The High-temperature-enduring Viscosity Reduction Agent Preparation And The Working Scheme Design For Super Heavy Oil Of Du-84 Block In Liaohe Oil Field

The main components of high-temperature-enduring viscosity reduction agent were prepared in laboratory according to the basic property of Du-84 in Liaohe oil field. A complex viscosity reduction agent was made by mixing them up,which is suitable for both the well-bore viscosity reduction production and the cyclic steam stimulation production of the super heavy oil in Liaohe oil field. In order to practice the regular production of the super heavy oil in Liaohe oil field,the super heavy oil (acid value: 5.89mgKOH/g;viscosity:5464mPa?s at 80℃;H2O:9.0wt%)　was turn into O/W type emulsion,in which the volume ratio between oil and water is 70:30,by anion surfactant an,nonionic surfactant and other additives. the working scheme in situ was designed for Du-84 block based on the results of the experiments in laboratory. The way of injection and the operation in situ were discussed in this paper. The optimized formula is following: surfactant:0.2%wt; alkali: 0.1%wt;additive:0.2%wt. The experiment results show that the viscosity of the emulsion is 109.3mPa?s　at　80℃　and the viscosity reduction rate is 98.0%. The properties of the viscosity reduction agent prepared under the high temperature condition and the effect of the salinity in formation water on viscosity reduction rate were investigated to meet the need of the viscosity reduction at high temperature.The results show that the viscosity reduction agent behave well under 280℃,16000mg/L salinity and the viscosity reduction rate ,95.60%,can meet the need of the regular transportation in the late period of the thermal recovery under the condition of the amount of the viscosity reduction agent and the volume ratio between oil and water changing in a wide range,the results were optimized as following: the optimized amount of emulsifier in water: 0.5%wt; the optimized ratio between oil and water: 80:20~70:30,the viscosity of the O/W type emulsion: 109.3~386.2mPa?s at 80℃;dehydration rate after demulsification: >93.0%.The viscosity reduction property of the viscosity reduction agent and the stability of the emulsion can meet the need of the heavy oil production. The phase-turning of the heavy oil which contains water,and the effect of water content,temperature and shear rate on the rheological property of the heavy oil which contains water were aLso discussed,based on the results of the experiment on the heavy oil of the block in laboratory. The result showed the phase-turning point of the heavy oil in Du-84 block is 19%. In the study of viscosity reduction mechanism,it was found that the mixture of surfactants has the effect of synergistic enhancement,which improves the surface activity on the whole. The alkali and additives in the viscosity reduction agent have enhancement effect on the viscosity reduction according to the analysis of the effect of the components in the heavy oil on the viscosity. On the IR spectrum,the absorb peaks of the asphaltene and the rein were changed in some degree after viscosity reduction. It shows that the viscosity reduction agent molecules lay between the aslphsltene layer and the rein layer by the means of hydrogen bond formation,osmosis and dispersion,which destroy the overlapping planar assemble of the asphaltene and rein,and make it loose. The main viscosity mechanism of heavy oil is the ordered state of the assemble is destroyed.