英南2井储层伤害评价及保护措施研究

Evaluation of reservoir damage of Well Yingnan-2 and its protection measures

英南2井在钻探完井后产量明显下降,储层受到了严重的伤害,需要进行储层伤害评价及保护措施的研究。通过对储层岩性物性、孔隙结构及黏土成分进行分析的结果表明,储层孔隙喉道细小,且存在大量的伊蒙间层矿物,容易导致较为严重的敏感性伤害。在此基础上,进行了水锁和各种敏感性伤害实验评价,结果表明,水锁、水敏以及压敏是储层的主要伤害因素。设计了一种预防水敏伤害的钾基聚合物钻井液体系,对黏土矿物起到了稳定作用,静态伤害实验结果表明岩心渗透率恢复率较高,更有利于保护储层;针对英南2井储层水锁程度强的特点,采用了CO2泡沫压裂技术进行压裂,同时在生产过程中控制地层压力在合理的范围内。各种措施效果较好,可大面积推广应用。

The output of Yingnan-2 well declines obviously after drilling,as well as the reservoir is seriously damaged.Therefore,it is necessary to evaluate reservoir damage and conduct research on protection measures.The analysis results of lithology,physical properties,pore feature,and clay components of reservoirs show that pores and throats are tiny and there is plenty of andreattite,which easily lead to serious sensitivity damage.Based on latent damage factors,the author runs water lock and different sensitive experiments.Results show that water lock,water sensitivity,pressure sensitivity are the main damage factors.A potassium base sulphonated polymer drilling fluid formulation is designed for preventing the water sensitivity damage.The static performance of the cores damaged shows that the permeability restoration of the cores is high.CO2 fracturing technique is suggested to be used,and formation pressure should be controlled appropriately.