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Etude de l'effet de l'addition de gaz sur l'équilibre de phases en mélanges pétroliers dans des conditions de haute pression et haute température.

Abstract : Phase behavior of reservoir fluids is a crucial information for an efficient production development project. Depending on fluid characteristics, their phase behavior can vary from simple to complex multiphasic equilibria. Moreover, multiphasic equilibria may be encountered by natural occurrence under reservoir conditions or induced during production operations. Recently, complex phase behavior has been reported for Brazilian Pre-Salt crude oils, especially for medium crude oil fluids associated with high gas oil ratios. Specifically, evidence of complex liquid – liquid equilibria have been reported at high pressure and high temperature conditions. However, the study and detection of this equilibrium have been limited by the crude oil characteristics, high opacity, and low phase segregation, that limits conventional PVT laboratorial analysis. For that reason, it is proposed in this work a systematic study of phase behavior of Pre-Salt crude oils mixed with gases at high proportion. Phase transitions were investigated by a combination of PVT techniques providing visualization and detection of phase transitions in opaque fluids under high pressure. Through these studies, non-typical phase transitions were detected for systems involving high methane content, when analyzed using conventional PVT techniques (near-infrared light scattering and high-pressure microscopy). Results show the formation of a high dispersed second liquid phase, no fractal, with fast redissolution at high pressure. Bulk fluid analyses were also made by intermediate of a new full visual PVT technique, using a short-wave infrared fluid imaging designed for opaque crude oil evaluation. This test confirms a second dense liquid phase that can be formed when crude oil is mixed at a high gas oil ratio, especially with methane. Thermodynamic modelling and solubility analysis suggest that this second phase formed could be a heavy and aromatic dominated phase, but its behavior is far from typical asphaltenes. Based on the formed second phase characteristics, a wide biphasic liquid – liquid region is then identified for mixtures of crude oil and gas, especially for low molecular weight gases at high gas oil proportion.
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Submitted on : Friday, September 10, 2021 - 9:51:10 AM
Last modification on : Saturday, September 11, 2021 - 3:40:56 AM

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José Francisco Romero Yanes. Etude de l'effet de l'addition de gaz sur l'équilibre de phases en mélanges pétroliers dans des conditions de haute pression et haute température.. Génie des procédés. Université de Pau et des Pays de l'Adour; Universidade federal do Ceará, 2021. Français. ⟨NNT : 2021PAUU3011⟩. ⟨tel-03340202⟩

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