The Chemical Flooding Enhancing Oil Recovery Research Of Hejian Dongying High-temperature Reservoir

This paper is about chemical flooding enhancing oil recovery research for the hightemperature(90℃) and serious heterogeneity（V_k=0.79）of Hejian Dongyingreservoir.Firstly,through laboratory experiments,the flooding system suitable for theHejian Dongying reservoir conditions was screened,and a laboratory evaluation wasmade to the filter-outed flooding effects of the flooding system by the core floodingexperiment.Secondly,by using numerical simulation technique,screened floodingsystem was further optimizing designed on the basis of the indoor study.Indoorexperimental results shows that the best system of the surfactant aqueous flooding issurfactant CDS-1, the concentration of0.05%. Under the conditions of HejianDongying reservoir when the concentration of surfactant CDS-1is in the range of0.01%to0.30%,interfacial tension can down to10-2mN/m order of magnitude which canmake a substantial increase in the oil displacement efficiency. Because of thehigh-temperature characteristics of the reservoir,the long-term stability of the polymerflooding and surfactant/polymer flooding is not ideal, so they don’t fit Hejian Dongyingreservoir. The study of the profile control system for the reservoir showed that thelong-term stability of the produced water system is relatively poor,however,the clearwater profile control system has a long-term stability which can meet the reservoirapplication. Best clear water profile control system is polymer HLD-13000mg/L,methenamine concentration of450mg/L,resorcinol concentration of300mg/L,oxalic acid concentration of100mg/L. Best clear water weak gel system is polymerHLD-1800mg/L,methenamine concentration of115mg/L,resorcinol concentration of50mg/L, oxalic acid concentration of180mg/L,and the viscosity is96mPa.s. Coreflooding experiments show that the injected slug of weak gel flooding getting to0.4pvis the best,which can enhanced oil recovery of11.1%OOIP, and the Surfactant/weakgel flooding0.3pv,which can enhanced oil recovery of17.8%OOIP.The results of numerical simulation and optimization design shows that:①Multi round profilecontrol+low concentrations surfactants (Profile control radius of10m, six monthsprofile control). The program implemented2677.3days, daily injected1073.021m~3,can make980469t incremental oil,get oil recovery of14.34%OOIP than waterflooding.②Surfactant/polymer flooding weak gel (Composite system slug0.25PV,weak gel protecting slug0.05PV). Daily injected804.766m~3,can make1112429t incremental oil,get oil recovery of16.27%OOIP than water flooding.The results show that Hejian Dongying reservoir is suitable for the application ofMulti round profile control+surfactant flooding and surfactant/weak gel floodingwhich can enhance oil recovery more than14%OOIP. This research provides a reliabletheoretical basis and implementation of programs for the oil recovery improvement ofhigh-temperature reservoir of the same type of chemical flooding.