scholarly journals Hybrid Effect of Wollastonite Fiber and Carbon Fiber on the Mechanical Properties of Oil Well Cement Pastes

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianglin Zhu ◽  
Jiangxiong Wei ◽  
Qijun Yu ◽  
Mingbiao Xu ◽  
Yuwei Luo

Oil well cement is a type of natural brittle material that cannot be used directly in cementing operations. Fiber is a type of material that can effectively improve the strength and toughness of cement stone, and hybrid fiber materials can more effectively improve the performance of a cement sample. To overcome the natural defects of oil well cement, the new mineral fiber, i.e., wollastonite fiber, and common carbon fiber were used in oil well cement, and the micromorphology, mechanical properties, and stress-strain behavior of the cement were evaluated. The experimental results show that carbon fiber and wollastonite fiber are randomly distributed in the cement paste. The mechanical properties of the cement paste are improved by bridging and pulling out. The compressive strength, flexural strength, and impact strength of cement stone containing only carbon fiber or wollastonite fiber are higher than those of the pure cement, but too many fibers are not conducive to the development of mechanical properties. A mixture of 0.3% carbon fiber with 6% wollastonite fiber in oil well cement slurry results in a greater increase in compressive strength, flexural strength, and impact strength. In addition, compared with blank cement stone, the strain of the mixed cement stone increases substantially, and the elastic modulus decreases by 37.8%. The experimental results supply technical support for the design of a high-performance cement slurry system.

2016 ◽  
Vol 847 ◽  
pp. 445-450 ◽  
Author(s):  
Ming Li ◽  
Fei Meng ◽  
Xiao Yang Guo

The effect of graphite oxide (GO) on the mechanical properties of oil well cement was experimentally studied, in view of the zonal isolation failure due to the brittleness. The microstructure of cement stone was observed by SEM, and the mechanism of graphite oxide reinforced cement stone was also investigated. The result illustrates that the mechanical properties of cement was improved significantly due to the addition of GO. When the GO dosage was 0.05%, the compressive strength, flexural toughness, and splitting tensile strength of cement paste at 7 day age were increased by 61.32%, 15.46% and 145.34% respectively. GO had no bad effect on the application properties of cement slurry, and the stability of the slurry was favorable. Besides, GO could reduce the fluid loss of cement slurry. When GO reinforced cement stone undergoes damage under complex stress, if damage occurs within graphite oxide layer, chemical bonds of GO layers must have been broken, and the force between the layers of GO must be overcome when interlaminar peeling happens, which will lead large amounts of energy consumption as well. The mechanical properties of the cement stone were enhanced by the above two aspects. The research results can provide a theoretical reference for solving the brittle fracture of oil well cement stone.


2018 ◽  
Vol 916 ◽  
pp. 200-204 ◽  
Author(s):  
Hui Ting Liu ◽  
Jian Zhou Jin ◽  
Yong Jin Yu ◽  
Shuo Qiong Liu

The improvement of strength and ductility is a challenging task for application of oil well cement. As a 2D nanomaterial with high strength and toughness, graphene oxide (GO) was used as a reinforcing additive in oil well cement. The mechanical properties and micro-structure of oil well cement enhanced by GO were investigated. The compressive strength and flexrual strenghth of cement stone both showed a good enhancement effect when the content of GO was 0.02% -0.05%. The compressive strength and flexrual strength could increase by 15.8% and 33.5%, respectively. The results of SEM and MIP revealed that GO played a template role in promoting the formation of hydration products and further filled in the pores between the hydration products, which refined the micro-structure and improved mechanical properties of the cement consequently.


2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Miao He ◽  
Jianjian Song ◽  
Mingbiao Xu ◽  
Lei He ◽  
Peng Xu

Oil well cement is a brittle material, which can not ensure the long-term sealing integrity of oil and gas wells when used in cementing operations directly. As a kind of polymer emulsion material, epoxy resin emulsion has a bright future for improving the properties of the cement slurry. Epoxy resin emulsion was added to oil well cement and its workability and mechanical properties were studied, the stress-strain behavior of cement samples was evaluated, and the microstructure was observed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show the epoxy resin emulsion used in oil well cement will affect the fluidity, but the rheological property of cement slurry with different content of resin meets the construction requirements. The resin reduces the water loss of cement paste and has no adverse effect on the thickening time. The compressive strength of cement stone decreases with the increase in resin content. When the content of resin is 6%, the flexural strength and impact strength of the cement sample are the largest, and 50.7% and 20.2% higher than that of the specimen without resin, respectively, after curing for 28 days. Further comparison shows that epoxy resin emulsion can improve the mechanical properties of oil well cement better than styrene-butadiene rubber latex. Meanwhile, the resin obviously improves the deformability and decreases the elastic modulus of cement stone. Compared with pure cement, resin cement slurry has no extra hydration products, but the formation of hydrated calcium silicate is inhibited. The microstructure shows that the resin forms a polymer film in the cement matrix and interweaves with cement hydration products, thus improving the flexibility of cement paste.


