binder, and pellets with binder are investigated in order to develop the diffusion control mechanism. The adsorption kinetics of n-C₅–n-C₈ from liquid-phase are studied on binderless 5A zeolite pellets and the pellets containing binder. Adsorption rate of n-paraffins on binderless pellets is controlled by micropore diffusion while it is controlled by macropore diffusion on 5A zeolite pellets with binder. For the same adsorbate, the apparent diffusional time constants on the binderless pellets are about 6–11 times larger than those on others.     

THE COMPARISON OF NUMERICAL SOLUTION OF THREE KINDS OF MODELS OF THE INTRAPARTICLE EFFECTIVENESS FACTORS FOR MULTIPLE REACTIONS SYSTEM OF METHANOL SYNTHESIS IN THE PRECSENCE OF Cu-BASED CATALYST

Abstract

In this paper for methanol synthesis from the hydro-genation of CO and CO2 over surface poisoned or unpoi-soned Cu-based catalyst, three kinds of diffusion models for calculating the intraparticle effectiveness factors of the multiple reactions have been presented. They are one dimensional multi-components diffusion model, one demensional simplified multi-components diffusion model and one dimensional key-components diffusion model. Numerical solution of the intraparticle effectiveness factors solved by orthogonal collocation method have been obtained. Key-components diffusion model was available for calculating effectiveness factors only for the reactions over slightly poisoned catalyst. As poisoned fraction increases the deviation of effectiveness factors calculated from key-components diffusion model and multi-     

Diffusion and Convection With Chemical Reaction in a Three-Phase System

Abstract

The authors present a general theoretical analysis of the diffusion problem including chemical reaction for globules and liquid membrane in a 3-phase system. Volume-averaging transport equations are derived for globules and membrane with chemical reaction in both phases and for the continuous phase with diffusion and convection effects. With these equations, a one-concentration model to double emulsion system (globules and membrane) was derived, and for this the principle of local mass equilibrium was applied.     

Co-Mo/γ-Al2O3加氢脱硫催化剂的吸附扩散性能

用智能质量分析仪(Intelligent Gravimetric Analyser)测得了不同温度下异戊二烯(Isoprene)、戊烯-1(Pentene-1)及噻吩(Thiophene)在Co-Mo/γ-Al2O3选择性加氢脱硫催化剂上的吸附-脱附等温线及程序升温脱附曲线(TPD),并研究了三者在该催化剂上的扩散性能。结果表明,噻吩、异戊二烯、戊烯-1在Co-Mo/γ-Al2O3选择性加氢脱硫催化剂上的饱和吸附量依次降低;噻吩与该催化剂存在2种吸附作用,即物理吸附和化学吸附,化学吸附形成Co-Mo-S相,可有效地提高加氢脱硫催化剂的脱硫效果,而戊烯-1和异戊二烯在该催化剂上只存在1种弱吸附作用;3种吸附质中,戊烯-1相对扩散系数最大,噻吩和异戊二烯的相对扩散系数较小且相近。     

An inverse solution methodology for estimating the diffusion coefficient of gases in Athabasca bitumen from pressure-decay data

An inverse solution methodology is developed for the estimation of diffusion coefficient of gases in highly viscous, oil-sands bitumens from isothermal, pressure-decay measurements. The approach involves modeling the rate of change in pressure using the diffusion equation for the liquid phase coupled with a mass balance equation for the gas phase. The inverse solution framework is utilized to arrive at two graphical techniques for estimating the diffusion coefficient. Both techniques involve the determination of the slope of a straight line resulting from plotting the experimental data in accordance with the developed model. An advantage of the proposed techniques is that the diffusion coefficient is estimated directly, i.e. without making it an adjustable parameter. The novelty of the proposed method is in its simplicity as well as its ability to isolate portions of the pressure-decay data affected by experimental fluctuations. The effect of the initial pressure on the predicted diffusion coefficient and pressure-decay profile was also investigated. The diffusion coefficients of CO₂, CH₄, C₂H₆ and N₂ in Athabasca bitumen at 50–90 °C and about 8 MPa were estimated and compared with literature values.     

Dissolution study of BAMO/AMMO thermoplastic elastomer for the recycling and recovery of energetic materials

Abstract

This study involves the characterization and dissolution of a thermoplastic elastomer copolymer used as binder in the new generation of energetic materials. The thermoplastic binder is an oxetane based elastomer manufactured by Thiokol Corporation. Since the binder encapsulates other components in an energetic material formulation, its controlled dissolution is crucial to the recovery and recycle of all the energetic material ingredients. The polymeric binder was found to be highly soluble in ethyl acetate and THF. The dissolution rate data obtained under well defined flow dynamics was satisfactorily correlated with the film model. External mass transfer resistance was found to be generally important but became negligible for Reynolds numbers above 6.0×10⁴. The mass transfer coefficients calculated on the basis of the film model were found to be an Arrhenius function of temperature. The activation energy for the dissolution rates was estimated to be 4.8 kcal/mol.     

A Mathematical Model and Solution for Mass Transfer and Diffusion After a Polymer Flood with Flow Channel

Abstract

Reservoirs in eastern China are now characterized by serious flow channels due to long-term waterflooding, and thus the general one-dimensional mass transfer and diffusion equation and its analytical model are no longer applicable because no transversal dispersion was considered. For reservoirs with breakthrough flow channels, the physical model is abstracted and a mathematical model for in-layer mass transfer and diffusion with longitudinal and transversal dispersion considered is also established. Analytical and numerical solutions are obtained. The analytical and mathematical solutions help us to deepen the understanding of the physical process of mass transfer and diffusion.     

Diffusion Coefficient of a Binary Liquid System

Abstract

A generalized diffusion coefficient correlation for a binary system of liquids has been developed to represent the data for a wide range of temperatures. Detailed analysis shows that the proposed correlation fits the experimental measurements of diffusivity with the corresponding calculated values with an acceptable percentage error.