Study On The Performance And Application Of Foam Flooding Systems With Ultralow Interfacial Tension Based On Alkyl Glycoside

Efficiently exploitation and utilization of the crude oil is an important strategydealing with the global energy shortage,especially taking into consideration of the further exploitation of the exhausted old oil fields.Therefore,effective novel techniques are still needed to enhance oil recovery(EOR).Foam flooding is regarded as one of the promising techniques in EOR,which not only has the characteristic of selective blocking,but also has a certain ability of washing oil.Foam flooding system with Low tension,which has a good plugging performance and washing oil capacity,can greatly improve the tertiary fuel efficiency one time.Stabilizing the foam and reducing the oil-water interfacial tension are related to the performance of the surfactant at the interfaces of gas-liquid and the oil-water,respectively.It is difficult to both achieve the optimization of these two aspects at the same time.Therefore,todesign a well foam flooding system is critical but difficult.In this paper,a green surfactant alkyl glycoside(APG)was chosen as the main agent,the interfacial properties of APG and the interactions of APG with other surfactants were studied.An environment-friendly and low-tension foam flooding system was designed based on the APG.The foam properties and interfacial activity of the system were investigated systematically.The foam activity,interfacial activity,sealing capacity,oil resistance,adsorption loss,and enhanced oil recovery were investigated.The results indicate that the designed system has excellent performance.This work examined the performance and the application of the novel efficient environmental-friendly oil displacement system,which might have a positive effect on the application of tertiary oil recovery technology.The paper is divided into five chapters.The first chapter summarizes the current development of tertiary oil recovery technology,giving out the important prospect of foam flooding,accompanied by the significance of this thesis.The second chapter introduces the research methods adopted in this paper.The research content is divided into three parts:In the first part(Chapter 3),the foaming properties and the interfacial activity of the green surfactant alkyl glucoside(APG)were studied.The effects of environmental conditions,such as concentration and inorganic salt ions,were investigated..The effects of nano-microcrystaffine ceiiutose ana other surractants on the properties or APG were investigated.The experimental results show that APG has good foaming property,but which was weaken with the inorganic salt concentration increasing.The static stability of APG foam is better comparing with the dynamic stability,and the foam activity was significantly enhanced after mixing with nano-microcrystalline cellulose.After the APG were mixed with other surfactants such as alkanolamides.the interfacial tension of the system was significantly decreased,and the interfacial activity was further improved by increasing the concentration of inorganic salts.In the second part(Chapter 4),the foam properties and the interfacial activity of APG and dodecyltrimethylammonium bromide(DTAB)and sodium dodecyl sulfate(SDS)were studied.The effects of the mixed ratio,concentration and inorganic salt ion on the foam stability and oil-water interfacial activity were investigated.The results show that the foaming and foam stability of the APG/DTAB/SDS complex system are better than those of single surfactant system.The foam stability and interfacial activity are increasing with the increasing of inorganic salt ion concentration.The system has excellent foam properties over a wide range of concentrations and comparisons,which can reduce the oil-water interfacial tension to a low level.The system can maintain a good performance at a total salinity of 32,000 ppm,which demonstrate that the system has a good prospect in high salt reservoir.In the third part(Chapter 5),the blocking ability,oil resistance and solid-liquid interface adsorption loss of APG-based multi-component foam system were investigated.The one-dimensional model indoor model flooding test was used to evaluate the oil recovery effect.The results show that the system can play a good plugging profile both in higher and lower perrmeability cores,which indicates that the system can be applied to conventional reservoirs and high salt reservoirs with low permeability.The multi-complex system has poor oil resistance at low concentration,but the oil resistance is improved by the concentration increasing.The addition of polymer can improve the oil resistance of the system.The results of oil displacement show that the total recovery of foam flooding after water flooding increased by 25%-32%OOIP.The system not only has high performance,but also has environment friendliness,which will has very good potential application in EOR.