姬塬地区长4+5油藏砂体接触关系及对油藏水驱效果的影响

Contact modes of sandstone and its influence on water flooding effect of Chang 4+5 reservoir in Jiyuan area

姬塬地区长4+5油层组发育交错叠置的水下分流河道砂体,其内部接触关系复杂,严重影响该区油藏分布规律及水驱开发效果。开展长4+5油藏单砂体界面识别划分、剖析砂体接触关系及其对油藏水驱开发效果影响的精细研究,有利于姬塬地区长4+5油藏的持续稳产及高效开发。基于单砂体界面的识别划分标志,综合应用岩心分析、测井及生产动态资料,精细刻画砂体内部接触关系,进而厘清砂体横向交错与垂向叠置关系对油藏水驱开发效果的影响。结果表明:姬塬地区长4+5油藏砂体垂向叠置关系有切叠式、叠加式和分离式3类,其中切叠式砂体较均质,含油性好,水驱动用程度高,其次是叠加式砂体;单砂体的侧向接触关系可分为侧切式、对接式和孤立式3类,不同接触关系反映了河道砂体井间连通程度的差异,进而影响油井注水见效周期,其中侧切式接触关系对应的油井注水见效时间短,其次为对接式、孤立式单砂体所对应的油井见效不明显。

The interlaced underwater distributary channel sand bodies are developed in Chang 4+5 reservoir group in Jiyuan area,and their internal contact relationships are complex,which seriously affects the reservoir distribution law and water flooding development effect in this area.It is beneficial to the sustained and stable production and efficient development of Chang 4+5 reservoir in Jiyuan area by the fine study of identification and division of single sand body interface,analyzing the contact modes of sand bodes and their influence on water flooding effect in Chang 4+5 reservoir.Based on the identification and division of the single sand body interface,the core,logging,and dynamic production data are comprehensively applied to delineate the internal contact relationships of sand bodies,and then clarify the influence of transverse cross and vertical superposition relationships of sand bodies on water flooding effect.The results show that there are three vertical superposition relationships of sand bodies in Chang 4+5 reservoir in Jiyuan area,namely cut-stacked,superimposed,and separated.Among them,the cut-stacked sand bodies are more homogeneous,with high oil content and percentage of producing reserves under water flooding,followed by the superimposed sand body.The lateral contact modes of single sand bodies can be divided into three types:isolated mode,docking mode,and side-cut mode.Different contact modes reflect the difference in interwell connectivity of channel sand bodies,which in turn affects the effective time of water injection in oil wells.The effective time of water injection in oil wells corresponding to the side cut mode is short,followed by the docking mode,and the effect of water injection in oil wells corresponding to the isolated sand body is not obvious.