东河油田C_Ⅲ油组低渗储层的伤害及改造

Damage and Acidizing of the Low Permeability Formation in Donghe Oilfield C_Ⅲ

东河油田CⅢ油组为低渗透油藏,层数多、单层厚度薄、黏土矿物种类多、物性差异大、非均质性严重。在钻完井、采油、注水、增产作业等过程中,储层污染严重,导致注水压力高、注水量低。分析认为储层岩矿组成复杂、孔喉结构差、敏感性强、岩石表面亲油、钻完井液流体以及不合理的增产工作液是储层损害的主要原因。针对储层特点及伤害机理,通过实验优选了(CH3OCH2CH2)2O溶解泥浆堵塞物,0.3%CTAB+0.1%B-1改变岩石亲油润湿性、降低储层吸水压力,6%HCl+6%SA602+6%SA702多氢酸为主体的解堵剂体系。该体系的解堵率为85.8%,解堵后的岩石抗压强度伤害率为18.0%,对岩石骨架的伤害小。DH1-H15井的现场应用表明,多氢酸解堵酸化后的吸水指数从1.18 m3/(d.MPa)增至22.50 m3/(d.MPa),解堵效果明显好于有机土酸和氟硼酸。

The reservoir of Donghe Oilfield was low permeability formation with the features of multiple layers,thin single layer,complex lithology and serious aeolotropies.During the construction of drilling,completion,production,water injection and stimulation,the formations were seriously damaged which induced higher injection pressure and lower injection rate.The key factors of damage were complex lithology,poor pore throat,drilling completion fluid and unreasonable stimulation fluid,et al.Based on the formation characteristics and damage mechanism,（CH3OCH2CH2）2O was selected to dissolve mud,0.3% CTAB and 0.1% B-1 was used to change the rock wettability,and 6% HCl＋6% SA602＋6% SA702 acid solution as low damage,deep penetration plug removal agent.Experiment results showed that the remover rate of this system was of 85.8%,and the percentage damage to rock compressive strength was of 18.0%.The injury to rock skeleton was little.This technology was used in DH1-H15 well.The water injectivity index increased from 1.18 m3/（d · MPa） to 22.50 m3/（d · MPa）.The removing efficiency of multi-hydrogen acid system was much better than that of organic mud acid and fluoroboric acid.