钻井液泥饼形成及评价研究综述

钻井过程中钻井液滤失形成地层浅处的内泥饼和井壁表面的外泥饼。形成高质量泥饼可以保证顺利钻进,但也对后期固井和生产造成影响。介绍了泥饼的形成过程和结构特征,调研了泥饼形成的数值模拟研究和实验研究,总结了泥饼评价的常规方法和参数计算经验公式。内泥饼和外泥饼的形成是同时进行、相互影响的过程;目前的研究多局限于外泥饼的形成和评价,且评价结果因技术人员经验和主观认识而有较大差异;研究中通常忽略内泥饼的形成及其对外泥饼的影响。未来研究需要综合考虑影响泥饼形成的地层因素和钻井液因素;基于"数字岩心"技术,研究泥饼的颗粒、孔隙与喉道特征;建立泥饼形成的数值模型,研究各因素对泥饼形成的影响规律。从微观结构揭示泥饼形成机理,并建立泥饼评价方法,对钻井液滤失造壁性能评价和体系优选、评价泥饼对固井质量的影响等工作有重要的意义。

Review on formation mechanism and evaluation method of mud cake in drilling fluid

During drilling, the drilling fluid is filtered to form the inner mud cake at shallow stratum and the outer mud cake at well wall. The formation of high-quality mud cake can ensure smooth drilling, and also has an impact on later cementing and production. The formation process and structural characteristics of mud cake were introduced, the numerical simulation and experimental study of mud cake formation were investigated, and the conventional methods of mud cake evaluation and empirical formula of parameter calculation were summarized. The formation of inner mud cake and outer mud cake is a simultaneous and interactive process. At present, the research is mostly limited to the formation and evaluation of outer mud cake, and the evaluation results are quite different due to the experience and subjective understanding of technicians. The formation of inner mud cake and its influence on outer mud cake are usually ignored in research. In the future research, the formation factors and drilling fluid factors that affect the formation of mud cake need to be considered comprehensively. The characteristics of particles, pores and throat of mud cake can be studied based on the "digital core" technology. A numerical model of mud cake formation should be established to study the influence of various factors on mud cake formation.It is of great significance to reveal the formation mechanism of mud cake from microstructure and establish the evaluation method of mud cake, so as to evaluate the wall-building performance of drilling fluid filtration, optimize the system and evaluate the influence of mud cake on cementing quality.