论文总字数：26314字

摘 要

随着时代的发展以及经济的飞速增长，人们对物质生活的需求也越来越高，随之而来的对资源开采的量也在逐渐增大。作为“工业的血液”的石油的开采量也在逐步增多。国内大部分油田都进入中后期开采阶段，开采地层的深度的增加和条件的复杂化对固井材料提出新的要求。油井水泥作为固井基础材料，高性能化是当前趋势，优越的力学性能是油井水泥高性能化的一个重要指标。

镁盐晶须MMW作为一种单晶体纤维，尺寸只有几十个微米，比水泥颗粒还小，显微镜下表现为纤维状，兼具细填料和纤维双重功能，已经广泛用于塑料、树脂、建筑材料等领域。本文将探究镁盐晶须MMW对油井水泥的力学性能的影响。结果证明，镁盐晶须MMW对油井水泥力学性能的提高非常显著。

镁盐晶须对油井水泥密度和凝结时间几乎没有影响。水泥浆流动度随晶须掺量增加逐渐减少，为了使晶须在水泥浆体中分散均匀，添加适量减阻剂改善其流动度。综合镁盐晶须MMW的各力学性能参数，晶须最佳掺量为4%，在该掺量下，早期对油井水泥力学性能有较好的改善，后期对油井水泥力学性能改善效果略有降低。晶须对油井水泥抗压强度改善最为明显，较净浆水泥石抗压强度，7d提高了21.5%，28d提高了18.8%。此外，通过掺加硅灰（实验室所用）替代部分水泥，既能降低成本，又能分散晶须和进一步增强。单掺硅灰4%的抗压强度最高，但是后期抗压强度略有降低，确定复掺晶须和减阻剂的最终配比为 4%晶须（外掺） 4%硅灰（内掺） 5‰减阻剂 96%油井水泥，该复合体系抗压强度较净浆水泥石抗压强度7d提高了25.0%，28d提高了16.0%。本实验初步探索了单掺晶须及复掺硅灰和晶须的后期强度降低原因是晶须在碱性环境中长龄期形貌受影响，并解释了油井水泥中晶须的增强机制。

关键词：镁盐晶须MMW 油井水泥 力学性能 硅灰 固井

The effect of one magnesium salt whisker MMW on the mechanical properties of oil well cement

Abstract

With the development of the times and the rapid economic growth, the demand for material life of people becomes higher and higher, accompanying the mining of resources increasing. As "the blood of industry", petroleum is now being mined even more. Most domestic oilfields have entered the stage of middle or later exploitation. The increase of the oil well’s depth and the complicated conditions of oil well has put forward new requirements to the cementing material. As the cementing base material, oil well cement must be high-performance to catch up with current trends, and the superior mechanical property is an important index for high-powered oil well cement.

As one kind of the single crystal fiber, magnesium salt whisker MMW is only a few dozen microns. It is smaller than cement particles and characterized by fibrous under the microscope. It both has the functions of the filler and the fiber. It has been widely used in plastic, resin, building materials and other fields. This article will explore its effect on mechanical properties of the oil well cement. The result proves that magnesium salt whisker MMW has a significant improvement to the oil well cement.

The magnesium salt whisker almost has no effect on the density and setting time of the oil well cement. But the fluidity of cement paste will reduce with the increasing of whisker's proportion. To make the whisker spread evenly in the cement paste, we add a moderate amount of drag reducer to improve the cement’s fluidity. Synthetically compared with every mechanical property parameter of the magnesium salt whisker MMW, the best proportion of the whisker is 4%. This can improve the mechanical properties of oil well cement well in the early, while the improvement of the mechanical properties slightly lower in the late under the proportion. The improvement of compressive strength of the whisker to oil well cement's is the most obvious. Compared with the compressive strength of the net cement paste, it is increased by 21.5% in 7 days and 18.8% in 28 days. Besides, mixed with silica fume can both lower the cost and disperse the whisker to strengthen the cement by replacing part of the cement. The compressive strength of the oil well cement is the highest when the proportion of the silica fume is 4%. But the compressive strength also lowers in the late. Ultimately, we can be sure that the best proportion of the composite material is 4% whisker 4% silica fume 5‰ drag reducer 96% oil well cement. The compressive strength of this compound system is increased by 25.0% in 7 days and 16.0% in 28 days compared with the net cement paste. In this experiment, we explore the reason why the single doped whisker and double mixing silica including fume and whisker make the compressive strength lower in the late is that the morphology of whisker is influenced by alkaline environment for a long time. Meanwhile, it explained the reinforcing mechanism of the whisker in the oil well cement.

Key Words: Magnesium salt whisker MMW; Oil well cement; Silica fume; Mechanical properties; Cementing

摘要 I

ABSTRACT II

第一章 绪论 1

1.1晶须的概述 1

1.1.1晶须的定义和分类 1

1.1.2无机晶须的特性 2

1.1.3镁盐晶须MMW的基本物理性质 2

1.1.4镁盐晶须MMW的原料来源及制备方法 3

1.1.5镁盐晶须MMW的应用现状 3

1.1.6晶须作用机理 5

1.2固井的简介...............................................................................................................................6

1.2.1固井的概念 6

1.2.2固井现状及发展趋势 7

第二章 实验原料与实验方法 8

2.1主要原材料 8

2.2实验仪器 10

2.3油井水泥性能评定方法 10

2.3.1水泥浆的制备 11

2.3.2流动度测定 11

2.3.3凝结时间测定 11

2.3.4密度的测定 12

2.3.5抗压强度测定 12

2.3.6抗折强度和抗冲击强度测定 12

2.3.7线膨胀率测定 13

2.4本章小结 13

第三章 镁盐晶须MMW对油井水泥性能的影响 14

3.1碱性环境模拟实验 14

3.2镁盐晶须MMW对油井水泥力学性能的影响 15

3.2.1不同镁盐晶须MMW掺量对油井水泥初终凝、流动度和密度的影响 15

3.2.2不同镁盐晶须MMW掺量对油井水泥抗压强度的影响 17

3.2.3不同镁盐晶须MMW掺量对油井水泥抗折抗冲的影响 18

3.2.4最佳镁盐晶须MMW掺量对油井水泥线膨胀率的影响 20

3.2.5硅灰掺量优选及复掺晶须的抗压强度……………………………………..21

3.3镁盐晶须MMW在油井水泥中作用机理 25

3.4本章小结 26

第四章 结论与建议 28

参考文献 30

致谢 32

第一章 绪论

固井是将油井水泥、水和其他外加剂混合而成的浆体注入到地下井壁和套管间的环空，经过合适的时间凝结硬化而成水泥环的过程。其目的就是封隔地下油气水层，防止这些流体在地下发生层间串流并支撑保护套管，避免固井作业失败。随着石油工业的不断发展，浅层油气储量的矿井开采日益枯竭，深井、超深井的勘探开发已成必然，井下的复杂环境势必造成固井的成本急剧增加。

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