稠油热采条件下矿渣对磷铝酸盐水泥石耐高温性影响研究

High Temperature Resistance of Aluminophosphate Cement with Slag for Thermal Recovery Wells

针对硅酸盐水泥石经热力采油后耐高温性能急剧衰退的问题。采用具备更好耐高温特性的磷铝酸盐水泥,但是磷铝酸盐水泥高温后的抗压强度仍存在一定的衰退的问题,实验通过在磷铝酸盐水泥中掺入矿渣改善磷铝酸盐水泥石耐高温特性并采用XRD及SEM测试手段分析机理。结果表明:加入矿渣不仅有利于水泥石低温强度的发展,而且能够明显改善磷铝酸盐水泥石的耐高温特性;矿渣加入后C2ASH8的形成有利于水泥石低温下的强度发展,C3AS2H2的形成有利于水泥石高温后的强度发展,同时,为提高水泥石的耐高温特性应尽量避免高温后C3ASH4的生成。加入矿渣后的水泥石经高温养护后晶体结构发育良好,排列致密,从而使得水泥石具有良好的抗高温性能,进而有利于改善水泥环的完整性。

The crucial problem of cement in heavy oil thermal recovery is sharp strength recession in high temperature. Aluminophosphate cement has a better high temperature resistance in comparison with ordinary silicate cement, but its compressive strength recession in high temperature still appears. The results show that after adding slag into aluminophosphate cement can not only develop compressive strength of aluminophosphate cement in low temperature, but it can also improve the high temperature resistance of it. The formation of C2ASHs help with the development of cement strength at low temperatures, and the formation of C3AS2H2 is in the benefit of high temperature resistance. Meanwhile, in order to increase the temperature resistance of aluminophosphate cement, C3ASH4 phase should be avoided. Crystal structure of cement after high temperature, which is well developed with compact arrangement, allows cement to maintain high temperature resistance. At last, the integrity of cement sheath can be improved.