砂质碳酸盐岩储层重复酸化酸液体系的优选与应用

胜利油田桩120、桩121区块生产层系主要为ES2段,该层段由于地质沉积的特殊性,形成了以碳酸盐含量占50%左右,砂质成分占40%以上的特殊地层。认为该类储层的酸化增注应有别于常规砂岩和碳酸盐岩储层;确定了重复酸化酸液体系的优选原则,并在此基础上进行室内模拟试验研究,优选出了有机化学级达酸体系。该体系利用缓速剂在岩石表面的吸附,有机酸与碳酸盐反应平衡等机理,实现保护地层骨架,减少二次伤害,以及深度酸化的目的。针对回注污水主要由乳化油引起伤害的特点,采用有机溶剂前冲洗地层再酸化的技术进行施工。1997年9、10月在两区块各进行了1口井的先导性试验,酸化增注效果显著。

OPTIMIZATION AND APPLICATION OF ACID FLUID FOR REACIDIZING ZHUANGXI ARENACEOUS CARBONATE

The main pay zone of both Zhuang- 120 and Zhuang- 121 blocks in Shengli Oilfield is ES2. It is a special formation of 50% or so of carbonate and more than 40% of arenaceous composition, which formed as special geologic sedimentation. Therefore, the treatment of acidizing and inJection increase to this formation should be different from that to conventional sandstone or carbonate formations. Based on this, determined optlmlzing rules of acid fluid system for reacidizing, conducted simulation study in lab, chose optimally organic chemical retarded acid fluid system. By means of the mechanlsms such as retarded agent adsorption on the surface of rock, reaction balance of organic acid and carbonate, etc., this system can protect formation framework, decrease second damage, and realize deep acidizing. Considering that reinjection of produced water bearing emulsified crude would result in formation damage, the formation was preflushed with organic solvent at first, and then acidized. Pilot tests of acidizing two wells in these two blocks were conducted in September and october respectively, and obvious effects had been observed.