Study On The Weak ASP Experiment For The Second Order Reservoir Of The East Fault Block In Beiyi District

In Daqing oil field since the 80 s,much of research on ASP flooding and effects of recovery were mainly conduct.Now four major field tests of alkali ASP flooding have been completed.With the application of ASP flooding technology in the development of the second class reservoir,the permeability of layers becomes lower,and the difference of interlayer is bigger.Because of the big contradictions between layers,much more layers,and complex structure of layers and so on,injecting ability test,optimization of ASP flooding slug,chromatographic separation and dynamic detention tests are needed.Based on two and three class reservoir in Daqing oilfield,laboratory experimental research on matching relationship among polymer molecular weight,concentration and core permeability is conduct,and drag coefficient,residual resistance coefficient and other parameters of ASP are calculated.Through physical simulation experiment of ASP flooding,size of main slug and auxiliary slug,and concentration of various chemicals are optimized,in order to determine the optimal size of main slug and auxiliary slug,and concentration of slug.Using long enough natural rock cores,physical simulation displacement experiments are conduct under the condition nearly close to the reservoir,to observed phenomenon of chromatography,and determine relative parameters of components of ASP system.Results show that when the degree of viscosity degradation of ASP system affects the highest injection pressure,if permeability is constant,the greater the degree of viscosity degradation is,the lower the injection pressure become.Permeability affects the highest injection pressure of ASP system,when degree of viscosity degradation keep constant,the lower the permeability is,the higher the injection pressure will become.And when viscosity is the same,amount of polymer with low molecular weight is larger,and it is less able to reduce water phase permeability.But polymer with high molecular weight can cause core plugging.Considering the practical situation of the second class reservoir permeability,So ASP system of polymer with 16 million molecular weight is proposed to be used for injection,and the viscosity of ASP system before shear is 50 m Pa·s.Applying the rock cores relative to features of actual reservoirs in oil displacement to optimize size and concentration of slug,the optimum main slug and its concentration is [1.2wt%Na2CO3+0.3wt%surfactant +2200mg/L polymer]0.35 PV,and the concentration of auxiliary slug is [1.0wt% Na2CO3+0.1wt%surfactant+2200mg/L polymer]0.15 PV.Through dynamic detention tests of ASP system in natural casting core,it is determined that retention volume of alkali is 0.31 mg/g,retention volume of surfactant is 0.1 mg/g,and retention volume of polymer is 0.051 mg/g of polymer,retention volume of alkali is biggest.Combining with the measured results,components of ASP system are obtained.It is concluded that phenomenon of chromatographic separation appears when weak base/ASP compound system is injected.And when ASP system flows through the model,chromatographic separation happens among polymer,alkali and surfactant.Polymer breaks through at first,then alkali and surfactant break through together.Complex pore structure of second class reservoir could increase the degree of the chromatographic separation.