"Laboratory Methods for Calculating Gas Diffusion in Crude Oil"

Molecular penetration plays a crucial role in enhancing oil recovery through gas injection into reservoirs. The concentration gradient between the injected gas and the reservoir oil drives mass transfer between the two phases, eventually forming a miscible front over time. This interaction improves oil recovery, particularly by mobilizing oil trapped on the walls of the porous reservoir rock. Accurately determining the gas molecular diffusion coefficient in oil is vital for optimizing gas injection processes, making it a key focus in reservoir studies.Direct methods for measuring molecular diffusion coefficients, although accurate, are expensive and time-consuming. To address these challenges, alternative techniques have been developed that do not require detailed fluid composition analysis. These methods often rely on monitoring easily measurable parameters, such as changes in fluid volume, variations in the gas-oil interface height, pressure drop rates in a PVT cell, or gas injection flow rates under constant pressure and volume conditions. However, one major limitation of some traditional methods is their inability to distinguish between different stages of gas permeation, which can lead to errors in calculating diffusion coefficients based on experimental data.This study focuses on indirect and simplified methods that require minimal equipment for analyzing fluid properties and real-time monitoring. These methods avoid the use of in situ monitoring tools like HMR, Laser, or X-Ray devices, instead emphasizing the direct measurement of parameters influenced by molecular diffusion. By streamlining the process and reducing reliance on complex tools, the proposed methods enable the calculation of diffusion coefficients more efficiently and cost-effectively. Such advancements not only reduce experimental complexity but also enhance the accuracy of results, addressing key limitations of previous approaches and paving the way for more practical applications in oil recovery optimization.

کلیدواژه ها:

Molecular diffusion coefficient ، direct and indirect methods ، concentration gradient ، pressure-volume-temperature experiments