优选暂堵剂粒度分布的新方法

为了实现屏蔽暂堵式钻井完井液能在井壁上形成渗透率接近零的泥饼,就要依据暂堵剂粒径与储层孔隙尺寸之间的最佳匹配关系,寻找出一种科学、合理的暂堵剂优选方法.阐述了优选暂堵方案的理想充填理论和d90规则.依据连续颗粒堆积理论所提出的理想充填理论对提高钻井液的暂堵效果具有指导意义,颗粒堆积效率越高,越有利于形成致密的泥饼,对储层的暂堵效果也越好.在此基础上提出了一种优选暂堵剂颗粒尺寸及其分布的图解新方法.依据该方法开发的配套软件能够根据相关地层参数,快速、准确地对暂堵剂产品进行合理的选择.实验结果表明,根据理想充填理论和d90规则建立的优选暂堵剂颗粒尺寸的图解新方法在原理上更加合理,优选出的复配暂堵方案能有效地形成致密泥饼,可达到十分理想的保护储层的效果,与传统方法相比,更有利于对中、高渗储层的保护.

Optimization of bridging particle size distribution of drilling fluid for formation protection

In this paper, methods and technologies for determining of the particle size of bridging agents are summerized, and the "Ideal Packing Theory" and the "D 90 Rule"are introduced also. The "Ideal Packing Theory" was put forward based on the "Dense Packing Theory", which has profound influence on increasing the temporary plugging efficiency. In this theory, the higher the packing efficiency is, the tighter the mud cake forms, and the better the plugging effect produces. A new graphical optimization of particle distribution for plugging agents was proposed, and a computed program was developed to select temporary plugging particles quickly and accurately. Experiments showed that the new graphic optimization method is more reasonable based on the "Ideal Packing Theory" and the "D 90 Rule "to select particles for temporary plugging agents, and it produces tight mud cake with ideal formation protection effect. The method is more suitble for protecting medium-high permeability reservoir compared with conventional methods.