Nano SiO₂-basalt Fiber Composite Cement-based Cementing Materials:Application To Thermal Reservoir Mining

In the mining process of geothermal resource thermal reservoirs,the performance of cement-based cementing materials in high temperature environment is the key to ensure cementing quality,which is directly related to the smooth progress of thermal reservoir mining.Aiming at the key technical problems of conventional cement-based cementing materials in fluidity control,high-temperature strength attenuation and brittle failure in thermal reservoir mining,systematic research on cement-based cementing material system for thermal reservoir mining has been carried out.Important engineering significance and scientific value.Based on the combination of theoretical analysis,experimental research and microscopic analysis,the research on nano-SiO₂-basalt fiber composite cement-based cementing material system for thermal reservoir mining is systematically carried out.Preferably,fly ash,nano SiO₂,basalt fiber,early strength agent and water reducing agent are comprehensively modified for G grade oil well cement,and developed excellent performance and convenient construction for different high temperature environments（100°C,150°C,200°C）The environmentally-friendly new high-temperature composite cement-based cementing material is systematically evaluated for its fluidity,setting time,stability,stone rate,high-temperature residual strength,toughness and deformation properties at high temperatures,using scanning electron microscopy（SEM）.The micro-features were analyzed by X-ray diffraction analysis（XRD）,and the mechanism of high temperature action was discussed to establish a systematic system for the thermal storage of nano-SiO₂-basalt fiber composite cement-based cementing materials..The main research results are reflected in the following aspects:（1）By comparing the basic properties of ordinary Portland cement（P.O 32.5R）and G-grade oil well cement at normal temperature and 100°C,it is found that the performance of ordinary Portland cement（P.O 32.5R）is better than that of ordinary Portland cement（P.O 32.5R）.Large,and more cracks occur at 100°C;and G-grade oil well cement has a more stable high temperature resistance,so it is used as a type of thermal cement reservoir cementing.In order to better adapt the cement-based cementing materials studied to the mining requirements of thermal reservoirs,it is preferred to modify the externally-mixed materials,nanomaterials,basalt fibers,water reducing agents and early strength agents with high temperature resistance.It lays a good foundation for the development of composite cement-based cementing materials for thermal reservoir mining.（2）Using the orthogonal test method,according to the requirements of the thermal reservoir mining under different temperature conditions for the performance of cement-based cementing materials,the thermal reservoirs at different temperatures（100°C,150°C and 200°C）were developed.Optimized formulation of SiO₂-basalt fiber composite cement-based cementing material.The performance evaluation results show that the three optimized formulations have good fluidity,stability,residual（compression,flexural,splitting and tensile strength）,mass loss,dynamic and static modulus ratio and compression ratio.Performance.（3）A single G-grade cement slurry,cement+fly ash（composite slurry）,composite slurry+nano-SiO₂ by microscopic analysis combined with scanning electron microscopy（SEM）and X-ray diffraction analysis（XRD）.The composite slurry+basalt fiber and optimized formula were used to analyze the microscopic characteristics of the composite.The high temperature mechanism of the nano-SiO₂-basalt fiber composite cement-based cementing material in thermal reservoir mining was discussed.The analysis results show that the synergistic effect of fly ash,basalt fiber,nano-material and early strength agent promotes the high-temperature mechanical properties of cement-based cementing materials,and the suitable water-solid ratio and suitable water-reducing agent ensure the cement-based solidification.Well materials have good comprehensive properties such as high temperature flow properties.On this basis,a high-temperature hydration process model of nano-SiO₂-basalt fiber composite cement-based cementing material for thermal reservoir mining was constructed.The research results provide theoretical basis and scientific basis for the study of the influence of high temperature environment on the performance of cement-based materials.It provides a new solution to solve the problem of cementing technology in thermal reservoir mining,and also works on cement-based composite materials of other similar projects.Research has reference and reference value.