Petroleum Engineering – Reservoir
Mehdi Bahari Moghaddam; Seyyed Alireza Kamani
Abstract
An essential transport characteristic that links a substance's molar (mass) flux to its concentration gradient is the molecular diffusion coefficient. For modeling and performance forecasting of solvent-aided recovery processes of heavy oils such as VAPEX and SAGD; a reliable and accurate estimation ...
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An essential transport characteristic that links a substance's molar (mass) flux to its concentration gradient is the molecular diffusion coefficient. For modeling and performance forecasting of solvent-aided recovery processes of heavy oils such as VAPEX and SAGD; a reliable and accurate estimation of the molecular diffusion coefficient is a crucial input. Despite the importance of this parameter, there is no approved way to measure it, especially in systems with heavy oil and gaseous solvents that have limited solubility. This can be as a result of the intricacy of experimental measures and the challenge of analyzing experimental data. There are two direct and indirect methods for measuring the diffusion coefficient, the direct method has not been addressed because it is expensive and time-consuming. Indirect methods include Constant-Volume Methods (Pressure Decay), Constant-Pressure, Refractive Index, Nuclear Magnetic Resonance (NMR), X-ray Computer-Assisted Tomography (CAT), Pendent drop and Microfluidics. The advantage and disadvantages of these experimental methods established for diffusivity measurements of the gaseous solvent in heavy oil systems are discussed in this article. According to the investigations carried out in this study, the Constant-Volume Methods (Pressure Decay) with the least error percentage (1.05%) was chosen as the best method for measuring the diffusion coefficient. The diffusion coefficient of light and heavy oil was compared, and light oil has a higher diffusion coefficient.
Petroleum Engineering
Mehdi Bahari Moghaddam; Mostafa Fathalizade
Abstract
Enhanced oil recovery (EOR) is a vital part of the process of oil production from sandstone and carbonate reservoirs. Maintaining and increasing oil production from many fields require proper selection, design, and implementation of EOR methods. The selection of EOR methods for specific reservoir conditions ...
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Enhanced oil recovery (EOR) is a vital part of the process of oil production from sandstone and carbonate reservoirs. Maintaining and increasing oil production from many fields require proper selection, design, and implementation of EOR methods. The selection of EOR methods for specific reservoir conditions is one of the most difficult tasks for oil and gas companies. Screening of different EOR techniques considering previous experiences from the methods applied in other fields is a first step in the recommendation of any costly EOR operations. In this paper, EORgui software was utilized to screen eight enhanced oil recovery methods in one of Iran’s offshore sandstone oil fields. The reservoir is composed of two sections with different fluid properties, namely API, viscosity, and oil composition, but relatively homogeneous rock properties and high permeability (1500 mD). The results show that polymer flooding is technically the most suitable enhanced oil recovery method in the upper zone of the reservoir with a high percentage matching score of 90%, and immiscible gas injection with a matching score of 83% is ranked second. For the lower part of the reservoir containing a fluid with much higher viscosity, immiscible gas injection (83% matching) can be recommended. Furthermore, polymer flooding predictive module (PFPM) was utilized to investigate the impact of polymer concentration on oil recovery performance of the upper part with an ultimate recovery of about 40% at the optimum concentration.