Mecánica del desplazamiento y estabilidad del petróleo espumoso durante la recuperación secundaria de petróleo pesado usando metano y aire

A pesar de que se llevaron a cabo muchas investigaciones experimentales sobre el flujo de petróleo espumoso, los fundamentos teóricos de su desempeño aún no son lo suficientemente convincentes, y los mecanismos para los procesos dinámicos y la estabilidad aún no se comprenden completamente. Con el fin de desarrollar una comprensión mecanicista del flujo de petróleo espumoso en un medio poroso, se consideraron experimentos de laboratorio bajo dos escenarios de inyección utilizando metano y aire como gases de inyección. Se realizaron experimentos de inyección en un esquema CSI de un solo pozo para comprender la generación de petróleo espumoso en reservorios post-CHOPS. Se consideró que el esquema CSI de múltiples pozos para comprender la generación de petróleo espumoso en reservorios delgados de petróleo pesado. Para ambos arreglos, se realizaron diferentes estrategias de inyección, tales como inyección alterna e inyección simultánea de gas. Se ha observado que el uso del aire ahorra el uso de metano hasta un 26 % y un 51 % en esquemas de inyección de un solo pozo y de pozos múltiple, respectivamente.Heavy oil and extra-heavy oil (natural bitumen and oil sands) resources represent 70% of the global petroleum reserves and are mostly found in shallow reservoirs with thin pay zones formed by unconsolidated sands. Thermal recovery methods are recognized for being the most efficient; yet, these methods face environmental challenges due to the high emissions of carbon dioxide generated by high energy demands, leading to high operational costs. Therefore, non-thermal recovery methods have attracted special attention from both industry and academia. Foamy oil is the terminology commonly accepted to describe an atypical behavior associated with heavy oil flow formed as a response to pressure depletion. The cyclic solvent injection (CSI) technology is a solvent-based non-thermal process that has gained interest and is considered as an effective technique for increasing the recovery factor either as a follow-up process to the cold heavy oil production with sand (CHOPS) or for thin heavy oil reservoirs. Notwithstanding that many experimental investigations on foamy oil flow were carried out, theoretical foundations of its performance are still not convincing enough, and the mechanisms for the dynamic processes and stability continue to not be fully understood. In order to develop a mechanistic understanding of foamy oil flow in a porous medium, laboratory experiments under two different well arrangement scenarios were considered, single-well and multi-well injection schemes, using methane and air as the injection gasses. Single-well CSI scheme injection experiments were performed in order to understand, in a more representative manner, the foamy oil generation by injecting gas externally to post-CHOPS reservoirs. The multi-well CSI scheme was considered to be applied in thin heavy oil reservoirs, and post-CHOPS reservoirs. For both arrangements, different injection strategies were performed, based on alternating gas injection and simultaneous gas injection. It was observed that on a single-well injection scheme, injecting a mixture of air and methane simultaneously can help to obtain larger recovery factors per cycle than when using methane alone. On a multi-well injection scheme, it has been observed that an alternating gas injection strategy has a better performance than the simultaneous injection. Using air has been observed to save methane usage up to 26% and 51% in single-well and multi-well injection schemes, respectively. Furthermore, in order to study the efficiency of using methane, air, and their mixture to generate stable foamy oils, observational experiments were performed by means of macroscopic (naked eye) and microscopic visualization which was interpreted through foamy oil stability parameters such as time of foamability and collapse, number of gas bubbles, gas bubbles distribution, and maximum bubble size. Using a mixture of air and methane has been observed not only to expand the volume of oil by 2.5 (volume expansion caused by methane has been found to be as high as 3.0) but also to delay the defoaming process.Canadá. University of Alberta : Thesis-Based Master's Recruitment ScholarshipTesi

Negligible Forchheimer effect for a maximum gas flow rate in a gas condensate reservoir

