Estimating Diffusion Coefficients of Shale Oil, Gas, and Condensate with Nano-Confinement Effect
- Fengshuang Du (Virginia Polytechnic Institute and State University) | Bahareh Nojabaei (Virginia Polytechnic Institute and State University)
- Document ID
- Society of Petroleum Engineers
- SPE Eastern Regional Meeting, 15-17 October, Charleston, West Virginia, USA
- Publication Date
- Document Type
- Conference Paper
- 2019. Society of Petroleum Engineers
- diffusion coefficient, porous media, nano-confinement effect, critical property shifts, shale type fluids
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Molecular diffusion plays an important role in oil and gas migration and transport in tight shale formations. However, there are insufficient reference data in the literature to specify the diffusion coefficients within a porous media. This study aims at calculating diffusion coefficients of shale gas, shale condensate, and shale oil at reservoir conditions with CO2 injection for EOR/EGR. The large nano-confinement effects including large gas-oil capillary pressure and critical property shifts on diffusion coefficient are examined. An effective diffusion coefficient that describes the diffusion behavior in a tight porous solid is estimated by using tortuosity-porosity relations as well as the measured shale tortuosity from 3D imaging techniques. The results indicated that nano - confinement could affect the diffusion behavior through altering the phase properties, such as phase compositions and densities. Compared to bulk phase diffusivity, the effective diffusion coefficient in a porous shale rock is reduce by 102 to 104 times as porosity decreases from 0.1 to 0.03.
|File Size||1 MB||Number of Pages||20|
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