复合膨胀剂对掺矿渣油井水泥性能的影响

针对普通油井水泥固井存在水泥浆高失水和水泥凝固过程中的体积收缩等问题，研究了G级油井水泥-矿渣-复合膨胀剂三元复合胶凝材料的膨胀与强度的协调性。通过汞压入法（MIP）和扫描电镜（SEM）等现代测试方法对矿渣油井水泥的水化硬化特性和机理进行了研究。试验结果表明，矿渣对改善G级油井水泥膨胀性能和力学性能有利；掺入煅烧MgO，在80 ℃水浴养护下，可得到比较理想的自生体积膨胀变形率，用限制膨胀来补偿水泥的限制收缩；掺钙镁复合膨胀剂，能改善矿渣油井水泥的微观结构，使得结构致密，抗压强度相应增加，可制备高性能膨胀油井水泥。

INFLUENCE OF COMPLEX MAGNESIA EXPANSIVE AGENT ON PROPERTIES OF SLAG CEMENT

Because slurry made of common cement has problems like high water loss, and volumetric shrinkage during hardening, the balance between the expansion and the strength of compound gelling material of G grade oil well cement, slag, complex expansive agent was investigated. By modern test methods like mercury intrusion pore measurement (MIP) and scanning electron microscope (SEM), the hydration and hardening mechanism of the slag cement was analyzed. The results show the slag is useful to improve the expansion and mechanical properties of the G grade cement. And by adding a magnesia expensive agent, through water bath curing at 80℃, ideal spontaneous volume expansion ratio can be gained; the shrinkage can be made up by limiting expansion. And through analysis of microstructure, it is found the addition of calcium magnesium compound expansive agent can improve the microscopic pore structure of cement stone, making the cement stone more compact, its compressive strength improved, and thus high performance expensive oil cement can be prepared.