The Method Of Profile Control And Flooding In Low Permeability And Microcrack Reservoir Of Chang6Reservoir In Yong Ning

Chang-6oil reservoir in yongning area is fractured reservoir with low permeability. The oilfield is mainly waterflooding since it was developed. The existence of formation heterogeneity and fracture will lead to early waterbreakthrough between injection well and production well in most permeable zone.The result is that water cut of production well around is rising even waterflooding,reducing swept degree of injected water. Therefore, this oilfield needs sealing tiny cracks and fissures and the macroscopic throats, improving reservoir heterogeneity, changing the direction of streamline waterflood, improving sweep volume of injected water, so as to achieve the purpose of enhancing oil recovery.According to geological condition and development status of Chang-6oil reservoir in yongning area,this paper made a in house study about gel profile of low permeability reservoir with gel tiny cracks.First,from a polymer selection to research of gel and analysis of influence of gel,then evaluated temperature resistance and salt resistance and shear resistance and long term stability of gel.At last we carried core How test to make comprehensive evaluation of scaling ability and abrasionresistancc and profile modification and etc.The findings indicate that:①The water salinity of Chang-6oil reservoir in yongning area is62995.6mg/L. chloride calcium type;②Association polymer in yongning area has obvious viscosify ability, temperature resistance and salt resistance and shear resistance and shear recovcry.so we choose association polymer to do experiment for gel:③The optimum formulation of association polymer compound with formation water is as flows: association polymer is3000mg/L. cross linking agent is1200mg L. oxalic acid is mg/L;?Thc gel has temperature resistance,the best rang between40~60C.lt has obvious salt resistance.the proper water salinity between20000～100000mg/L Reserve rate of viscosity will be beyond84%after4months;⑤The gel can seal crack and high permeability reservoirs, seal ratio of above96%⑥By injecting gel can significantly improve oil displacement efficiency in the core. We can improve oil displacement efficiency by13.6%with0.3PV.In combined core experiments with different permeability contrast (5.14～45.4). We can improve oil displacement efficiency by2.7～38.3%by injecting gel;⑦Gel and11"surfactant can coexist, and at the same time use both of them the effect will be better.