Heavy Oil Emulsification Mechanism And Control Technology Research For Shang12-41Block

Steam stimulation is the main form of exploitation of heavy oil, however, injectionpressure is always high due to various factors in the steam stimulation process.There aremany factors that could cause the high injection pressure: the condensate water in displacingfront during steam stimulation is not compatible with the reservoir, which may cause theformation clay swell; formation damage by formation pollution; the oil may emulsify with thecondensate water to W/O emulsion with high viscosity, and so on. This paper studies thisissue from emulsion aspect. Physical simulation proves that injecting condensate water withhigh pH would cause high injection pressure, which is highly effected by formationpermeability. When permeability is higher than2000mD, the injection pressure is low; whenthe permeability is under2000mD, the injection pressure would rise rapidly. Microscopicvisualization proves that when condensate with high pH encounters oil, it would seep into oiland emulsify with oil to W/O emulsion with high viscosity. Emulsion experiment showed thatthe highest moisture content is70%and viscosity is20times that of the oil. We couldconcluded that the cause of the high pressure is the oil emulsify with the condensate water toW/O emulsion with high viscosity. On this basis, this paper studied two kinds of methods thatcould reduce injection pressure. One method is reverse phase technology, mechanism ofwhich is that oil and condensate water could emulsify to O/W emulsion, viscosity of which issmall. This paper determined the1%DSB-13to be reverse phase agent throughemulsification rate, emulsion stability, interfacial tension and thermal stability evaluation.Physical experiment showed that1%DSB-13could effectively reduce the injection pressure.The other is non-emulsion technology, mechanism of which is to prevent oil and wateremulsify by controlling pH of condensate water. This paper determines the BA to be thenon-emulsion agent and N, N-dimethyl formamide to be the carrying agent through solubility, acidity, and corrosive. Physical experiment shows that the non-emulsion system couldeffectively reduce the injection pressure, and the field application also shows the same effect.