特低渗透油藏超前注水效果影响因素实验

EXPERIMENT OF THE INFLUENCING FACTORS OF THE ADVANCED WATER INJECTION IN EXTRA LOW PERMEABILITY OIL RESERVOIR

特低渗透油藏超前注水开发方式具有良好的开发效果.以大庆油田外围特低渗透油藏扶余油层为研究对象,研究了超前注水的合理压力保持水平、渗透率、应力敏感性和启动压力梯度对开发效果的影响.结果表明：特低渗透油藏超前注水的合理地层压力水平应当保持在原始地层压力的120％左右,超前注水初期产液量高、见水早,但对含水率上升有一定抑制作用;储层渗透率越低,最终采收率提升的比例越大,在能够注入的前提下,渗透率越低越适合超前注水开发方式;扶余油层在超前注水开发方式下渗透率恢复率提升4.35％ ～ 12.71％,能够有效克服低渗透储层应力敏感性损害;超前注水开发方式能够通过恢复地层压力和克服应力敏感性综合影响启动压力,在现场试验的大井距下能够大幅降低启动压力,减小注水井的工作压力.因此,采用超前注水开发方式开发外围特低渗透油藏扶余油层具有较好的效果.

Much better development effects have presented for the method of the advanced water injection in extra low permeability oil reservoirs.Taking Fuyu layers in Daqing peripheral oilfields with the extra low permeability reservoirs as studying objects,the reasonable water injection pressure maintained level and influences of the permeability,stress sensitivity and start-up pressure gradient on the development effects are conducted.The results show that the level should be kept at about 120％ of the original,the initial injection is characterized by high liquid production,earlier water breakthrough and a certain inhibitory watercut rise;the lower the reservoir permeability is,the greater the proportion of the ultimate recovery factor will be,on the premise of the available water injection,the lower the permeability is,the more suitable for the advanced water injection;under the conditions of the advanced water injection,the permeability recovery rate is up to 4.35％ ～ 12.71％ for Fuyu oil layers,thus the stress sensitivity damage of the low permeability reservoirs can be effectively overcome;with the help of the recovered formation pressure and overcome stress sensitivity,the start-up pressure can be comprehensively influenced,in the field tests of large well spacing,the start-up pressure can be reduced,and furthermore the operating pressures of the water injectors is also significantly decreased.Therefore,the advanced water injection has become one of the much better developing approaches in Fuyu extra low permeability reservoirs of Daqing peripheral oilfields.