储集层孔喉网络场演化规律和剩余油分布

以胜坨油田二区沙二段第8砂组第3小层的三角洲储集层为例,研究了长期受到开发流体浸泡、驱动的储集层的孔喉网络场的演化机理和演化规律及其与微观剩余油形成和分布的关系.研究结果表明,储层孔喉网络演化是由油藏开发流体动力地质作用所造成的,孔喉网络场的演化是动态的、持续发生的,孔喉网络场总的演化规律是:颗粒点、线接触关系减少;孔喉连通程度提高,喉道分选性变好;粘土矿物减少,各类粘土矿物相对含量变化;岩石颗粒的润湿性向亲水转化.孔喉网络场的演化控制和影响了剩余油分布,并建立了特高含水率开发阶段微观剩余油的4种分布模式.

Evolvement of reservoir pore-throat-net and remaining oil distribution

Water-flooding is the main method for oilfield development in the eastern China.The reservoirs for a long-term water-flooding development can be lixiviated and scoured continually by the injected fluid.The clay,seepage,pore throat and rock framework of reservoirs will be changed dynamically after a long-term water flooding,which may cause the complex pattern of remaining oil distribution.Taking the data of a delta reservoir in the third layer of eighth group of second member of Shahejie Formation in Shengtuo oilfield,the pore-throat-net evolvement law and mechanism of the reservoir lixiviated and scoured by developed fluid over a long period were investigated.The relationship between variety of microscope reservoir and micro remaining oil distribution was also analyzed.The results show that the pore-throat- net evolvement was caused by dynamical geological process of developed fluid in the reservoir and also took place dynamically and continually.The general laws of evolvement show the following features:①The point and line contacts of grains decreased;②The communication degree of pore with throat increased.The grading of pore and throat got meliorative;③The total content of clay was reduced;④The wettability of rock trended to hydrophile.The distribution of remaining oil in reservoir was controlled and affected by the pore-throat-net evolvement.Four types of distribution modes for micro remaining oil in the development stage of reservoir with supper high water-cut were built up.