Shauheen Etminan - Academia.edu (original) (raw)

Uploads

Papers by Shauheen Etminan

Accurate estimation of molecular diffusion coefficient is necessary for the design and modeling o... more Accurate estimation of molecular diffusion coefficient is necessary for the design and modeling of solvent-assisted recovery techniques for exploitation of heavy oil and bitumen resources. Several studies on molecular diffusion measurement have been conducted using various pure gaseous solvents but there are very few diffusivity measurements available for the propane-bitumen system. The scarcity of these data is due to the complexities arising in the modeling of dissolution of propane in bitumen. These include high solubility of propane in bitumen and subsequently, dramatic volume change of the diluted oil, drastic reduction of bitumen viscosity during dilution and the possibility of asphaltene precipitation. In this work, a rigorous numerical model is developed to model the diffusivity of propane in bitumen based on real data. This model accounts for bitumen solution density change (swelling) as a result of dilution. A front-tracking moving boundary algorithm and numerical procedure is proposed which accounts for volume change of each grid at each time step. Those grids which experience diffusive flux, change sizes based on non-ideal mixing data available from measurement of solution density versus concentration. Finally, the Levenberg-Marquartd method was applied to estimate the propane diffusion coefficient based on laboratory measured gas-oil interface movement. A constant-pressure diffusion measurement experimental technique was used to measure mass of gas dissolved and solution height change in a propane-bitumen diffusion experiment at 413.7kPa (60 psia) and 827 kPa (120 psia) both in 24°C. The experimental results show that the "no-swelling" simplifying assumption often used in diffusion measurement modeling studies, cannot be generalized to all gaseous solvents because based on our experiments, the bitumen solution volume can be increased by 50% due to propane dissolution. The estimated diffusion coefficient is compared with the results of other mathematical techniques available in the literature. It is shown that the no-swelling simplifying assumption used in unidirectional modeling of gas diffusion in bitumen leads to estimation of erroneous parameters when propane is the gas and oil density and oil volume change is neglected.

ABSTRACT Not finding what you're looking for? Some of the OnePetro partner societies have... more ABSTRACT Not finding what you're looking for? Some of the OnePetro partner societies have developed subject- specific wikis that may help. PetroWiki PetroWiki was created from the seven volume Petroleum Engineering Handbook (PEH) published by the Society of Petroleum Engineers (SPE). The SEG Wiki The SEG Wiki is a useful collection of information for working geophysicists, educators, and students in the field of geophysics. The initial content has been derived from : Robert E. Sheriff's Encyclopedic Dictionary of Applied Geophysics, fourth edition.

Czechoslovak Journal of Physics, 1993

The concentration dependent diffusion coefficient of nitrogen in expanded austenite was determine... more The concentration dependent diffusion coefficient of nitrogen in expanded austenite was determined from the rate of retracting nitrogen from thin initially N-saturated coupons. Nitrogen saturated homogeneous foils of expanded austenite were obtained by nitriding AISI 304 and AISI 316 in pure ammonia at 693 K and 718 K. Denitriding experiments were performed by equilibrating the foils with a successively lower nitrogen activity, as imposed by a gas mixture of ammonia and hydrogen. The concentration depen-dent diffusion coefficient of nitrogen in expanded austenite was approximated in the composition range where nitrogen can be extracted by hydrogen gas at the diffusion temperature. Numerical simulation of the denitriding experiments shows that the thus determined concentration dependent diffusion coefficients are an accurate approximation of the actual diffusivity of nitrogen in expanded austenite.

Energy & Fuels, 2010

A modified pressure decay method has been designed and tested for more reliable measurements of m... more A modified pressure decay method has been designed and tested for more reliable measurements of molecular diffusion coefficients of gases into liquids. Unlike the conventional pressure decay method, the experimental setup has been designed such that the interface pressure and consequently the dissolved gas concentration at the interface are kept constant. This is accomplished by continuously injecting the required amount of gas into the gas cap from a secondary supply cell to maintain the pressure constant at the gas-liquid interface. The pressure decay is measured in the supply cell. The advantage of the new technique is that, assuming the diffusion coefficient to be constant, a simple analysis allows determination of the equilibrium concentration and diffusion coefficient.

