Investigating The Stabilization Mechanism Of The Crude Oil Emulsion In Oil Field And Designing The Demulsifier

As the commonly used technology of the tertiary oil recovery phase, Binaryflooding can increase the oil content of the produced fluid in the oil field, but itmakes the components and the stabilization mechanism of the produced fluid morecomplicated at the same time, which will bring more difficulties for the demulsification of the produced fluid. Therefore, exploring the impact of surfactant,polyacrylamide, inorganic salts and pH on the stability of the oil-water interfacialfilm of the produced fluid, which can provide theoretical guidance for the designand synthesis of the new and efficient demulsifier, is of significant importance inapplication. There are many reports about the influence of these factors on theoil-water interfacial film, and the methods and means reported are usuallyqualitative and indirect, but the Langmuir technique can be used to study thestability of oil-water interfacial film quantificationally in the molecular level.Firstly, the oil and water components of the produced fluid are analyzed usingelectrospray ionization mass spectrometry, thermal analysis, nuclear magneticresonance analysis and gas chromatography-mass spectrometry methods; Theinfluence of natural surfactant, petroleum sulfonate, polyacrylamide, inorganicsalts and pH on the stability of the oil-water interfacial film are investigated in theLangmuir interface with Langmuir-Blodgett technology, and the influence ofdemulsifiers with different monomer ratios and structure on the stability of theoil-water interfacial film are also investigated in the Langmuir interface. Concretecontent is as follows:1. The water components of the produced fluid are analyzed using electrosprayionization mass spectrometry, the oil components of the produced fluid are analyzedusing thermal analysis and nuclear magnetic resonance analysis, and thecomponents of the produced fluid are analyzed using gas chroma-tography-massspectrometry methods. The results show there was a certain amount ofpolyacrylamide and a small amount of water dispersible asphaltene and resin in thewater phase of the produced fluid, which could enhance the stability of theproduced fluid; The content of the alkanes and the aromatics with low molecularweight in the oil phase of the produced fluid was about91%, the content of asphaltene, resin and wax with great molecular weight was about9%, which werethe main factors for the stability of the produced fluid. In addition, there was a smallamount of non-aromatic hydrocarbons surfactants exiting in the oil phase; Therewere17kinds of surfactants in the produced fluid and their content were higherthan0.05%, and the content of the surfactant with formula C11H19NO4was up to11.337%, which was one of the main surfactants in the produced fluid as awater-soluble surfactant.2. Spreading the crude oil-toluene solution in the Langmuir interface, and theeffects of natural surfactant, petroleum sulfonate, CaCl2, NaCl, partially hydrolyzedpolyacrylamide and pH on the stability of the interfacial film are investigated in theLangmuir interface. The results show that with the increasing of the volume of thecrude oil-toluene solution, the asphaltene content in the Langmuir interfaceincerased and the stability of the interfacial film was enhanced; Increasing thepetroleum sulfonate concentration, the stability of the interfacial film was alsoenhanced; Partially hydrolyzed polyacrylamide could increase the stability of theinterfacial film at a relatively high concentration; The stability of the interfacial filmwas improved when the CaCl2concentration increased; When NaCl concentrationincreased, the stability of the interfacial film was also enhanced first and thenlowered; A high or low pH could enhance the stability of the interfacial film.3. Spreading the crude oil-toluene solution in the Langmuir interface, and theeffects of demulsifiers with different monomer ratios and structure on the stabilityof the interfacial film are investigated in the Langmuir interface. The results showthat when the mass ratio of the aryl group contained in the demulsifiers with B-typestructure was85.38%, the stability of the interfacial film had a largest decline,indicating the demulsification of this demulsifier was best. Within a certain range ofconcentration, with the increasing of this demulsifier concentration, the stability ofthe interfacial film was lowered, when the concentration of this demulsifier arrivedat120ppm, on the contrary, the increasing of the concentration could enhance thestability of the interfacial film.