特高含水期剩余油分类评价方法

Classification and evaluation method of remaining oil in ultra-high water cut stage

特高含水期剩余油分布日趋复杂,挖潜难度越来越大,明确剩余油开发潜力是特高含水期油藏提高采收率的基础。综合考虑特高含水期剩余油空间分布、富集程度、耗水特征及经济可动性,从剩余油可动用资源、区域可开发潜力等方面,提出了剩余油可动用系数以及剩余油可采潜力因子2个综合评价指标,构建了特高含水期剩余油分类评价综合指标集;在此基础上,利用Xie-Beni指数改进了模糊C均值聚类(FCM)算法,对特高含水期油藏剩余油进行无监督聚类评价,形成了特高含水期剩余油分类评价新方法。以孤岛油田西区北为例,开展了特高含水期剩余油分类评价以及挖潜调整研究。结果表明:该方法可精准确定剩余油潜力优势部位,针对孤岛油田西区北Ng3-4单元的各类剩余油潜力评价结果,分别提出了相应的挖潜措施,指导了单元层系井网互换转流线调整工作,措施调整后单元提高采收率2.1%,可采储量增加29×10^(4) t。

The underground distribution of remaining oil in the ultra-high water cut stage is growing complex,and it is more and more difficult to tap the potential.Clarifying the development potential of the remaining oil is the basis for enhanc⁃ing the oil recovery of reservoirs in the ultra-high water cut stage.Considering the spatial distribution,enrichment,water consumption characteristics,and economic mobility of the remaining oil in the ultra-high water cut stage,the recoverability coefficient and recoverable potential factor of the remaining oil were proposed from the aspects of recoverable resources of remaining oil and regional development potential to construct a comprehensive index set for the classification and evalua⁃tion of remaining oil in the ultra-high water cut stage.On this basis,the fuzzy C-means clustering(FCM)algorithm was im⁃proved by the Xie-Beni function to conduct an unsupervised clustering evaluation of the remaining oil in the ultra-high wa⁃ter cut stage.As a result,a new classification and evaluation method of the remaining oil in the ultra-high water cut stage was formed.With the north of the west area of Gudao Oilfield as an example,the research on classification,evaluation,and potential adjustment of remaining oil in the ultra-high water cut stage was carried out.The results show that this method can accurately determine the dominant position of the remaining oil potential.According to the evaluation results of various remaining oil potential of north Ng3-4 unit,corresponding potential tapping measures were proposed respectively,which guide the well pattern exchange and flow line adjustment between unit strata.After the adjustment,the recovery of this unit increases 2.1%,and the recoverable reserves increases 29×10^(4) t.