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

作者：Yang Fei^*; Peng Shangping; He Zhiqiang; Zhang Hao

来源：Natural Gas Industry, 2013, 33(1): 95-100.

DOI：10.3787/j.issn.1000-0976.2013.01.016

• Down-hole drilling
• Sichuan Basin
• Strength
• Ultra deeps
• Yuanba areas

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, MgCl2which 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% s an obvious stuckbreaking 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.

• 出版日期2013