稠油热采井抗350℃高温硅酸盐基水泥浆

针对蒸汽驱稠油热采井井筒温度高达350℃，常规加砂水泥在高温下结构疏松，抗压强度低，铝酸盐及磷铝酸盐水泥成本高及与硅酸盐水泥污染严重等问题。通过探索高温增强作用机理，开发出高温特种增强材料，结合配套硅酸盐外加剂，研发出综合性能良好的抗350℃高温硅酸盐基水泥浆，并进行了水泥浆综合性能测试、XRD晶相组分分析、SEM晶相形貌分析，结果表明，抗350℃高温硅酸盐基水泥浆的沉降稳定性小于0.02 g/cm3，游离液量为0，API失水量小于50 mL，流动度大于20 cm，70℃水泥石24 h抗压强度大于14 MPa，且3轮次下350℃高温水泥石强度大于40 MPa，长期强度发展稳定，满足稠油热采井的工程应用需求，突破了超高温下硅酸盐水泥强度低、铝酸盐及磷铝酸盐水泥必用的困境，促进了超高温水泥浆技术进步。 

A 350 ℃ High Temperature Silicate Cement Slurry Used in Cementing Heavy Oil Thermal Production Wells

Conventional cement slurries with sand have loose structures and low compressive capacity at high temperatures such as 350℃ in heavy oil thermal production wells. Aluminate cement and phosphoaluminate cement are expensive, while silicate cement always cause contamination to the reservoir formations. Based on the understanding of high temperature strengthening mechanism, some special strengthening additives were developed. These additives, plus some silicate additives, were used to formulate a cement slurry that is resistant to 350℃ high temperature to deal with the problems as said above. The general performance of the cement slurry was tested, the composition of the crystal phase of the cement was analyzed with XRD, and the morphology of the crystal phase was analyzed with SEM. It was found that the high temperature (HT) silicate cement slurry had top and bottom density difference of less than 0.02 g/cm3, zero free water, API filtration rate of less than 50 mL, and mobility of greater than 20 cm. The 24 h compressive strength of the set cement of the HT silicate cement slurry at 70℃ was greater than 14 MPa, and the compressive strength of the set cement in three rounds of test was greater than 40 MPa, indicating that the HT cement slurry has stable long-term strength development, and therefore satisfies the requirement of heavy oil thermal production. Silicate cement slurry used in previous ultra-high temperature operations had low strength, to have high strength, expensive aluminate cement or phosphoaluminate cement had to be used. With the development of the high temperature silicate cement, all these difficulties have diminished, and progress in ultra-high cement slurry technology has been made.