Formation mechanisms of fracture plugging zone and optimization of plugging particles  

作　　者：LEI Shaofei SUN Jinsheng BAI Yingrui LYU Kaihe ZHANG Shupei XU Chengyuan CHENG Rongchao LIU Fan 

机构地区：[1]School of Petroleum Engineering,China University of Petroleum,Shandong Qingdao 266580,China [2]CNPC Engineering Technology R&D Company Limited,Beijing 102206,China [3]Petroleum Engineering School,Southwest Petroleum University,Chengdu 610500,China

出　　处：《Petroleum Exploration and Development》2022年第3期684-693,共10页石油勘探与开发（英文版）

基　　金：Supported by National Natural Science Foundation of China(51991361,52074327);Major Engineering Technology Field Test Project of CNPC(2020F-45)。

摘　　要：As formation mechanisms of plugging zone and criteria for fracture plugging remain unclear,plugging experiments and methods testing granular material mechanical properties are used to study the formation process of the plugging zone in fractured formations,analyze composition and ratios of different sizes of particles in the plugging zone,and reveal the essence and driving energy of the formation and damage of the plugging zone.New criteria for selecting lost circulation materials are proposed.The research results show that the formation of the plugging zone has undergone a process from inertial flow,elastic flow,to quasi-static flow.The plugging zone is composed of fracture mouth plugging particles,bridging particles and filling particles,and the proportion of the three types of particles is an important basis for designing drilling fluid loss control formula.The essence of the construction of the plugging zone is non-equilibrium Jamming phase transition.The response of the plugging zone particle system to pressure is driven by entropy force;the greater the entropy,the more stable the plugging zone.Lost circulation control formula optimized according to the new criteria has better plugging effect than the formula made according to conventional plugging rules and effectively improves the pressure-bearing capacity of the plugging zone.The research results provide a theoretical and technical basis for the lost circulation control of fractured formations.

关 键 词：fractured formation drilling fluid loss plugging zone plugging mechanism plugging particles optimization criterion 

分 类 号：TE28[石油与天然气工程—油气井工程]