A New Method for Gas Effective Diffusion Coefficient Measurement in Water-Saturated Porous Rocks under High Pressures

Li, Zhaowen; Dong, Mingzhe; Li, Shuliang; Dai, Liming

doi:10.1615/jpormedia.v9.i5.50

Cited by 29 publications

(54 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Diffusion is a spontaneously dispersing process of molecules or ions [23], which is caused by the concentration difference in solutions or dispersions. The quantitative description of the rate of the diffusion process is usually expressed by the diffusion coefficient [24][25][26][27]. There have been several mass transfer process of CO2 into the oil-saturated low-permeable cores.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Oil Properties on the Supercritical CO2 Diffusion Coefficient under Tight Reservoir Conditions

Zhang

Qiao

et al. 2018

Energies

View full text Add to dashboard Cite

In this paper, a generalized methodology has been developed to determine the diffusion coefficient of supercritical CO 2 in cores that are saturated with different oil samples, under reservoir conditions. In theory, a mathematical model that combines Fick's diffusion equation and the Peng-Robinson equation of state has been established to describe the mass transfer process. In experiments, the pressure decay method has been employed, and the CO 2 diffusion coefficient can be determined once the experimental data match the computational result of the theoretical model. Six oil samples with different compositions (oil samples A to F) are introduced in this study, and the results show that the supercritical CO 2 diffusion coefficient decreases gradually from oil samples A to F. The changing properties of oil can account for the decrease in the CO 2 diffusion coefficient in two aspects. First, the increasing viscosity of oil slows down the speed of the mass transfer process. Second, the increase in the proportion of heavy components in oil enlarges the mass transfer resistance. According to the results of this work, a lower viscosity and lighter components of oil can facilitate the mass transfer process.Energies 2018, 11, 1495 2 of 20 methods for the quantitative determination of the gas (N 2 , CO 2 , CH 4 [28], C 2 H 6 , C 3 H 8 , or a mixture gas) diffusion coefficient in crude oil. These methods include the pressure decay method, X-ray computer-assisted tomography (CAT) method, magnetic resonance imaging (MRI) method [29,30], dynamic drop volume analysis (DPDVA), and pore-scale network modeling method. All of these methods have advantages and flaws:Direct testing method. Hill and Lacey [31] tested the diffusion coefficient of CH 4 in isopentane with a constant pressure method in a Pressure-Volume-Temperature (PVT) system. Sigmund [32] also used this method to study the binary dense gas diffusion coefficients under reservoir conditions. Islas-Juarez et al. [33] set up an experimental device to determine the effective diffusion coefficient of N 2 in a sandpack model. They devised a special setting to sample crude oil that was dissolved with N 2 in their porous model. The samples were then analyzed by gas chromatograph, and the gas concentration in the oil phase was determined. The corresponding diffusion coefficient was determined by matching the mathematical diffusion model with the experimentally measured concentration curve. The main shortcomings of the direct testing method for the solvent diffusion coefficient are that it is both time and labor consuming, which results in an expensive process.Pressure decay method. Riazi [34] proposed a technique known as the pressure decay method based on the fact that the pressure of the gas phase in a closed diffusion cell decreases with the migration of the gas phase into the liquid phase. One of the remarkable features of this method is that it does not require costly component measurements. In the following two decades, many scholars adopted this method to test the diffus...

show abstract

Section: Introductionmentioning

confidence: 99%

The Effect of Oil Properties on the Supercritical CO2 Diffusion Coefficient under Tight Reservoir Conditions

Zhang

Qiao

et al. 2018

Energies

View full text Add to dashboard Cite

show abstract

“…We have shown earlier that the equilibrium model is a special case of the quasi‐equilibrium model with large values of λ. Although the equilibrium model is just an approximate model to describe the real processes of gas diffusion in liquid, it is still one of the most widely used pressure‐pulse decay (PPD) models . There are two reasons for this: (1) simplicity of data analysis; (2) when the pressure change of gas phase is very small ( λ → ∞), the model is precise enough to approximate the quasi‐equilibrium model .…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the indirect methods are preferable in engineering applications. The indirect methods are composed of the pressure‐decay method, the electromagnetic method, the PH method, density method, the swelling of a pendant droplet method, and visualized dye method, among others. The indirect physical data, such as pressure change and PH distribution, are used to measure the diffusion coefficient of the liquid/gas mixture.…”

Section: Introductionmentioning

confidence: 99%

“…The diffusion coefficient is determined by fitting the corresponding diffusion mathematical model with the pressure‐decay data vs. time. The method has been widely used to study diffusion of gases in heavy oil and bitumen and diffusion of CO 2 in water . If the pressure‐decay technique is used to measure the mass transfer of CO 2 in water, the density‐driven convection needs to be considered …”

Section: Introductionmentioning

confidence: 99%

“…The equilibrium model considers that the concentration on gas/liquid interface is constant and always equal to the equilibrium concentration. This model has been widely used to measure diffusion coefficient . The limitation of this model is that the decay in pressure of the gas phase should be very small; otherwise, error will occur when the model is used to analyze pressure‐decay data.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An analytical method of estimating diffusion coefficients of gases in liquids from pressure decay tests

2018

Self Cite

View full text Add to dashboard Cite

We present an exact solution of quasi-equilibrium model, based on pressure decay technique, to measure diffusion coefficient. The results of the quasi-equilibrium model are compared with the traditional equilibrium model and it was found that the latter is only a special case of former one. We provide new approximate solution to estimate diffusion coefficient that is more convenient to use, compared with the previously reported approaches. It also reveals that our solution is capable of taking into account greater portion of the collected pressure decay test data and is more accurate. Based on the developed solution, estimation approaches, including linear method and exponential method, are presented and applied to analyze synthetic and experimental pressure-decay data. The quasi-equilibrium model is also compared with the traditional equilibrium model. The results reveal that analysis of the test data using equilibrium model may introduce large error in estimation of diffusion coefficient.

show abstract

Predicted Dependence of Gas—Liquid Diffusion Coefficient on Capillary Pressure in Porous Media

Guo

et al. 2017

Chem Technol Fuels Oils

View full text Add to dashboard Cite

A New Method for Gas Effective Diffusion Coefficient Measurement in Water-Saturated Porous Rocks under High Pressures

Cited by 29 publications

References 0 publications

The Effect of Oil Properties on the Supercritical CO2 Diffusion Coefficient under Tight Reservoir Conditions

The Effect of Oil Properties on the Supercritical CO2 Diffusion Coefficient under Tight Reservoir Conditions

An analytical method of estimating diffusion coefficients of gases in liquids from pressure decay tests

Predicted Dependence of Gas—Liquid Diffusion Coefficient on Capillary Pressure in Porous Media

Contact Info

Product

Resources

About