多尺度无机晶须增强油井水泥基材料及机理研究

发布时间：2018-03-11 13:39

本文选题：油井水泥　切入点：硅质晶须　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：在油气井工程中,水泥环性能是影响后续钻进与油气开采的关键因素。随着目前油气勘探开发向深部、低渗透、海洋、非常规油气藏的延伸,油气井对水泥环的性能要求也越来越高。水泥环这一水泥基材料属于脆性材料,抗压强度与弹性模量较高,抗拉强度较低,破坏时体现出较为明显的脆裂特征,在井下易产生大量微裂纹,造成水泥环层间封隔能力下降,水泥环完整性受到破坏。因此,基于水泥环的微观结构对其进行增韧对提高水泥环层间封固能力具有重要意义。论文在调研前人研究成果的基础上,根据水泥石微裂纹萌生、扩展的尺度效应提出采用不同尺寸的晶须材料对水泥石进行力学改性。论文研究了直径500nm,长度集中于10-30μm的A类硅质晶须、直径0.5-2.5μm,长度集中于200-300μm的B类硅质晶须单种掺入以及二者混杂掺入对水泥石力学性能的影响。结果显示二者均可显著改善油井水泥石的力学性能。其中,1%掺量的A类硅质晶须水泥石试样的28d抗压、抗拉及抗折强度相较于纯水泥试样分别提高了 9%、104%及26%,并且试样的极限应变超过5%,相较于纯水泥试样提高了约194%,弹性模量为4648.4MPa,相对于纯水泥试样降低了31.1%;2%掺量的B类硅质晶须水泥石的28d抗压、抗拉及抗折强度相对于纯水泥试样分别提高了19%、100%及34%,试样的极限应变达到了4.2%,相较于纯水泥试样提高了约147%,弹性模量为5429.3MPa,相对于纯水泥试样降低了19.5%;1%掺量的A类晶须与2%掺量的B类晶须混杂增强水泥石试样的28d抗压、抗拉及抗折强度相对于纯水泥试样分别改善了 21%、129%及42%,极限应变为6%,相对于纯水泥试样提高了约253%,弹性模量为4027.6MPa,相比于纯水泥试样降低了约40.3%,表现了良好的多层次增韧效果。水泥环完整性评价实验结果表明A类晶须、B类晶须与混杂晶须均有效提高了水泥环完整性。对水泥石试样进行了 XRD测试分析、红外光谱分析、压汞孔隙分布测试、扫描电镜观察等测试,探讨了不同尺度晶须对水泥石的增韧机理。测试结果表明不同尺寸的硅质晶须均不影响水泥石的水化过程与水化产物;SEM观察发现,尺寸较小的A类硅质晶须表面附着有水化产物,与基体结合较好,在裂纹萌生、扩展初期通过桥连、偏转以及拔出效应等增强水泥石力学性能;尺寸较大的B类硅质晶须与水泥石基体结合界面较A类硅质晶须要差,通过自身较大的接触面积,在裂纹扩展过程中与基体拉扯、摩擦耗散能量,最终达到增强基体的目的;当上述两类晶须混杂掺入时,不同尺寸的硅质晶须在裂纹扩展的不同阶段进行阻裂,协同增强基体,实现增强作用的尺寸梯度,更为有效地提高了水泥石试样的力学强度。研究结果表明,A类硅质晶须与B类硅质晶须均可有效改善油井水泥石的力学性能与微观结构,二者混杂体现了良好的多尺度增韧效果。研究结果对油井水泥石增韧及水泥环完整性维持有一定的指导意义和应用价值。
[Abstract]:In oil and gas engineering, cement performance is a key factor affecting the subsequent drilling and exploitation of oil and gas. With the development of oil and gas exploration to deep, low permeability, ocean, extension of unconventional oil and gas reservoirs, oil and gas properties of cement are increasingly high requirements. The water base mud cement the material is a brittle material, compressive strength and elastic modulus of high tensile strength, low failure shows obvious brittle fracture characteristics in the underground, easy to produce a large number of micro cracks, resulting in cement interlayer isolation ability of cement decreased, destruction of integrity. Therefore, the microstructure of the toughened cement is of great significance to improve the cement fixation capacity of sealing layer. Based on the research in this paper based on the results of previous studies, according to the initiation of cement micro cracks, expansion of scale effect is proposed with different sizes of whisker material force on the cement Study of modification were studied in this paper. The diameter of 500nm, length from 10-30 m a silicon whisker diameter of 0.5-2.5, m, B concentration in 200-300 siliceous whisker length m single doped and two incorporated effects on mechanical properties of cement pastes. The results showed that the mechanical properties of the two can be significantly improved oil well cement stone. Among them, a siliceous cement compressive whisker specimens with 1% dosage of 28d, the tensile and flexural strength compared with pure cement samples were increased by 9%, 104% and 26%, and more than 5% specimens of ultimate strain, compared to the pure cement sample is increased by about 194%, the elastic modulus is 4648.4MPa, relative in the pure cement sample decreased by 31.1%; the dosage of 2% B compressive siliceous cement 28d whisker, tensile and flexural strength compared to pure cement samples were increased by 19%, 100% and 34%, the ultimate strain samples reached 4.2%, compared to the pure water mud sample increased About 147%, the elastic modulus is 5429.3MPa, compared to pure cement samples decreased by 19.5%; enhance the compressive cement specimens of 28d hybrid B whisker whisker and a 2% volume 1% content, the tensile and flexural strength compared to pure cement samples were improved by 21%, 129% and 42%, the limit is 6%, compared to pure cement sample is increased by about 253%, the elastic modulus is 4027.6MPa, compared to the pure cement sample is reduced by about 40.3%, the performance of multi-level toughening. Cement integrity evaluation showed that a B whisker, whisker and hybrid whiskers can improve the cement integrity of cement stone. Samples XRD test analysis, infrared spectrum analysis, mercury intrusion pore distribution test, SEM observation, discussed the mechanism of different scale Whisker Toughening on cement stone. Test results show that the different size did not affect the cement silica whisker The hydration process and hydration products of stone; SEM observed that a smaller siliceous whisker surface attachment of hydration products, combined well with the matrix, the crack initiation, propagation through early bridging, deflection and extraction effect enhanced mechanical properties of cement stone; a larger size of B whiskers siliceous and cement stone the substrate interface is a silicon whisker to poor, through its own large contact area, and pulled the matrix in the crack propagation process, friction energy dissipation, and ultimately achieve the purpose of enhancing the matrix; when the two kinds of whisker incorporated, different stages of different sizes of siliceous whisker in the crack propagation of crack resistance, synergy enhance the matrix, enhance the size gradient effect, effectively improve the mechanical strength of the cement stone samples. The results showed that the class A and class B siliceous siliceous whisker whisker can effectively improve the strength of cement stone The two properties of microstructures show good multi-scale toughening effect. The research results have guiding significance and practical value for toughening of oil well cement and cement ring integrity.

【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.75

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