渤海某区域边底水油藏高倍水驱机理及应用

渤海某砂岩油藏边底水能量强,采液强度大,密闭取心资料显示油田存在部分强水淹、洗油程度高等现象;基于此发现,开展了2000 PV高倍水驱油实验,明确了目标区块极限水驱特征;同时借助CT扫描成像驱替技术,开展了高倍水驱提高采收率机理研究;在明确高倍水驱机理基础上,借助数模对目标油田开发策略进行了研究。研究表明:含水率为98%时,岩心驱出程度平均值为32.4%,2000 PV极限驱替时,驱出程度平均值为63.9%,岩心中含油饱和度随注水倍数增加呈下降趋势;注入倍数越高,水相渗透率增加,两相共流区变宽,残余油饱和度减小;水驱倍数的增加,渗流场发生改变,波及体积扩大使得连片状残余油变少,总体剩余油饱和度不断降低;含水98.2%时进行提液,能够增油83×10⁴m³,采出程度可达到18.9%。

Mechanism and application of high-power waterflooding in a sandstone reservoir with side-bottom water in a certain area of the Bohai Sea

A sandstone reservoir in the Bohai Sea has strong bottom water energy,strong fluid recovery,and closed coring data show that there are some phenomena of strong water flooding and high degree of oil washing in the oilfield.Based on this finding,a 2000 PV high water flooding experiment was carried out to clarify the target block limit water flooding efficiency and oil-water two-phase percolation characteristics.Meanwhile,with CT scanning imaging flooding technology,research on the mechanism of high-power water flooding to improve oil recovery was carried out.On the basis of one-dimensional flooding experiments,the strategy of target oilfield was developed by means of digital simulation was studied.The research shows that,at a water content of 98%,the average value of core expulsion is 32.4%,and at 2000 PV limit displacement,the average value of expulsion is 63.9%.The oil saturation in the core decreases with the of water injection multiple.The higher the injection multiple,the higher the water phase permeability increases,the two-phase co-flow zone becomes wider,and the residual oil saturation decreases.As the water flooding multiple increases,the percolation field changes,and the expansion of the volume makes the continuous sheet-shaped residual oil less,and the overall remaining oil saturation is constantly decreasing.When the water content is 98.2%,the liquid extraction can increase 83×10⁴m³ of oil and the recovery can reach 18.9%.