低渗砂岩储层正压射孔中水锁损害试验研究

Experimental Study of Water-Block from Overbalance Perforation in Low-Permeable Sandstone

低渗砂岩水锁损害已成为高效开发低渗透油气藏的一大技术瓶颈,因此,如何通过室内试验评价水锁损害显得尤为重要。国内外许多学者大都研究钻完井中"相对稳定"正压差或欠平衡钻井自吸作用造成的损害,忽视了正压射孔完井中瞬时附加压力对孔道水锁损害的影响。通过试验研究了在瞬时附加压力下东海地区低渗砂岩的水锁损害,结果表明,瞬时正压差可增加损害程度25%左右。根据低孔低渗透岩心水锁损害试验结果,提出了低孔低渗透气藏降低水锁损害的措施和建议。

Water-block damage to low permeability sandstone is the main obstacle for its high efficient exploitation;therefore it is important to evaluate water-block damage in laboratory.Most researches focus on the damage caused by positive differential pressure in overbalance drilling or imbibitions in underbalanced drilling.While the instantaneous abutment pressure in overbalance perforating which can cause serious water-block damage in porous channel are neglected.This paper investigates the water-block damage of low-permeability sandstone under the instantaneous abutment pressure using experiments.The results show that the instantaneous abutment pressure can increase the water-block damage by 25%,The suggestions were provided to reduce the water-block damage.