红河油田长8致密储层渗吸采油影响因素分析及矿场应用

Main controlling factors of imbibition oil recovery technology and field application in Chang8 tight oil reservoirs in Honghe Oilfield

为进一步提高红河油田长8致密油藏渗吸采油效果,针对渗吸压力、储层岩石润湿性和油水界面张力范围调整等施工因素对渗吸采油效果影响规律不明确的问题,选取红河油田长8致密砂岩露头岩心,利用自行研制的高压渗吸实验装置,评价渗吸压力、储层岩石润湿性和油水界面张力等因素对渗吸效果的影响,并使用多元线性回归法对各影响因素进行相关系数计算。结果表明:增加渗吸压力能大幅提升渗吸采收率和渗吸速率,相比大气压条件下,增压0.5 MPa时,渗吸采收率增加7.40~10.76个百分点,渗吸速率提高1.39~1.81倍;同一块岩心中,通过逐级提升渗吸压力也能提高渗吸效果,当渗吸压力由0.5 MPa提升至3.0 MPa时,渗吸采收率提高了7.61个百分点;实验表明调整岩石润湿性比调整油水界面张力对影响渗吸效果更为显著,保持岩石润湿角50°,油水界面张力10^(-2)mN/m时,更有利于发挥二者协同作用;多元线性回归法计算各相关系数由大到小依次为渗吸压力、岩石润湿性和油水界面张力。该研究成果对优选致密油藏渗吸增效剂和优化施工参数具有指导意义。

In order to further improve the imbibition recovery effect of Chang8 tight reservoir in Honghe Oilfield,in view of the uncertain influence of imbibition pressure,adjustment of construction parameters such as reservoir rock wettability and oil-water interface tension range on imbibition recovery effect,the core of Chang8 tight sandstone outcrop in Honghe Oilfield was selected.Experiments with self-improved high pressure imbibition device were carried out to study the influence of imbibition pressure,wettability of reservoir rock and oil-water interfacial tension on the imbibition effect.The results show that increasing the imbibition pressure can greatly improve the imbibition recovery and imbibition rate.Compared with atmospheric pressure,the recovery rate of imbibition increases by 7.40~10.76 percentage points and 1.39~1.81 times when the pressure is increased by 0.5 MPa.In the same core,imbibition effect can also be improved by increasing imbibition pressure step by step.When the imbibition pressure increased from 0.5 MPa to 3.0 MPa,the imbibition recovery rate increased by 7.61 percentage points.The experiment shows that adjusting rock wettability has more significant effect on imbibition than adjusting oil-water interfacial tension.When the wetting angle of rock is 50°and the interfacial tension between oil and water is 10^(-2)mN/m,the synergistic effect of oil and water is better.The weight of each influencing factor in descending order is imbibition pressure,rock wettability,oil-water interfacial tension.The research results have guiding significance for optimizing imbibition synergist and operation parameters in tight reservoirs.