Jennys Lourdes Meneses Barillas

Analysis of oil production by applying in situ combustion

ABSTRACT The THAI (toe-to-heel air injection) process is a process of enhanced oil recovery, which consists of integrating the in situ combustion process with technological advances of horizontal wells drilling, and has not yet been applied in Brazil. Motivated by this context, the authors aimed to studying the application of the THAI process in a semisynthetic reservoir, with characteristics similar to those ones found in the Brazilian Northeast. It was analyzed the air injection rate, indicating that there is a limit to reach a good efficiency.

Analysis of oxygen production by applying in situ combustion

ABSTRACT THAI (toe-to-heel air injection) is a process of enhanced oil recovery that consists of integrating the in situ combustion process with technological advances of horizontal wells drilling, and has not yet been applied in Brazil. Motivated by this context, this research aimed at studying the application of the THAI process in a semisynthetic reservoir, with characteristics similar to those found in the Brazilian Northeast. It was analyzed the air injection rate and produced oxygen, indicating that there is a limit to reach a good efficiency and minimized risk explosion.

Operational Conditions in Oil Recovery with Blanket Heating in Shallow Reservoirs

Abstract The most innovative proposals in the field of petroleum research refer to the oil recovery previously considered economically unviable in the market. Included in this premise is low °API oil, also known as heavy oil. Statistics show that, currently, the world reserves could be greatly improved by heavy oils contained in formations with depths between 50 m and 300 m, which are classified as shallow or ultra-shallow reservoirs. Thermal methods have been the most effective alternative for heavy oil recovery, and among them, there is the steam flood, the technique most often applied to reduce oil viscosity. A recently developed method, called Blanket Heating, combines some of the fundamental characteristics of thermal methods, adapting them to the particularities of the shallow reservoirs. This process works introducing steam in horizontal metal conduits, meaning that the heated fluid does not come into direct contact with the formation, working as a classical heat exchanger. The heating occurs indirectly, avoiding problems such as the recovery of large amounts of water and the insertion of excessive volume of steam, especially in cases where the depth is minimal and the overlying pressure is insufficient to contain the fluid. The primary focus of the article is to examine the influence of parameters involved in the operation of blanket heating, in order to find an optimal operational configuration. The choice of the horizontal direction for conduits reflects the need to maintain the greatest possible contact area between conduits and oil reserves. The results show that the blanket heating may be a viable process for heavy oil recovery in extremely shallow formations. They also show that oil recovery can be maximized in proportion to the increase of temperature in the conduits and the number of conduits. The cumulative oil production is reduced when the distance between the conduits and producer wells or between the own conduits is greater. In addition, the results were better when the completion interval of producer wells and the position of the conduits in relation to the vertical are arranged between the center and base of the reservoir. The inner diameter of the conduits was the only parameter that had minimal influence, showing no significant alterations in the production of oil. The study also showed that the blanket heating does not produce significant emissions of steam to the surface, confirming the reduction in the amount of water produced. In the face of the growing importance of heavy oil on the world market, together with the successful exploration of this resource, and knowing the current applicability of the steam flood as the main alternative to the economic recovery of this type of oil, justify the need to a study that will expand the options to use this method in reservoirs that retain great amount of viscous oil at lower depths.

Optimization of Steam and Solvent Injection as an Improved Oil Recovery Method for Heavy Oil Reservoirs

Abstract Currently a resource more and more used by the petroleum industry to increase the efficiency of steam flood mechanism is the addition of solvents. The process can be understood as a combination of a thermal method (steam injection) with a miscible method (solvent injection), promoting, thus, reduction of oil viscosity and interfacial tensions between injected fluid and oil. Solvents are hydrocarbons well known for reducing these tensions and facilitating the production of heavy oil. The use of solvent alone tends to be limited because of its high cost. When co-injected with steam, the vaporized solvent condenses in the cooler regions of the reservoir and mixes with the oil, creating a zone of low viscosity between steam and heavy oil. Mobility of the displaced fluid is then improved, resulting in an increase of oil recovery. To better understand this improved oil recovery method, a numerical study of the process was done contemplating the effects of some operational parameters (distance between wells, steam injection rate, solvent type and injected solvent volume) on cumulative oil production and oil rates. A semi synthetic model was used. Some reservoir data were obtained similar to those found in Brazilian Potiguar Basin and others ones were obtained from literature. Simulations were performed in STARS (CMG, 2007.11). It was found that injected solvent volumes increased oil recovery and oil rates. Further, the majority of the injected solvent was produced and can be recycled. High initial productions achieved by models that use solvent have normally a significant impact on the operation economics, because earlier productions suggest that fluids injection (steam and solvent) can be interrupted earlier. On environmental point of view, it would have a reduction of energy and water consumptions for steam generation, having diminished Green House Gases (GHG) emissions. Also it is important to emphasize that the high oil rates presented by these models can generate an earlier financial return, and this would be decisive for the economic viability of the project.