水力裂缝内支撑剂输送沉降行为数值仿真

NUMERICAL SIMULATION OF THE PROPPANT TRANSPORTATION AND SETTING IN THE HYDRAULIC FRACTURE

研究支撑剂在裂缝内沉降运移规律对压裂施工设计及压裂井产能计算具有重要意义。建立欧拉-欧拉两相流模型,利用Fluent商业软件对支撑剂在三维裂缝内的沉降运移情况进行数值仿真,模型考虑压裂液的湍流效应、颗粒间的相互作用等因素。利用该模型研究不同施工参数(排量、压裂液黏度和砂比)、支撑剂性质(支撑剂粒径、支撑剂密度)对砂堤形态影响,并对裂缝壁面粗糙度、注入位置、支撑剂分级注入及顶替液注入等因素进行研究。结果表明:排量、压裂液黏度、支撑剂密度、支撑剂粒径及压裂液注入位置等因素对支撑剂展布形态的影响较大;支撑剂分级注入有利于改善压裂施工效果;压裂施工时,需要警惕过度顶替带来的不利影响;尾注可以改善近井筒地带裂缝充填效果。

The researches of the proppant transportation and settling in the fracture are important for the fracturing treatment design and the productivity calculation of the fractured well. Euler-Euler two-phase flow model was established to numerically simulate the transportation and settling in the 3 D hydraulic fracture with the help of Fluent Software. The turbulent effect and the particle-particle interaction were considered in the model for the fracturing liquid. By means of the model,the influences of the different operating parameters（ the discharge rate,fracturing fluid viscosity and proppant concentration） and the proppant properties（ the proppant size and density） on the proppant bank configuration were researched,and moreover the factors such as the fracture surface roughness,injected location,proppant grading and displacing fluid injections were also studied. The achievements show that the influences of the flow rate,the fracturing fluid viscosity,the proppant density and size the injected location and so on are much more serious; the grading injection is prone to improve the effects of the fracturing operation; when the operation constructed,the disadvantageous influence of the excessive displacement should be vigilant; the end injection can enhance the fracture infilled effects near the borehole.