Optimization Study On Chemical Flooding Methods To Enhance Oil Recovery For Chang-6Reservoir Of Yanchang

Low permeability reservoir occupies an important position in China’s petroleum industry,as an important oil industry resource over a period of time in future, which helps to increasereserves and production. High injection pressure, low natural oil production capacity and lowefficiency of water flooding are posed in injecting water, because of tight reservoir rock, smallporosity,thin throat, reservoir heterogeneity and high clay content. However surfactantflooding can reduce oil/water interfacial tension, change oil emulsification and rockwettability, decrease the adsorption of oil on rock and increase oil solubilization in water, sothat irreducible oil will be recovered and recovery efficiency will be improved.This article is intended for the reservoir rocks and reservoir fluids of the Chang-6reservoir of Yanchang. Among many varieties of surface-active agent, it was determined byinterfacial tension experiments and emulsifying property with oil that Changqing2thsurfactant was best with changqing crude systemThe molecular weight is determined by the experiment. The result shows that the middlemolecular weight is best for fracture permeability about100×10^-3μm². The best combinationsystem was chosen by the working performance test of combination system ang molecularsystem.The natural columnar cores come from different blocks in the Chang-6reservoir ofYanchang with permeabilities between0.92×10^-3μm²and1.47×10^-3μm². Surfactant floodingwas set up after water flooding. Laboratory findings indicate that waterflood recoveryefficiency of natural core is between17.71%and27.12%, surfactant flooding recoveryefficiency is between7.17%and9.15%. The effect is well. But waterflood recovery efficiencyof West15-6-147core is40.90%, it influences the action of surfactant in core, so surfactantflooding recovery efficiency is only5.71%and its effect is not well. In addition,using a highpermeability core and a low permeability core in parallel,inject polymer and surfactant indifferent volume by six ways,calculate the value of enhanced oil recovery,determine the bestin the six ways.The result is first inject0.1PV polymer into the core and then inject0.1PVsurfactant and reduplicate three times is the best way to enhanced oil recovery...