马岭油田北三区延10油层注水开发中储层伤害研究

A study on reservoir damage during waterflooding in Yan10 Reservoir of North-Ⅲ block, Maling oilfield

马岭油田北三区延10油层粘土矿物主要成份依次为伊利石、伊／蒙混层、高岭石、绿泥石,对储层的潜在危害依次为伊利石、伊／蒙混层和高岭石所造成的水敏和速敏。本文利用马岭油田北三区延10油层真实砂岩模型进行的伤害研究表明,1)马岭油田北三区延10油层存在弱速敏,临界速度的大小与渗透率呈正相关,一般渗透率越小,临界速度也越小。由于实际注入水的矿化度较实验用地层水的矿化度要低,故注水开发中的速敏伤害较实验结果要强。2)马岭油田北三区延10油层存在弱一中等程度的水敏,K+的存在和注入水盐度的提高会减轻水敏伤害的程度,注入水的盐度以5-10 g／L为宜。3)水敏伤害条件下的驱油效率较无水敏伤害条件下的驱油效率低11．35％,宏观波及系数也明显降低,从而降低了油层采收率。建议加强对马岭油田北三区延10油层注水开发中的储层保护研究,在注水开发中采取更有效的储层保护措施,以提高油层采收率。

In Yanl0 reservoir of North-Ⅲ block, Maling oilfield, the clay minerals are dominated by illite, mixed illite/smectite, kaolinite and chlorite. The potential damages to the reservoir are water and velocity sensitivities caused by illite, mixed illite/smectite and kaolinite. Based on reservoir damage study by using real sandstone model in the study area, the following understandings are achieved. （ 1 ） The velocity sensitivity of reservoir is weak in the study area, and the critical velocity is in positive correlation to permeability. The reservoir damage caused by velocity sensitivity is actually stronger than the experimental results, as the salinity of injection water is lower than that of the formation water used in the experiment. （2） The reservoir in the study area is characterized by weak-to-moderate water sensitivity, and the existence of K ^＋ and the increase of injection water salinity may alleviate reservoir damage from water sensitivity. The injection water salinity would be appropriate in the range from 5 to 10 g/L. （3） The oil displacement efficiency with water sensitivity damage is 11.35 % lower than that without water sensitivity damage, and the overall displacement efficiency also remark ably lowers, resulting in a lower recovery ratio.