致密砂岩气藏孔尺度水锁机制及助排剂浓度优选  

Pore scale water locking mechanism and concentration optimization of drainage aids in tight sandstone gas reservoirs

作　　者：柳雪青 马立涛[1] 刘成[1] 葛岩[1] 熊俊杰[1] 刘登科 LIU Xueqing;MA Litao;LIU Cheng;GE Yan;XIONG Junjie;LIU Dengke(CNOOC Energy Development Co.,Ltd.,Tianjin 300452,China;Habitat College of Xi'an Jiaotong University,Xi'an Shaanxi 710049,China)

机构地区：[1]中海油能源发展股份有限公司,天津300452 [2]西安交通大学人居学院,陕西西安710049

出　　处：《石油化工应用》2023年第1期65-70,共6页Petrochemical Industry Application

摘　　要：致密气藏入侵流体造成的水锁伤害是气藏开发的重要制约因素,由于致密气藏孔喉细小且非均质性极强,造成该类气藏水锁伤害的微观机理及解水锁优选方法依然认识不清。基于此,本文利用核磁共振手段,开展了不同孔喉结构、不同助排剂浓度的驱替-渗吸实验,结果表明:平均孔喉半径越大,滞留流体越少,T_(2)谱>100 ms对应的孔喉优先返排;孔喉非均质性是影响返排效率的重要微观指标,毛管力反转效应是造成返排效率受阻的重要因素,该效应与气藏润湿性直接相关;添加助排剂能有效辅助返排,0.3%浓度对应的返排效率最高,对强水湿强非均质性气藏效果尤为显著,高黏度封堵效应造成低返排效率。本次通过开展不同助排剂浓度梯度的渗吸-驱替实验,揭示了水锁微观制约因素,制定了不同微观特征及不同润湿程度气藏助排剂添加标准的参考依据,为现场气藏水锁伤害评估及解水锁优选方法提供了理论支撑。The water lock damage caused by the invasion fluid of tight gas reservoir is an important restrictive factor for gas reservoir development.Due to the small pore throat and strong heterogeneity of tight gas reservoir,the micro mechanism of water lock damage and the optimization method of water lock removal are still unclear.Based on this,the displacement imbibition experiments with different pore throat structures and different concentration of drainage aids were carried out by means of NMR.The results show that the larger the average pore throat radius is,the less the retained fluid is,and the pore throat corresponding to T_(2) spectrum>100 ms has priority to flow back.Pore throat heterogeneity is an important micro index affecting flowback efficiency.Capillary force reversal effect is an important factor that hinders flowback efficiency.This effect is directly related to the wettability of gas reser voirs.The addition of flowback aids can effectively assist flowback.The flowback efficiency corresponding to the concentration of 0.3%is the highest,especially for strong water wet and strong heterogeneous gas reservoirs.The high viscosity plugging effect causes low flowback efficiency.This time,through the imbibition displacement experiment with different concentration gradients of drainage aid,the micro constraints of water lock are revealed,and the reference basis for adding drainage aid to gas reservoirs with different micro characteristics and different wetting degrees is formulated,which provides theoretical support for on-site gas reservoir water lock damage assessment and water lock removal optimization method.

关 键 词：助排剂 水锁 孔隙结构 润湿性 致密砂岩 

分 类 号：TE357.12[石油与天然气工程—油气田开发工程]