暂堵剂图解优化新方法在钻井液设计中的应用

为使钻井完井液在井壁上形成超低渗透的泥饼,需要依据暂堵剂粒径与储层孔隙尺寸之间的匹配关系,寻找一种科学、合理的暂堵剂优选方法。国内外普遍采用的"1/3架桥规则"和屏蔽暂堵方法主要依据储层的平均孔喉直径优选暂堵剂的颗粒尺寸,这对均质储层较为有效,但难以有效封堵非均质储层中较大尺寸的孔喉。在研究连续颗粒堆积效率最大值原理、理想充填理论和d90规则的基础上,提出了一种暂堵剂颗粒图解优化的新方法,研发的配套软件能够快速、准确地根据储层孔喉尺寸的分布对具有不同粒径分布的暂堵剂产品按一定比例进行合理的复配组合,得到最优的粒径分布,指导钻井液的暂堵优化设计。现场应用表明,利用该方法优选出的复配暂堵剂钻井完井液能有效形成致密泥饼,封堵非均质储层中不同粒径的孔喉,有效阻止钻井液中固相颗粒和滤液侵入油气层。与传统方法相比,对储层岩样的侵入深度较浅(<2 cm),具有更高的岩心渗透率恢复率(>83%)与更低的突破压力梯度(1.05 MPa/m),储层保护效果显著。

The application of New Graphical Optimizing Method of Temporary Plugging Particle Size Distribution in Drilling Fluids Design

The creating mud cake with ultra-low filtration with drilling fluid requires the match between the pore throat size and the temporary shielding/plugging agents(TPA) particle size.A new scientific and reasonable TPA optimizing method is developed."1/3 bridging rule" and "temporarily plugging/shielding technology" mainly based on mean formation pore size works effectively for homogenous reservoir,while is difficult to seal large size pore throats in heterogeneous reservoir.Based on "the Maximum Packing Efficiency Principle","Ideal Packing Theory" and "the D90 rule",a new graphical method to optimize plugging particle size distribution was proposed,and the associated software was developed which can quickly and accurately select and recombine TPA with different particle size in a given proportion based on formation correlative parameters,such as pore throat size data.Field tests shown that drilling fluids and well completion fluids composed of optimized TPA can create fine mud cake effectively,seal pore throats with different size in heterogeneous formation.Consequently it can prevent the solid particles and filtrate of invasive fluids from entering formation.Compared with conventional temporary bridging method,this new method has smaller invasion radius(<2cm),and higher return permeability(>83%),a lower breakthrough pressure gradient(1.05MPa/m),and better reservoir protection.