2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jianjian Song ◽  
Mingbiao Xu ◽  
Weihong Liu ◽  
Xiaoliang Wang ◽  
Peng Xu ◽  
...  

The surface hydrophilicity of thermoplastic rubber (TPR) is poor, and the effect of using it directly in oil well cement is not good. TPR was modified by different silane coupling agents, and the hydrophilicity of the modified TPR was studied by Fourier-transform infrared (FT-IR) spectroscopy and dispersion stability photography. The application effect of modified TPR in oil well cement slurry was also evaluated. The fracture surface morphology of TPR cement stone was observed by macrophotography and scanning electron microscopy (SEM). The results demonstrated that the hydrophilicity of TPR particles was improved after modification with silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH570), and its application effect in cement slurry was excellent. Compared with the pure cement paste, the compressive strength of the cement paste with addition of TPR modified by KH570 was reduced, but the flexural strength and impact strength of the cement paste were effectively enhanced. Moreover, the modified TPR greatly improved the deformation capacity and decreased the elastic modulus of the cement paste. The modified TPR particles formed a plastic polymer network structure in the cement stone and penetrated the cement hydration products, filling in the cement paste to form a flexible structural center. Thus, it improved the mechanical properties and reduced the brittleness of cement paste.


2014 ◽  
Vol 692 ◽  
pp. 433-438 ◽  
Author(s):  
Jing Fu Zhang ◽  
Jin Long Yang ◽  
Kai Liu ◽  
Bo Wang ◽  
Rui Xue Hou

Carbon dioxide CO2could corrode the oil well cement paste matrix under agreeable moisture and pressure condition in deep oil wells, which could decrease the compressive strength and damage the annular seal reliability of cement paste matrix. The problem of oil well cement paste matrix corrosion by CO2was researched in the paper for obtain the feasible corrosion prevention technical measures. The microstructure and compressive strength of corroded cement paste matrix were examined by scanning electron microscopeSEMand strength test instrument etc. under different corrosion conditions. The mechanism and effect law of corrosion on oil well cement paste matrix by CO2were analyzed. And the suitable method to protect CO2corrosion in deep oil wells was explored. The results show that the corrosion mechanism of cement paste matrix by CO2was that the wetting phase CO2could generate chemical reaction with original hydration products produced from cement hydration, which CaCO3were developed and the original composition and microstructure of cement paste matrix were destroyed. The compressive strength of corrosion cement paste matrix always was lower than that of un-corrosion cement paste matrix. The compressive strength of corrosion cement paste matrix decreased with increase of curing temperature and differential pressure. The corroded degree of cement paste matrix was intimately related with the compositions of cement slurry. Developing and design anti-corrosive cement slurry should base on effectively improving the compact degree and original strength of cement paste matrix. The compounding additive R designed in the paper could effectively improve the anti-corrosive ability of cement slurry.


2019 ◽  
Vol 944 ◽  
pp. 1103-1107
Author(s):  
Ming Dan He ◽  
Ming Li ◽  
Yong Jin Yu ◽  
Hao Wang ◽  
Wei Yuan Xiao ◽  
...  

To adequately understand the waterborne epoxy resin and enhance the compressive, tensile strength of oil-well cement stone, the cement composite materials were prepared with different addition of waterborne epoxy resin, and the specimens were cured for 3days, 7 days, 14days, 28days at 50°C thermostatic water bath to test the compressive strength and tensile strength, respectively. The results showed when the content of resin emulsion is 30%, the compressive strength and tensile strength of the cement are increased by 303.09% and 306.04% compared with pure cement, respectively. Obviously, in the mechanical performance testing, oil-well cement stone modified by waterborne epoxy resin have been significantly improved compared with the pure cement. To explore the enhanced microstructure of oil-well cement modified with waterborne epoxy resin, the cement specimens were prepared with 30% waterborne epoxy resin analyzed by scanning electron microscopy (SEM).


2012 ◽  
Vol 229-231 ◽  
pp. 95-99 ◽  
Author(s):  
Yu Wang ◽  
Yu Feng Chen ◽  
Yan Lu ◽  
Hui Fang Zhang ◽  
Zhi Guo Sun

On the basis of analyzing the oil well cement corrosion mechanism by SO42- and HCO3-, the corrosion products, microstructure and compressive strength of cement stone were measured and the changing regularity and influence factors of compressive strength were analyzed under different experimental conditions. The following conclusions can be drawn. Under the interactive corrosion effect of SO42- and HCO3-, Ca(OH)2 in cement stone was dissolved out and consumed, the calcium silicate hydrate was decomposed, ettringite, gypsum, calcite and thaumasite were produced which destroyed the structure and components of cement stone primary products and led the compressive strength of corrosion cement stone decline. With the increases of ion concentration of corrosive solution, temperature and corrosive time, the compressive strength was decreased gradually, even collapsed completely.


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