矿渣MTC处理废弃钻井液机理

Mechanism of disposing waste drilling fluid with slag MTC

废弃钻井液转化为水泥浆技术(MTC)是一种既满足环保要求又节约成本的好方法。为此进行了废弃钻井液成分分析、钻井液影响矿渣MTC性能等几方面的实验研究。结果表明:废弃钻井液的主要组成部分黏土中含有大量的Si O2物质,不仅能够与强碱反应生成活性Si O2,促进矿渣MTC凝固体胶结,还能够与矿渣中水泥熟料水化产物Ca(OH)2反应,生成力学性能更好的低C/S(CaO.Si O2分子比)比的C-S-H凝胶;矿渣MTC抗压强度随着钻井液加量的增加而增大,随着钻井液中纯碱量的增大而增大;钻井液中黏土水化程度越高,矿渣MTC强度越大;黏土12 h即可充分水化,矿渣MTC固井液的稠化时间变短,有利于提高固井液的防气窜效果,其耐高温性、耐酸侵蚀性更好。

Slag MTC is a unique cementing technique that drilling fluid is converted to cement slurry with the addition of blast furnace slag, and it is a cost effective and environmental friendly method. The component of waste drilling fluid was analyzed and the effects of drilling fluid on the performance of MTC was investigated. The experimental results show that abundant SiO2 is contained in the clay, the main component of waste drilling fluid. SiO2 can be hydrated and then generate active SiO2 under alkaline condition, which is helpful to the cementation of slag MTC. SiO2 can also react with Ca(OH)2 of hydrated product and generate C-S-H gel with low C/S ratio. The compression strength of MTC can be improved with the amount of drilling fluid increased; it can also be improved with more sodium carbonate added in drilling fluid. And the more sufficiently the clay hydrates, the stronger the compression strength of the slag MTC. The clay usually can hydrate sufficiently after 12h. The shortened thickening time of MTC cementing slurry will help improve the anti-channeling effects of the cementing slurry and allow it to work at higher temperatures and under acid corrosive environment.