Fly ash is most commonly used as a partial replacement of Portland cement in lightweight oil-well cement systems. The fly ash is a waste material generated during coal combustion to generate energy. The material is facing an imminent phase-out due to global warming issues associated with coal combustion. This study, for the first time, investigates the potential of calcined calcium bentonite as an alternative pozzolanic material in oil-well cementing.

The bentonite was calcined at 830 °C for 3 h. Lightweight cement slurries were formulated at 12.5 ppg using the calcined clay in the ratio of 10%–30% cement replacement and cured at a BHST of 50 °C and a BHP of 1000 psi. The optimum concentration was found to be 20%.

A comparative study of the calcined calcium bentonite (CCB) and fly ash-based systems designed at 20% cement replacement was performed. The XRD and thermogravimetry analysis showed that CCB and fly ash exhibit similar pozzolanic reactivity and the cement systems designed with these materials show equivalent characteristics in terms of rheology, strength, pore size distribution, porosity, and microstructural properties. The addition of 5%–10% silica fume can be used to further improve the early-age compressive strength of low-density cement systems designed with calcined calcium bentonite.

在轻质油井水泥系统中，粉煤灰最常被用作波特兰水泥的部分替代品。粉煤灰是煤燃烧过程中产生的废料，用于产生能量。由于与燃煤有关的全球变暖问题，该材料即将面临淘汰。这项研究首次研究了煅烧钙膨润土作为油井固井水泥中火山灰替代材料的潜力。

膨润土在830°C下煅烧3 h。使用煅烧粘土以水泥替代量的10％–30％的比例配制轻质水泥浆，含量为12.5 ppg，并在50°C的BHST和1000 psi的BHP下固化。发现最佳浓度为20％。

进行了煅烧钙膨润土（CCB）和粉煤灰基体系（水泥替代量为20％）的比较研究。XRD和热重分析表明，CCB和粉煤灰表现出相似的火山灰反应性，用这些材料设计的水泥体系在流变性，强度，孔径分布，孔隙率和微观结构特性方面表现出相同的特性。添加5％–10％的硅粉可进一步改善采用煅烧钙膨润土设计的低密度水泥体系的早期抗压强度。