In this paper the optimal gas flow rate in a retrograde gas condensate reservoir has been calculated in order to minimize retrograde condensation, maximizing the slip velocity, due to the positive coupling effect; and minimizing the pressure drawdown, due to the Forchheimer effect (non-Darcy effect, inertial effect). Non-Darcy behavior has been thoroughly described because of its importance for describing additional pressure drawdown (more than expected by Darcy equation) in fluid flow in porous media, in situations where high velocity occurs. The coupling effect explains the increment of the gas-condensate relative permeability with increasing velocity and decreasing the interfacial tension. The Forchheimer equation has been used to calculate the bottom-hole flowing pressure for different gas flow rates. Because of the second term in the Forchheimer equation, which is function of the square of the superficial velocity of the fluid, this obtained value is less than the bottom-hole flowing pressure obtained from Darcy equation. This is important because a higher quantity of condensate liquids is obtained, which reduces the relative permeability, and as a result, the gas flow rate decreases due to this effect. For those different gas flow rates, the optimal gas flow rate, where the bottom-hole flowing pressure is acceptable, has been found. The novelty of the present work, is to present the optimal point where the gas flow rate is maximum, in which the non-Darcy effect is negligible.En el presente trabajo se calcula el caudal óptimo de gas de un yacimiento de gas condensado retrógrado, con el objetivo de reducir la condensacion retrógrada, maximizando la velocidad de arrastre debido al efecto coupling y minimizando la caída de presión debido al efecto Forchheimer (efecto no-Darcy, efecto inircial). El comportamiento inercial ha sido estudiado ampliamente debido a su importancia en describir la caida de presión adicional (más de la esperada de acuerdo a la ecuación de Darcy) en el flujo de fluidos en medios porosos, en situaciones de gran velocidad. El efecto de acoplamiento, explica el incremento de la permeabilidad relativa de gas condensado al incrementar la velocidad y disminuir la tensión interfacial. La ecuación de Forchheimer se utilizó para calcular la presión de fondo fluyente a diferentes caudales. Debido al segundo término en la ecuación de Forchheimer, la cual es función del cuadrado de la velocidad superficial del fluido, este valor obtenido resulta siendo menor a la presión de fondo fluyente obtenida mediante la ecuación de Darcy. Esto es importante pues se acumula una cantidad mayor de líquidos, lo cual reduce la permeabilidad relativa, y como consecuencia, el caudal de gas disminuye. Para los caudales de gas propuestos, se encuentra el caudal de gas óptimo, la cual es aquella donde la presión de fondo fluyente es aceptable. La novedad del presente trabajo, es la presentación de un punto óptimo, en el cual el caudal de gas es máximo, para el cual el efecto inercial es despreciable en comparación con el efecto coupling

Negligible Forchheimer effect for a maximum gas flow rate in a gas condensate reservoir

En el presente trabajo se calcula el caudal óptimo de gas de un yacimiento de gas condensado retrógrado, con el objetivo de reducir la condensacion retrógrada, maximizando la velocidad de arrastre debido al efecto coupling y minimizando la caída de presión debido al efecto Forchheimer (efecto no-Darcy, efecto inircial). El comportamiento inercial ha sido estudiado ampliamente debido a su importancia en describir la caida de presión adicional (más de la esperada de acuerdo a la ecuación de Darcy) en el flujo de fluidos en medios porosos, en situaciones de gran velocidad. El efecto de acoplamiento, explica el incremento de la permeabilidad relativa de gas condensado al incrementar la velocidad y disminuir la tensión interfacial. La ecuación de Forchheimer se utilizó para calcular la presión de fondo fluyente a diferentes caudales. Debido al segundo término en la ecuación de Forchheimer, la cual es función del cuadrado de la velocidad superficial del fluido, este valor obtenido resulta siendo menor a la presión de fondo fluyente obtenida mediante la ecuación de Darcy. Esto es importante pues se acumula una cantidad mayor de líquidos, lo cual reduce la permeabilidad relativa, y como consecuencia, el caudal de gas disminuye. Para los caudales de gas propuestos, se encuentra el caudal de gas óptimo, la cual es aquella donde la presión de fondo fluyente es aceptable. La novedad del presente trabajo, es la presentación de un punto óptimo, en el cual el caudal de gas es máximo, para el cual el efecto inercial es despreciable en comparación con el efecto coupling.In this paper the optimal gas flow rate in a retrograde gas condensate reservoir has been calculated in order to minimize retrograde condensation, maximizing the slip velocity, due to the positive coupling effect; and minimizing the pressure drawdown, due to the Forchheimer effect (non-Darcy effect, inertial effect). Non-Darcy behavior has been thoroughly described because of its importance for describing additional pressure drawdown (more than expected by Darcy equation) in fluid flow in porous media, in situations where high velocity occurs. The coupling effect explains the increment of the gas-condensate relative permeability with increasing velocity and decreasing the interfacial tension. The Forchheimer equation has been used to calculate the bottom-hole flowing pressure for different gas flow rates. Because of the second term in the Forchheimer equation, which is function of the square of the superficial velocity of the fluid, this obtained value is less than the bottom-hole flowing pressure obtained from Darcy equation. This is important because a higher quantity of condensate liquids is obtained, which reduces the relative permeability, and as a result, the gas flow rate decreases due to this effect. For those different gas flow rates, the optimal gas flow rate, where the bottom-hole flowing pressure is acceptable, has been found. The novelty of the present work, is to present the optimal point where the gas flow rate is maximum, in which the non-Darcy effect is negligible