The Feasibility Study Of Binary Flooding (PHAM/Surfactant) And Polymeric Surfactants Flooding On Gaotaizi Oil Layer In The Saertu Oilfield

Gaotaizi reservoir is characterized by multiply layers, thin intervals, highcalcium content and rich mud. After a more than20years development, its residualoil saturation comes down dramatically; its water cut carries on rising, and itswater-flushed degree diversifies seriously. It is necessary to explore new effectiveenhanced oil recovery technology aiming to further develop such reservoir. Thereis no report on experiment developing such reservoir with enhanced oil recoverytechnology. Aiming the characters of Gaotaizi reservoir, polymeric surface-activeagents and surfactant/polymer systems are evaluated by lab experiments to screensuitable polymeric surface-active agent, its concentration and surfactant/polymersystems’ optimal formula and to determine its adaptability. Compared with HPAMsolution in same concentration, physical simulation experiments on artificial andnatural cores and surfactant/polymer system numerical simulation are conducted.From physical simulation experiments, polymeric surface-active agent’s optimalinjection parameters and optimal surfactant/polymer system formula aredetermined to achieve maximum control on different permeability degree. Withnumerical simulation, history fit of water flooding and index prediction of floodingprograms with water, polymeric surface-active agent and surfactant/polymersystem are conducted on the base of reserves fit. Lab experiments of performanceevaluation show that polymeric surface-active agent III and surfactant/polymersystem match well with oil and water in Gaotaizi reservoir. In physical simulationexperiments, for rocks with permeability degrees of200×10-3μm~2and600×10-3μm~2, on the same injection parameters, the enhanced oil recovery ratesdiffer little for ordinary polymers with medium molecular weight,surfactant/polymer system or polymeric surface-active agent. For the permeabilitydegree of200×10-3μm~2, the optimum parameters of injection of polymericsurface-active agent are content of800mg/L, injection slug of0.8PV; for thepermeability degree of600×10-3μm~2, the optimum parameters of injection ofpolymeric surface-active agent are content of1000mg/L, injection slug of0.8PV.All tested agents are sorted in descending order according to enhanced oil recoveryrate, which are22.0%for polymeric surface-active agent of type III,20.9%forsurface-active agent type RMA-1with content of0.3%,18.6for surface-active agent type HLX with content of0.3%and14.2%for ordinary polymers withmedium molecular. The optimum program to get a maximum enhanced oilrecovery rate is the ordinary polymers with medium molecular with the content of2000mg/L and the injection amount is0.8PV. The optimum program to get ahighest enhanced oil recovery rate with one ton agent is the ordinary polymers withmedium molecular with the content of1000mg/L and the injection amount is0.6PV.The optimum program with and comprehensive consideration of enhanced oilrecovery rate and economic benefit is the surfactant/polymer system with theinjection amount of600mg/L.PV~800mg/L.PV, with which we get an enhancedoil recovery rate7to7.5percentage point higher than that of pure polymer agent.Both physical simulation and numerical simulation show that both thesurfactant/polymer systems with two different types of surface-active agents withcontent of0.3%have better enhanced oil recovery rates than those with agents withcontent of0.2%on the same injection conditions, and on the same content ofagents, the surfactant/polymer system compounding with surfactant of RMA-1hasa better enhanced oil recovery rate than that of system compounding withsurfactant of HLX.