超低渗透油藏高温高压动态吞吐渗吸驱油实验

Experiment of high-temperature and high-pressure dynamic huff-n-puff imbibition displacement in ultra-low permeability reservoir

为了进一步提高超低渗透油藏水驱开发后的采收率,使用高温高压动态吞吐渗吸驱油实验装置对储层天然岩心开展了动态渗吸驱油实验,优选出了最佳的吞吐渗吸驱油参数,并将其成功地应用到矿场试验中。室内实验结果表明:当使用质量分数为0.5%的阴-非离子型表面活性剂YN-11溶液作为渗吸液时可以显著提高动态吞吐渗吸采收率,并且随着渗吸液注入量的不断增大,渗吸采收率逐渐增大,最佳注入量为0.4 PV;当驱替流速在0.05~0.10 mL/min时,渗吸采收率较高;随着岩心中裂缝开度的增大,渗吸采收率逐渐增大,矿场实践中应尽可能地增大裂缝开度;随着关井时间的延长,渗吸采收率逐渐增大,推荐最佳的关井时间为120 h;随着吞吐次数的增加,渗吸采收率增幅逐渐减小,最佳吞吐次数为3次。矿场试验结果表明,S区块内4口井采取动态吞吐渗吸驱油措施后,日产油量明显提升,平均含水率明显降低,增油效果显著。研究成果对超低渗透油藏的高效开发具有一定的指导意义。

In order to furtherly improve recovery after water flooding development of ultra-low permeability reservoir,dynamic imbibition displacement experiment is carried out on natural core from reservoir by using high-temperature and high-pressure dynamic huff-n-puff imbibition displacement experimental equipment to optimize huff-npuff imbibition displacement parameters with successful application in field test. Lab experiment shows that 0.5%anionic-nonionic surfactant YN-11 solution used as imbibition solution can significantly improve imbibition recovery of dynamic huff-n-puff,and imbibition recovery increases gradually with increase of imbibition injection volume,with optimal injection volume of 0.4 PV. Imbibition recovery is high when displacement flow rate is 0.05~0.10 mL/min. Imbibition recovery increases gradually with increase of fracture aperture in the core,and fracture aperture should be increased as much as possible in field practice. Imbibition recovery increases gradually with extension of shut in duration,with recommended optimal shut in duration of 120 h,and incremental imbibition recovery gradually decreases with increase of huff-n-puff times,with optimal 3 times of huff-n-puff. Field test shows that daily oil production of 4 wells in Block S is significantly increased after dynamic huff-n-puff imbibition displacement,with average water cut significantly reduced. The research has guiding significance for efficient development of ultralow permeability reservoir.