开展压裂液伤害性研究对于低渗透储层压裂开发具有重要的指导意义。结合低磁场核磁共振岩心分析技术和常规岩心流动实验方法,深入研究了低渗储层压裂过程中压裂液的水锁伤害、固体残渣堵塞伤害以及敏感性伤害。实验结果表明:岩心由于可动孔隙中水相滞留引起的水锁平均伤害率为23.4%;由于压裂液破胶形成的固体残渣堵塞对储层的平均伤害率高达66.1%,且储层越致密,孔喉越细小,伤害程度越高;同时对于水敏或碱敏严重的储层,通过优化压裂液配方,可将由于储层敏感性所导致的伤害率降至10%以下。利用核磁共振横向弛豫时间(T2)谱分析技术,实现了储层伤害的微观定量描述,并首次建立了与宏观渗透率伤害率的联系。
To evaluate formation damage of fracturing fluid has important guiding significance for developing low permeable reservoirs. Combined with core analysis by low magnetic field NMR and conventional core flooding experiments,it was studied on formation damages of water- block,plugging of solid residue,and sensitivity in fracturing process of low-permeable reservoir. Results indicated that because of movable retained water in pores,the average damage rate of water blocking was 23. 4%; the average damage rate of solid residue plugging after gel breaking can reach to 66. 1%,and then the tighter the reservoir and the smaller the pore throat are,the higher the formation damage is. For serious water or alkali sensitive formation,the damage rate of sensitivity can be decreased to below 10% by optimizing fracturing fluid formula. By using the NMR T2 spectrum technology,the formation damage can be described quantitatively at the microscopic level. And relationship between microscopic and macroscopic damage rate of permeability was established for the first time.