固井用高镁废渣微膨胀水泥浆体系

Microdilatant High Magnesium Slag Cement Slurry

高镁废渣是一种与矿渣性质完全不同的特种固体废弃物。利用等温量热(ICT)和XRD分析了高镁废渣掺量为40%的油井水泥浆体及其硬化体组成,在80℃水浴养护条件下的早期强度不高,但后期强度超过净浆。针对其低早强的特点,研究了不同掺量早强剂对掺渣水泥浆体抗压强度的影响,确定早强剂最佳掺量为3%、降失水剂最佳掺量为1.5%,最终形成高镁废渣微膨胀水泥浆体系。80℃下该水泥浆体系膨胀性能、抗压强度和孔径结构的测试结果表明:其1 d、28 d和90 d的线膨胀率分别为0.006 2%、0.045%、0.061%;1 d抗压强度为18.2 MPa,后期强度超过净浆;掺渣水泥石和净浆水泥石90 d孔隙率分别为22.99%和25.47%,且前者中有害孔数量小于后者,与抗压强度测试结果相吻合;同时高镁废渣微膨胀水泥浆体系的综合性能满足固井施工要求。

High magnesium slag is a kind of special solid waste that is quite different than mineral waste residue in nature. Study on a cementing slurry treated with 40% high magnesium slag and the set cement using ICT and XRD shows that the early strength of the set cement cured in 80 ℃ water bath is not high, but the long-term strength of the cement slurry is higher than that of the pure cement slurry. A microdilatant high magnesium slag cement slurry is formulated by adding 3% early strength additive and 1.5% fluid loss reducer. Experiment at 80 ℃ shows that the linear rates of expansion are 0.0062%(1 d), 0.045%(28 d) and 0.061%(90 d), respectively. The 1-day compressive strength of the set cement is 18.2 MPa, and has long-term strength that is greater than that of pure cement slurry. Porosities of the microdilatant high magnesium slag cement slurry and pure cement slurry(90 d) are 22.99% and 25.47%, respectively, with the former having less detrimental pores than that the later, compatible compressive strength test. The microdilatant high magnesium slag cement slurry has a comprehensive performance satisfying the needs of cementing job.