Chemical Compositions And Viscosity-temperature Characteristics Of Produced Fluid From High Concentrated Polymer Flooding

With increasing the oil extraction,the oilfield production has developed the secondary and tertiary recovery.Especially,the development of polymer flooding is widely spreading due to application of tertiary oil recovery technique.Polymer flooding plays an important role among the enhanced oil recovery methods.High concentrated polymer is a method that can further enhance oil recovery after the flooding from the normal concentrated polymer.It can lead to a significantly higher oil recovery than the normal polymer,and the treatment of produced fluid is easy,besides,it is economical.Even with the high enhanced oil recovery,the technology has produced a large amount of produced water containing the inorganic ions,oil,high concentrated polymer and suspended solid.Therefore,it will change the conventional composition,viscosity and suspended solid of the produced fluid.The viscosity is increased,and emulsification becomes much serious.The demulsification is specially complicated.As a result,oil-water separation and wastewater treatment become more and more difficult.Compared with the normal concentrated polymer which has been widely studied,the major properties of high concentrated polymer may be significantly different and unclear.As a consequence,a study on some properties of high concentrated polymer flooding is required,specially on composition and viscosity-temperature properties.For optimizing the treatment of produced fluid,it is of practical significance to reduce the oilfield pollution.The new purpose and conception are exactly exhibited in the study.Taking a production zone of high concentrated polymer flooding in the proper oilfield as an example,this paper systematically analyzes the chemical compositions of produced liquids from the high concentrated polymer flooding by modern analytical methods.According to the zone characteristics and domain materials for the phase formation,the chemical compositions are precisely classified by aqueous phase,oil phase and solid phase.Adopting the method of experimental research,the viscosity-temperature curves for the produced liquid from high concentrated polymer flooding were measured and the properties were revealed.It will provide the practical data for optimizing the treatment of produced liquid from high concentrated polymer flooding.The results show that firstly,the produced liquid consists of aqueous phase,oil phase,solid phase with domain materials for the phase formation.The deposit(solid phase)in produced liquid mainly contains three parts: aqueous part containing soluble inorganic anion and cation,suspended solids and PAM;oil part containing float oil,organics and bacteria;solid part containing mechanical impurities,scale and corrosion products,secondly,because of the existence of high concentrated polymer,insoluble materials in the produced liquid are high and with complicated compositions including self-contained PAM,wax crystal,salinity and bacteria,finally,shown as the viscosity-temperature regularity and property,viscosity is inversely proportional to the temperature with greatly reducing viscosity by raising temperature.The mechanisms show that the increasing temperature can promote the degradation of the partially hydrolyzed PAM in produced liquid.Then,the molecular chains are broken from macromolecules to micromolecules,which reduces the viscosity and emulsification of produced liquid at the same time.