储层温度条件下一步酸体系优选新方法

A New Method for Optimizing One Step Acid System under Formation Temperature

曹 冲 钟岳宸 周福建 薛艳鹏 李 源 姚二冬

CAO Chong ZHONG Yuechen ZHOU Fujian XUE Yanpeng LI Yuan YAO Erdong

一步酸体系优选方法基于常温条件，往往无法真实、动态地反映储层温度条件下的实际情况，导致优选体系在残酸环境下依旧产生氟化物沉淀，对其应用造成一定困难。针对这一问题，在络合滴定法的基础上提出一种以螯合值为指标、夹逼准则为基础的一步酸液体系优选的新方法。测定了土酸、螯合酸1数 4# 5种酸液体系对Ca2+、Al3+、Fe3+、Si4+ 4种金属离子的螯合能力，比较了土酸和优选的螯合酸注入岩心后对岩心渗透率的影响和岩心的伤害情况。结果表明，在25、60、80、90℃条件下，螯合酸4#对4种金属离子均有较好的螯合效果。在25、60、90℃下岩心经螯合酸4#处理后的渗透率分别是处理前岩心的1.68倍、3.14倍、9.21倍；经土酸处理后的岩心产生明显的二次沉淀，而螯合酸4#处理后的岩心无二次沉淀产生，验证了优选酸化液体系方法的可靠性。该方法可模拟不同地层温度条件下酸液体系中金属离子的实时反应动态，可真实地再现砂岩酸化液体系的二次沉淀问题。

At present，the existing one-step acid system optimization method was based on room temperature condition，and oftencould not reflect the actual condition under the dynamic reservoir condition in real，which resulted in many preferred systems still producing fluoride precipitation in the residual acid environment，etc. Based on the complexometric titration method，a new method for chelating acid system based on the chelation value and the clamping criterion was proposed. The chelating abilities of five kinds of acid systems，including mud acid and chelating acid 1—4#，to four metal ions Ca2+、Al3+、Fe3+、Si4+ were studied. The effects of mud acid and preferred chelating acid on the permeability and damage of core were compared. The results showed that chelating acid 4# had the best capability of chelating four kinds of metal ions at 25，60，80 and 90℃. The permeability of the core after treatment with chelating acid 4# at 25，60 and 90℃ was 1.68，3.14 and 9.21 times than that of the core before treatment，respectively. The results of core morphology after acid treatment showed that the mud acid had a secondary precipitation after treatment，and there was no obvious secondary precipitation after chelating acid 4# treatment，which further proved the reliability of the preferred acidification system method. This method could simulate the real-time reaction dynamics of metal ions in acid system under different formation temperature conditions，and truly reproduce the secondary precipitation problem of sandstone acidizing liquid system.

10.19346/j.cnki.1000-4092.2019.03.015