With the passage of time, it is becoming extremely difficult to discover new oil fields. Most of the sedimentary basins that might contain oil have already been explored and new discoveries tend to be small. Moreover, the unexplored basins happen to be in remote and ecologically sensitive areas around the world. Despite the existence of huge volumes of unconventional energy sources, the technologies to exploit them are surrounded by controversies and remain politically or environmentally sensitive. At the moment, they cannot be applied at scale. Against this backdrop, enhanced oil recovery is helping firms expand their base business.
Considering the gigantic scale on which the industrial landscape of energy operates, the challenges are numerous. In the here and now, fulfilling the global energy demand is the most formidable concern. In order to meet the ever-expanding energy demand all across the globe, technology has to step ahead every moment, redefining the available sources of energy.
Enhanced Oil Recovery is one method that allows oil producers to extend the life of mature fields and get more production from existing assets.
Let’s learn about the new EOR technologies
- SAGD – Steam Assisted Gravity Drainage This method is employed for improving the recovery of heavy crude or bitumen. In sync with the other conventional methods, it effectively brings down the viscosity of oil through a rise in temperature. In this method, two parallel horizontal wells are used, 500m and 1000m in length respectively. Generally, they are drilled one over the other, 5 to 10 m apart. The lower well finds its place close to the bottom of the deposit. A ‘steam room’ is created as the steam is injected into the upper well, from where it permeates through the space beneath, providing heat to the reservoir. Owing to the forces of gravitation, the heated up oil and condensed team reach the lower production well, where the fluid recovery occurs. During the process, the ‘steam room expands in all possible directions. In order to optimize the SAGD process, it is important that the lower part of the room is located immediately over the production wells. Moreover, the steam produced from this part of the room should be minimal. Expected oil recovery through the employment of this method is 50-75% of resources.
- Vapex (Vapor extraction) Aimed at considerably reducing the viscosity of crude and bitumen, Vapex makes use of gaseous hydrocarbon solvent injection. The application of Vapex in the oil industry is quite frequent. Positive results through this method have been observed in thin beds or highly water-saturated beds, in unfavorable and unprofitable thermal methods. Two horizontal wells are drilled with the injection well above the production well. The oil that has been diluted is sufficiently mobile to enable a flow of gravity towards the production well near the bottom of the reservoir, and from where it is pumped out to the surface. A ‘steam room’ is formed as the pore spaces surrounding the injection well are filled up with a gaseous solvent. The room begins to expand as the flow and solving processes continue. As it reaches the reservoir top, it expands sideways. following which, the oil-gas contact declines and the production of oil decreases. This process will continue to find application as it is still profitable. In order to bring about economic efficiency, carbon dioxide is being proposed as the main solvent instead of propane or butane. Moreover, carbon dioxide is eco-friendly!
- LTO – Low-Temperature Oxidation This light oil enhancement recovery technique employs the oxidation processes occurring in low-temperature conditions between the injected air and oil. During these reactions, all oxygen injected with the air is absorbed, consequently protecting against its penetration to the production well. This further safeguards the process itself. In the course of LTO process, the reaction takes place spontaneously and independently of the oxygen pressure giving rise to the production of combustion gases which cause the oil movement in the reservoir. Hence, the main goal of this process is to generate nitrogen and carbon dioxide, which provide immense energy for the production. During the drilling operations, a system of two vertical wells- injection and production is made at a distance of a few hundred meters from each other. In the zone of oxidation, the oxygen is entirely absorbed from the injected air. Depending on the reactivity of oil, it may oxide slowly or quickly, but always at a comparatively low temperature of 100–250 °C. During the reaction with oxygen, only a small part of the oil is absorbed. The remaining oil moves under the influence of the produced gases.
- Multilateral Wells The early 1990s witnessed an increased interest in complex geometry wells or multilateral wells. The application of multilateral systems has opened up huge possibilities of economic and technological optimization, contrary to the conventional systems. The potential profits from the use of multilateral wells frequently can be divided into two categories. The first category gives a possibility to increase reserves and/or accelerate the production from specific wells. The other one creates possibilities of bringing down the costs of the exploitation project realization. However, there are risks involved in multilateral well construction and efforts are being made to minimize these risks.
- Green Flooding A major breakthrough in EOR is the use of green surfactant which has shown an oil recovery of 96.5% at reservoir temperature Presently, most of the available surfactants used in oil recovery operations are either ineffective in high salinity or high hardness waters. At times, they are also incapable to stand the higher temperatures encountered in many formations. This powerful natural product enhances recovery from oil reservoirs through the decline of interfacial tension and increases the volumetric sweep efficiency of fractured or heterogeneous oil reservoirs. This novel green surfactant for EOR is extracted from two plants available in the United Arab Emirates (Product A and Product B). This natural agent proves to be very effective in formations containing water whose salinity is from 70,000 to 180,000 parts per million total dissolved solids and also having temperatures as high as 100 °C. The agent is mixed with the formation water and is stable over a wide range of formation temperatures and water salinity. The possibilities of ‘green flooding’ are under consideration as it is an environmental friendly product. This product has
The way forward
Against the background of geopolitical conflicts, fluctuating oil prices, and environmental concerns, new technologies need to be supported for enhanced oil recovery. With the wide application of EOR, oil production will scale up leading to a harmony between demand and supply.