注水开发砂岩油藏优势渗流通道识别与描述

Identification and description of preferential percolation path for waterflooding sandstone reservoir

油田注水开发过程中受储集层非均质性、水油流度比、注采差异及注入水长期冲刷、剥蚀等影响,产生差异渗流,并产生优势渗流通道,进而形成大孔道,表现为注入水快速突进、高注入孔隙体积倍数、强水淹、高采出程度、高水油比等特征。大孔道的形成,对流体渗流起重要作用,影响并控制着剩余油分布,注入水大多从大孔道采出,水驱较弱的渗流区剩余油富集。因此,识别和预测优势渗流通道对寻找剩余油富集区具有重要意义。

In the process of oilfield waterflooding development, difference percolation occurs clue to the reservoir heterogenous characteristics, water-oil mobility ratio, injection-production intensity difference and long-term water washing, and the preferential percolation path gradually generates, finally forming macroscopic throats. This phenomenon is reflected on the rapid breakthrough of injected water, high injection pore volume, strong waterflooding, high ratio of total oil produced to OOIP, high water-off ratio and so on. The formation of large throats plays an important role in flow percolation, affects and controls on the distribution and formation of remaining oil. Remaining oil enrichment area is located in the low waterflooding section because of the mostly injected water producing from large throats. The identification and forecast of preferential percolation path are very important to find the remaining oil.