The objective of this work was to study the effect of connate water in the progression of the Vap... more The objective of this work was to study the effect of connate water in the progression of the Vapor Extraction (VAPEX) process for heavy oil recovery. A large fraction of the physical model tests of the VAPEX process reported in the literature have been conducted without any connate water in the system. The absence of connate water was rationalized by suggesting that it has little or no influence on relative permeability of oil and since the vaporized solvent does not dissolve in water, there is no effect of water on the mass transfer process. We have evaluated the effect of connate water on VAPEX performance using physical model experiments carried out in a visual model, with different connate water saturations. Butane was used as the solvent and fine Ottawa sand was used for packing the model to obtain permeability and capillary pressure values comparable to the field conditions. In addition to the visual observations of the size and shape of the vapor chamber, the rates of oil an...

Canadian Unconventional Resources and International Petroleum Conference, 2010

Page 1. CSUG/SPE 138191 Mass Diffusion Parameters in Presence of Interface Resistance in Gas-Bitu... more Page 1. CSUG/SPE 138191 Mass Diffusion Parameters in Presence of Interface Resistance in Gas-Bitumen Systems S. Reza Etminan, M. Pooladi-Darvish, B. Maini, Z. Chen, SPE, University of Calgary Copyright 2010, Society ...

ABSTRACT Total gas storage capacity in many shale gas reservoirs arises from three sources: compr... more ABSTRACT Total gas storage capacity in many shale gas reservoirs arises from three sources: compressed gas in the micro- and nano-scale pores, adsorbed gas on the inner surfaces of pores in kerogen—the main constituent of organic materials in shale—and dissolved gas molecules in kerogen. The storage capacity of and transport processes for each of these three sources of gas are different, and accordingly, appropriate models and production strategies should be developed on the basis of actual physics. Of great relevance to field development and management is knowing the contribution of each source to daily production and ultimate gas recovery. A valuable body of literature has addressed the first two sources, but the last source has not been studied in detail. We developed a technique to measure the gas capacity from each of the above-mentioned three sources simultaneously, in a small piece of a shale sample, through batch pressure decay experiments. Temporal pressure decay is recorded using a quartz high-resolution pressure transducer for several days. The pressure-decline curve shows distinctive slope changes representing different storage processes. Pressure decline at the earliest time represents gas migration into the micro- and nano-pores. This is followed by a change in the slope of the pressure decline in an intermediate time, representing gas adsorption onto the inner surface of kerogen pores. At the later time, the slope of the pressure decline changes again, representing gas diffusion into kerogen. In the samples we tested, we found that dissolved gas in kerogen can contribute about 22% of the total gas-in-place. Assuming that gas molecules diffuse into the walls of the pores in kerogen, we used a Fickian diffusion model and a parameter-estimation technique to estimate the gas molecular diffusion coefficient in kerogen. We measured the diffusion coefficient of methane in amorphous kerogen as being on the order of 10− 20 m2/s.

h i g h l i g h t s " Dilute dissolution of gases into heavy oil was modeled accounting for 3 par... more h i g h l i g h t s " Dilute dissolution of gases into heavy oil was modeled accounting for 3 parameters. " The unknown parameters were diffusion and mass transfer coefficients and solubility. " It models both equilibrium and non-equilibrium interface boundary conditions. " This model uses the pressure decay data directly for the parameter estimation. " Determination of k value does not necessarily imply for physical interface resistance. " Correct modeling of interface physics leads to accurate estimation of the parameters.

Journal of Canadian Petroleum Technology, 2008

A large fraction of the physical model tests of the VAPEX process reported in the literature have... more A large fraction of the physical model tests of the VAPEX process reported in the literature have been conducted without any connate water in the system. The absence of connate water was rationalized by suggesting that it has little or no influence on relative permeability of oil and since the vapourized solvent does not dissolve in water, there is no effect of water on the mass transfer process. However, this ignores the possible contribution of oil spreading at the gas-water interface to the mass transfer and the contribution of film drainage to oil relative permeability at low oil saturation. We have evaluated the effect of connate water on VAPEX performance using physical model experiments carried out in a visual model with different connate water saturations. Butane was used as the solvent and Ottawa sand was used for packing the model to obtain permeability and capillary pressure values comparable to field conditions. In addition to the visual observations of the size and shap...

Czechoslovak Journal of Physics, 1993

Energy & Fuels, 2010

Canadian Unconventional Resources and International Petroleum Conference, 2010

Journal of Canadian Petroleum Technology, 2008