In view of the fact that a large amount of crude oil has not been produced in some old blocks of Liaohe Oilfield after water flooding, polymer flooding with surfactant can reduce the interfacial tension between oil and water, increase the swept volume and improve the oil washing efficiency. Using binary compound flooding technology, the old block after water flooding can achieve good dehydration and oil increase effect.
Keywords: binary compound flooding; Polymer; Surfactant; Viscosity shear
At present, every one percentage point increase in oil recovery of old oilfields in China can increase recoverable reserves by more than 654.38 billion tons. Since 1996, the tertiary oil recovery output of China Petroleum has gradually increased. 1996 is 3.59 million tons, and it broke through100000 tons for the first time in 2000, reaching100000 tons. Since then, the output has remained above100000 tons for six consecutive years. In 2005, it reached13.23 million tons, accounting for 12.5% of China's annual oil production. This makes the tertiary oil recovery technology, which can greatly improve the oil recovery, attract much attention.
Tertiary oil recovery is a leap in oilfield development technology. Compared with primary oil recovery and secondary oil recovery, it relies on the dual effects of physics and chemistry to improve oil recovery efficiency. After more than ten years of continuous research and practice, three different tertiary oil recovery technologies have been developed in domestic oil exploitation industry: polymer flooding technology, binary compound flooding technology and ternary compound flooding technology.
1 and binary compound flooding technology and mechanism
1. 1 binary compound flooding technology
Binary compound flooding technology is the combination of polymer and surfactant, mainly surfactant, to reduce the interfacial tension between oil and water in the system. By adding polymer, the viscosity of the system is increased, and the sweep volume of water flooding is enlarged, so as to better improve the oil displacement effect of the composite system. It is an effective technology to improve oil recovery at present.
According to the reservoir properties of different oilfields in China, after adjusting the molecular weight and concentration of polymers and screening the properties of surfactants, binary compound flooding technology will be widely used.
1.2 oil displacement mechanism of binary compound flooding
Mechanism of polymer flooding: Adding water-soluble polymer into injected water can increase the viscosity of injected water, improve the viscoelasticity of oil displacement system, and reduce the mobility ratio of injected liquid to crude oil, thus starting the remaining oil. Mechanism of surfactant flooding: by adding surfactant, the interfacial tension between oil and water is reduced, so that the cohesion of remaining oil is reduced, thus improving oil displacement efficiency. The oil displacement mechanism of binary compound flooding is to organically combine polymer flooding and surfactant flooding. Surfactants reduce the interfacial tension between oil and water, resulting in "emulsified oil droplets" and "oil filaments" in the residual crude oil in the formation. The added polymer makes the injection fluid have a large shear viscosity, which leads to the "oil filaments" being pulled off by the shear of the injection fluid, and the formed oil droplets are driven to the vicinity of the oil production port and recovered.
1.3 binary compound flooding process flow
1.3. 1 injection process of binary compound flooding (see figure)
2. Application status of binary compound flooding technology in China.
Daqing Oilfield, Shengli Oilfield and Liaohe Oilfield have successively carried out theoretical research and practical popularization of binary compound flooding technology. In September, 2003, Shengli Oilfield took the lead in carrying out the industrial test of binary compound flooding in Ng54-6 1 layer in the southwest of Zone 7 of Gudong Oilfield, which marked that Shengli Oilfield became the first oilfield in China to apply and popularize binary compound flooding technology industrially. By the end of 2008, the oil production in the center well area of fast in the southwest experimental area of Area 7 of Gudong Oilfield has increased by 65,438+10,000 tons, and the oil recovery has increased by 654.38+04.7%. The total oil production in the whole experimental area increased by 20 1 1,000 tons, and the oil recovery increased by 7.25%.
1In March, 1993, Liaohe Oilfield conducted a surface technology test of polymer flooding in the east area of Jin 16 block. Due to the large viscosity shear range of injected polymer solution, the actual and dynamic response effects are poor. In view of these problems, we have carried out analysis and research, found out the reasons and taken targeted measures, and the test effect has been continuously improved.
65438-0996 carried out the pilot test of "polymer-alkali" binary compound flooding in Xing 28 block of Liaohe Oilfield, and achieved good results. Among them, the comprehensive water cut of Xing 1 well decreased from 98.4% to 85.6%, and the oil production increased from 0.9t/d to14.5 t/d. The peripheral observation wells also achieved good results. The comprehensive water cut of Xing 19 1 well decreased from 98.2% to 74.9%, and the oil production increased from 2.2t/d to14.2t/d. In 2000, the industrial ground test of "polymer+alkali" binary composite flooding was carried out in Shu 22 polymer injection station, which was the first time for binary composite flooding technology in Liaohe.
During the period of 1997, the scientific research department of Liaohe Oilfield organized a systematic study on ASP flooding technology, and conducted theoretical demonstration and laboratory tests on related technologies, which provided theoretical and experimental data support for the later ground test of ASP flooding technology in Liaohe Oilfield.
In 2007, in view of the fact that the Jin 16 block in Liaohe Oilfield entered the stage of double high oil recovery after water flooding, the existing technology could not improve the oil recovery. A large-scale theoretical test and research on binary compound oil displacement technology are carried out. Based on the analysis and data simulation of formation reservoir, the tertiary oil recovery development scheme of this block is determined by using the binary compound flooding technology of "polymer-surfactant". In 20 10, the industrial test of binary compound flooding will be carried out in Jin 16 block, which will lay the foundation for the popularization and application of this technology in various blocks of Liaohe Oilfield.
3. The development prospect of binary compound flooding technology in Liaohe Oilfield.
Through the demonstration and test of tertiary oil recovery technology in recent 20 years, combined with the actual situation of Liaohe Oilfield, two main tertiary oil recovery technologies, polymer flooding and "polymer-surfactant binary compound flooding", have been formed. As a mature tertiary oil recovery technology, polymer flooding has been widely used in various blocks of Liaohe Oilfield. However, due to the limitation of the technology itself, the oil recovery can only be increased by 7% ~ 10%, and more than 50% of the crude oil in the reservoir has not been produced after polymer flooding. In order to improve oil recovery, two technologies, binary compound flooding and ternary compound flooding, have been developed on the basis of polymer flooding. However, the main component "alkali" in ASP flooding is easy to scale and block pipeline equipment under the water quality conditions in Liaohe Oilfield, so the development of this technology in Liaohe Oilfield is seriously restricted by the water quality. Combining the advantages of polymer flooding and ASP flooding, surfactant is added on the basis of polymer flooding, and alkali is removed on the basis of ASP flooding, forming a "polymer-surfactant" ASP flooding technology suitable for the actual situation in Liaohe Oilfield.
The industrial test of "polymer-surfactant" binary compound flooding is of great significance in Liaohe Oilfield. The successful application of this technology will make an important contribution to increasing production, revitalizing old blocks and increasing recoverable reserves in Liaohe Oilfield.
refer to
1. Wang Lifang. Exploration on development of Ng54-6 1 binary compound flooding. Inner Mongolia Petrochemical Company, 2009.
2. Looking for the Long March. Study on scaling mechanism and control of binary compound flooding in Gudong Oilfield. Shandong Chemical Industry, 2008.
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