热致形状记忆“智能”型堵漏剂的制备与特性实验

裂缝性漏失是钻井工程中的世界性难题,具有裂缝开度不明确、堵漏效率低等特点。传统的桥接堵漏材料对裂缝开度敏感性较强,难以实现有效的自适应架桥封堵。基于形状记忆智能材料学科新进展,利用"热-机械变形"基本原理,研制了不同粒径的热致形状记忆智能型堵漏剂（密度为1.16 g/cm³）,借助傅里叶红外光谱仪、差示扫描量热仪和"折叠-展开"形状记忆测试方法,实验评价了其分子结构、玻璃化转变温度和形状记忆性能;测试了高温高压条件下颗粒膨胀及力学性能;开展了长裂缝封堵模拟实验,探讨了裂缝封堵机理。结果表明,热致形状记忆堵漏剂的玻璃化转变温度可依据漏层温度进行调控（72.86~102.35℃）,形状固定率和回复率大于99%;高温高压条件下（120℃、20 MPa）颗粒D90增长率大于40%,激活后抗压强度高,有利于在裂缝中自适应架桥封堵。热致形状记忆堵漏剂激活前为片状,易进入裂缝,达到激活温度后膨胀至立方体块状的三维结构,在一定范围内可自适应匹配漏层裂缝宽度,封堵效率高,采用一套封堵工作液配方即可成功封堵3~5 mm不同开度共存裂缝,实现温敏、自适应、高效封堵作用。

Preparation and characteristic experiments of intelligent lost circulation materials based on thermally shape memory polymer

Lost circulation in fractured formation is a worldwide problem in drilling engineering, with the characteristics of unclear crack opening, low plugging efficiency, and etc. The traditional bridging materials for treating lost circulation are sensitive to crack opening, and it is difficult for them to achieve effective adaptive bridging plugging. Based on the new development of the shape memory intelligent materials discipline, the paper develops thermally stimulated shape memory intelligent lost circulation materials (density:1.16 g/cm³)with different particle sizes using the basic principle of "thermal-mechanical deformation", and experimentally evaluates its molecular structure, glass transition temperature and shape memory performance using Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter and the test method of folding-expanding shape memory. The particle expansion and mechanical properties under high temperature and high pressure conditions were also tested. Through the simulation experiment of long fracture plugging, this study explores the fracture-plugging mechanism. The results show that the glass transition temperature of the thermally stimulated shape memory plugging agent can be adjusted according to the temperature of leakage zone (72.86~102.35℃), with the shape fixed rate and recovery rate greater than 99%. Under high temperature and high pressure conditions (120℃/20 MPa), the growth rate of D90 particles is more than 40%. After activation, D90 particles have high compressive strength, and thus are beneficial to the adaptive bridging plugging in fractures. The small stimulated shape memory plugging agent have a flaky shape before activation, easy to enter the fracture. After reaching the activation temperature, it expands to become a cubic massive 3D structure, and can adaptively match the width of fractures in the leakage zone within a certain range, showing high plugging efficiency. Using a set of formula of plugging fluid, it can successfully plug 3-5 mm coexisting fractures with different opening, achieving temperature-sensitive, adaptive and high-efficiency plugging.