Research On The Laboratory Test Of Viscosity Reduction For Heavy Oil Of Daqing Peripheral A Block

Daqing peripheral A block was located on 2-noselike structure of southwest area of Taikang up-lift in west slope block of Songliao basin,which was divided into Quantou group,Qingshankou group,Yaojia group,Nenjiang group,Sifangtai group,Mingshui group,tertiary and quaternary strata from bottom to top.This is whole layered structure reservoir,which is on the effects of physical properties of rock,however there are differences between layers.In order to improve production of heavy oil in this block,lots of oil driving experiments were conduct focus on relative processes about cold recovery and viscosity reduction of heavy oil,to obtain optimal recovery process,which provides guidance for recovery of heavy oil,ensuring effective recovery.Various driving experiments,including thermal recovery,chemical driving,foam driving,flue gases driving,were conduct,focus on behaviors of heavy oil in A block,and for each driving process,changes of recovery were observed by changing one factor,combined with various devices and methods,and the optimal one was selected.Results indicate that viscosity changes quickly with increase of temperature,when exceeds to 80?,slope of viscosity reduction tend to gentle,so ultimate recovery of heavy can be largely improved when temperature beyond 80?.The recovery factor below 60? was 27.9%,and beyond150? was 54.8%?Reduction of water cut was improved by rising rate of water injection,at the same time pressure gradient of injection was decreased.Ultimate recovery of heavy oil could be increased by changing water driving to steam driving,ultimate recovery of heavy oil increased largely with the rising of temperature,and temperature of steam driving was higher than water driving,ultimate recovery of steam driving under 200? was 58%,and exceed to 67.5% under 274 ?.Results on driving experiments of viscosity reduction agents shows,performances of 3# surfactant were better,such as viscosity reduction,compatibility,absorption and so on,and ultimate recovery was about 40%,the reasonable concentration was 0.3%,and reasonable injection volume was 0.5PV.Ultimate recovery of foam driving achieved highest,which was 27.67%,when injection volume was 0.45 PV,and ratio of gas and fluid was 1:2.Recovery of foam generated by CO2 was relatively high,which was 45.83%.However recovery of flue gas driving for heavy oil was low,ultimate recovery was obviously improved when converted to wasted water/flue gas alternative injection,and effects was better than only wasted water or flue water driving,and when gas and fluid was 1:2,recovery of water/flue gas alternative injection exceeded to 32.3%.The optimal ratio of mixing injection was selected by analyzing different combination of slugs,which provides guidance to production of oilfield combined with practical situation,showing great importance for EOR.