碳酸盐岩井眼酸化解卡液技术研究

四川盆地元坝地区的超深水平井在钻井过程中卡钻大多发生在利用酸与泥饼中碳酸盐岩岩屑反应生成了可溶性盐类CaCl₂、MgCl₂，溶蚀破坏卡住钻具的泥饼结构。碳酸盐岩井段，提高该类地区浸泡解卡液解卡的成功率意义重大。为此，研究了酸基解卡液在高温条件下的解卡机理，优选出缓释剂、铁离子稳定剂等酸化解卡液的主要处理剂，形成了抗高温酸化解卡液体系，并对其酸化效果、酸化最佳时间、与隔离液配伍性、对钻具强度的影响等方面进行了评价。在高温、保证现场安全和保护储层的前提下，酸化解卡液对碳酸盐岩屑及含岩屑水基钻井液泥饼酸溶率达到40%，在元坝地区阆中2井配合工程解卡中取得了明显效果。同时，研究并率先评价了酸基解卡液对钻具强度的影响、浸泡作用的最佳时间，对浸泡酸化解卡的安全性及有效性给出了具体结论，具有参考意义。

Acid-based downhole drilling spotting fluid for carbonate gas wells in the Yuanba Area,Sichuan Basin

Pipe sticking most often occurs in the well section through carbonate formation in ultra deep well drilling in the Yuanba Area, Sichuan Basin. Thus, it is of great significance to facilitate the release of stuck pipe by soaking the stuckbreaking fluid in this study area. The pipe sticking will be released by soluble salts like CaCl₂, MgCl₂ which can be generated from the reaction between acids and carbonate debris in mud cakes. In view of this, the mechanism of stuck breaking is first analyzed under high temperature for the acid based downhole drilling spotting fluid. Then, the sustained release preparation, ferric ion stabilizer, etc. are optimized for this downhole drilling spotting fluid with high temperature resistance. Furthermore, evaluation tests are made for this newly developed acid based spotting drilling fluid on its acidizing result, best acidizing time, compatibility with spacer, impact on the strength of drilling tools, etc. In actual application, on the premise of high temperature, reservoir protection and safe field operation, the acid solubility of this fluid system for the carbonate debris and water based drilling mud cake reached up to 40%; an obvious stuck breaking result was achieved in the Langzhong 2 well in this study area. Meanwhile, the best time of soaking and the impact of this fluid system on the strength of drilling tools are studied and evaluated for the first time, the detailed results of which are provided for the safety and feasibility of this downhole drilling spotting fluid.