高温砂岩酸化微粒运移伤害物质来源与防治方法

塔里木油田大北-克深区块进行常规土酸酸化改造时使用盐酸作前置液防治钙、镁离子沉淀,却引发微粒运移,造成储层伤害。旨在剖析微粒运移伤害物质来源并提出相应的防治措施,分别从宏观和微观角度首次研究15%盐酸与黏土矿物在150℃下反应特征,包括溶蚀率测定、扫描电子显微镜(SEM)表征、电感耦合等离子体原子发射光谱(ICP-AES)分析及岩心驱替实验等。结果表明:(1)高温酸/岩反应过程中,氢离子置换了黏土矿物中的铝离子并生成水合二氧化硅;(2)结构受损的黏土矿物是发生微粒运移的物质来源;(3)自主研发螯合酸ZFJ-CA作前置液能够有效减轻对黏土矿物溶蚀,达到防治微粒运移目的。通过大量室内试验,首次揭示了盐酸与黏土矿物的高温反应特征,确定了微粒运移物质来源并对微粒运移实现有效防治,为矿场酸化改造提供了参考。

Cause of fines migration in high temperature sandstone acidizing and corresponding measures

Mud acid is commonly used in acidizing process to prevent the precipitation of Ca2+ and Mg2+ in Dabei-Keshen area of Tarim fields. However, fines migration is then triggered during this process, which severely damages the formation. The objective of this study is to investigate the cause of fines migration and put forward corresponding measures. In this study, the characteristics between 15%-wt HCl and clays at 150°C were firstly studied from both macro and micro perspectives, including dissolution tests, SEM analysis, ICP-AES analysis, core flooding tests, etc. The results were as follows: (1) Al3+ was extracted from clays during the process of reactions between HCl and clays and hydrated silicates was established as well; (2)Physically damaged clays whose Al-O octahedral structures were broken was the main cause of fines migration. (3) Self-developed chelating acid ZFJ-CA instead of HCl was effective to alleviate the dissolution ratio of clays, which successfully prevent fines migration. This study firstly reveals the characteristics between HCl and clays at 150°C, clarifies the cause of fines migration, realizes the prevention of fines migration, and further provides reference for field applications.