A Review on the Use of Chemicals as Steam Additives for Thermal Oil Recovery Applications

This study conducts a literature survey on the chemical steam additives tested in both lab and field settings from 1982 to present (2020). We summarize the major recovery mechanisms of both steam-based recovery process and steam-chemical-based recovery process. Next, we review the previous lab-scale/field-scale studies examining the applications of surfactants, alkali, and novel chemicals in the steam-based oil recovery process. Among the different surfactants studied, alpha-olefin sulfonate (AOS) and linear toluene sulfonate (LTS) are the recommended chemicals for their foam control/detergency effect. In particular, AOS was observed to perform especially well in residual oil saturation (ROS) reduction and sweep efficiency improvement when being co-injected with alkali. Application of organic alkali (alone or with a co-surfactant) has also drawn wide attention recently, but its efficacy in the field requires further investigation and the consumption of alkali by sands/clay is often an inevitable issue and, therefore, how to control the alkali loss requires further investigation. Novel chemical additives tested in the past five years include fatty acids (such as tail oil acid, TOA-Na+), Biodiesel (o/w emulsion), along with other types of chemical additives including switchable hydrophilicity tertiary amines (SHTA), chelating agents, Deep Eutectic Solvents (DES), graphite and SiO2 particles, ionic liquids and urea. High thermal stability of some of the novel chemicals and their potential in increasing displacement efficiency and ROS reduction efficiency in the lab studies require further investigation for their optimized application in the field settings to minimize the use of steam while improving the recovery effectively. This review reveals that when being properly applied, chemical additives can improve oil recovery via steam foam control, detergency effect (IFT reduction and wettability control), and viscosity reduction. In certain cases, microemulsion generation could be observed (o/w or w/o) with the addition of chemical additives at steam condition (which leads to recovery improvement), but the microemulsion effect on the conformance control (separate from the foamy effect), is lacking detailed investigation.

Алгоритмы моделирования формирования и обработки информации в рентгеновской томографии пеноматериалов

Algorithms for modeling the spatial structure of foam materials for the formation of projections in X-ray computed tomography and subsequent reconstruction of the internal structure of the samples are proposed. Algorithms are the basis of numerical models of the analyzed systems as applied to foam control. To demonstrate the capabilities of the developed algorithms, synograms and results of reconstruction of the internal structure of foam materials samples with variation of their parameters were obtained.

Enhanced rhamnolipids production using a novel bioreactor system based on integrated foam-control and repeated fed-batch fermentation strategy

Background Rhamnolipid is the best known microbial-derived biosurfactants, which has attracted great interest as potential ‘‘green” alternative for synthetic surfactants. However, rhamnolipid is the major contributor to severe foam problems, which greatly inhibits the economics of industrial-scale production. In this study, a novel foam-control system was established for ex situ dealing with the massive overflowing foam. Based on the designed facility, foam reduction efficiency, rhamnolipid production by batch and repeated fed-batch fermentation were comprehensively investigated. Results An ex situ foam-control system was developed to control the massive overflowing foam and improve rhamnolipid production. It was found that the size of individual bubble in the early stage was much larger than that of late fermentation stage. The foam liquefaction efficiency decreased from 54.37% at the beginning to only 9.23 % at the end of the fermentation. This difference of bubble stability directly resulted higher foam reduction efficiency of 67.46 % in the early stage, whereas the small uniform bubbles can only be reduced by 57.53 % at the later fermentation stage. Moreover, reduction of secondary foam is very important for foam controlling. Two improved design of the device in this study got about 20% improvement of foam reduction efficiency, respectively. The batch fermentation result showed that the average volume of the overflowing foam was reduced from 58~640 mL/min to 19~216 mL/min during fermentation process, presenting a notable reduction efficiency ranging from 51.92% to 73.47%. Meanwhile, rhamnolipid production of batch fermentation reached to 45.63g/L, and the yield 0.76g/g was significantly better than ever reported. Further, a repeated fed-batch fermentation based on the overall optimization was carried out. Total rhamnolipids concentration reached 48.67 g/L with the yield around of 0.67-0.83 g/g, which presented an improvement of 62% and 49% compared with conventional batch fermentation by using various kinds of defoamer, respectively. Conclusions The ex situ foam-control system presented a notable reduction efficiency, which helped a lot to easily solve the severe foaming problem without any defoamer addition. Moreover, rhamnolipid production and yield by repeated fed-batch fermentation got prominent improvement compared to conventional batch cultivation, which can further facilitate economical rhamnolipids production at large scales.

Enhanced rhamnolipids production using a novel bioreactor system based on integrated foam-control and repeated fed-batch fermentation strategy

Background Rhamnolipid is the best known microbial-derived biosurfactants, which has attracted great interest as potential ‘‘green” alternative for synthetic surfactants. However, rhamnolipid is major contributor to severe foam problems, which greatly inhibits the economics of industrial-scale production. In this study, a novel foam-control system was established for ex situ dealing with the massive overflowing foam. Based on the designed facility, foam reduction efficiency, rhamnolipid production by batch and repeated fed-batch fermentation were comprehensively investigated. Results An ex situ foam-control system was developed to control the massive overflowing foam and improve rhamnolipid production. It was found that the size of individual bubble in the early stage was much larger than that of late fermentation stage and the foam liquefaction efficiency decreased from 54.37% at the beginning to only 9.23 % at the end of the fermentation. This difference of bubble stability directly resulted higher foam reduction efficiency of 67.46 % in the early stage, whereas the small uniform bubbles can only be reduced by 57.53 % at the later fermentation stage. Moreover, reduction of secondary foam is very important for foam controlling. Two improved design of the device in this study got about 20% improvement of foam reduction efficiency, respectively. The batch fermentation result showed that the average volume of the overflowing foam was reduced from 58~640 mL/min to 19~216 mL/min during fermentation process, presenting presented a notable reduction efficiency ranging from 51.92% to 73.47%. Meanwhile, rhamnolipid production of batch fermentation reached to 45.63g/L, and the yield 0.76g/g was significantly better than ever reported. Further, Moreover, a repeated fed-batch fermentation based on the overall optimization was carried out, total rhamnolipids concentration of 48.67 g/L was reached with yield around of 0.67-0.83 g/g, which presented an improvement of 62% and 49% compared with conventional batch fermentation by using various kinds of defoam, respectively. Conclusions The ex situ foam-control system presented a notable reduction efficiency, which helped a lot to easily solve the severe foaming problem without any defoamer addition. Moreover, rhamnolipid production and yield by repeated fed-batch fermentation got prominent improvement compared to conventional batch cultivation, which can further facilitate economical production of rhamnolipids at large scales.