海上生物礁灰岩油藏水驱油特征分析

Analysis of Water-oil Displacement Characteristics in Offshore ReefLimestone Reservoir

生物礁灰岩储层内部微观结构复杂,可归纳为相对致密型、致密裂缝型、孔洞裂缝型和孔隙孔洞型四类储层,其水驱油特征尚不明确。采用短岩心、长岩心、全直径等实验分析方法,明确了不同岩心尺度、不同储集体类型下水驱油特征。研究表明,受微观非均衡驱替现象影响,大孔道易水淹,岩心水驱油实验含水率呈“厂”字形上升的形态;随着渗流空间尺度增大,非均质性增强,驱油效率有降低的趋势。研究结果可以为油藏尺度的渗流机理与开发动态特征分析提供科学依据。

The internal microstructure of reeflimestone reservoirs is intricate,classifiable into four categories based on complexity:relatively tight,tight-fractured,porous-fractured,and pore-porosity reservoirs.However,the water-oil displacement characteristics in reeflimestone reservoir remain unclear.Therefore,employing experimental analysis methods such as short cores,long cores,and full-diameter test,we elucidated water-oil displacement characteristics under different core scales and reservoir types.The study reveals that,influenced by microscopic non-equilibrium displacement phenomena,large pores and channels are susceptible to water saturation.In core water-oil displacement experiments,the water saturation rapidly rises,reaching a high level and maintaining consistently.As the permeability spatial scale increases,enhanced heterogeneity leads to a diminishing trend in oil displacement efficiency.These research findings provide a scientific basis for analyzing percolation mechanisms and dynamic development characteristics at the reservoir scale.