Application Study On Technological Policy Of Viscosity-reducing Cold Heavy Oil Production In Heavy Oil Reservoir

With the increase of conventional crude oil extraction,the exploitation of oil fields is progressing in depth,and heavy oil will become one of the important energy sources in the future.Heavy oil reserves in Xinjiang oilfields are abundant,but many heavy oil reservoirs cannot be exploited by conventional thermal recovery because of the decentralized blocks,small oil-bearing areas,thin oil reservoirs,remote locations,exploration wells,test production wells,and test wells in the early stages of development.This paper uses the emulsification and viscosity reduction method to improve the development of heavy oil extraction in Chepaizi and Hongshanzui Blocks of Xinjiang Oilfield.According to the geological characteristics of Chepaizi and Hongshanzui blocks,we research the technology definition method,which is suitable for the cold production and viscosity reduction process.First,the viscosity,density,and acid value of the heavy oil in the target block were measured,as well as the relationship between the viscosity and the temperature and the rheology;the formulation and the property evaluation of the emulsified viscosity reducing agent were determined.The technical definition method for on-site application of the cold tapping process was established by combining the radial flow formula of the plane and the empirical calculation formula of the starting pressure gradient;the effect of the single construction parameter(viscosity reducing agent,viscosity injection rate,viscosity injection temperature,and well-removal time)on the viscosity-reducing effect of thick oil emulsified formations was studied first through the indoor physical simulation experiment.Then the effects of multiple construction parameters on the viscosity-reducing effect of thick oil emulsified formations were investigated by combining orthogonal tests,and the process parameters for emulsifying and viscous reduction of heavy oil are determined;finally,the necessity of the viscous oil viscous emulsification and viscosity reduction in the well area is determined by the technical definition method of the cold production and viscosity reduction process on site.If necessary,the viscous oil emulsification and viscosity reduction field test is performed,and verify according to the construction effect.The results of the study indicate that the heavy oil emulsification viscosity reduction system for well h0617 in Hongshanzui block is:HD-3(0.5%)+ AP-P4(500mg/L),the emulsification and viscosity reduction system in well DC332 well of Chepaizi block is:HD(0.5%)+ NaOH(0.2%)+ AP-P4(600mg/L).The viscosity reduction rate is above 90%,and the stabilization time is all over 24h.Combined with the radial flow formula and the empirical calculation formula of the starting pressure gradient(Syrian O oilfield startup pressure gradient fitting formula),the technical demarcation method was established for field application of cold tapping and viscosity reduction technology.It is found through one-dimensional sand filling tube model heavy oil emulsification viscosity reduction laboratory experiments that the suitable injection amount of the adhesive is 0.45PV,and the suitable injection speed is 0.2mL/min,and the suitable emulsification time is 24h,and the suitable injection temperature is 25?50?.Based on the two-dimensional plate model emulsification viscosity reduction chamber physical simulation orthogonal tests,the impact of various parameters on the recovery ratio from the largest to the smallest in order are:injection of viscosity reducer,injection rate of viscosity reducer,injection temperature of viscosity reducer,and well-decrease time.Using the technical definition method of on-site application of cold-tightening and viscosity-reducing technology,it was determined that both h0617 well and DC332 well need to be emulsified and viscous-reduced heavy oil construction,and the construction effect of the mine site is well.