一种新型低放热水泥材料的室内性能研究

海洋深水钻探常常钻遇浅层水合物层，常规低温水泥浆放热量大，固井期间会引起水合物层不稳定，影响固井质量。通过对几种胶凝材料的筛选研究，开发了一种新型低放热水泥材料，从而建立了一套可适于深水浅层水合物层固井的低热水泥浆体系。该水泥浆体系在密度为1.40～1.60 g/cm3时，3 d的水化热均小于200 J/g，水泥石在10℃下养护24 h后的抗压强度大于3.5 MPa，降失水性能较常规低热水泥有较大提高，均小于50 mL，流变性测试φ₃₀₀均在300以下，同时新型低热水泥性能比普通低热水泥水化热更低，稠化时间可调，室内实验表明，新型低热水泥浆体系在低温环境下具有低水化热、高早强、低失水以及稠化性良好等特点，能够满足海洋深水水合物层固井作业的要求。 

Laboratory Study on a New Low Heat Cement

Shallow hydrate zones are often encountered in offshore deep drilling. Conventional low temperature cement releases quite large amount of heat which, during well cementing, will negatively affect the quality of well cementing because the heat released causes the hydrate zones to destabilize. A special low heat aluminophosphate cement has been prepared in laboratory, and is compounded with high belite sulphoaluminate cement and slug cement to form a new low heat cement-the APE cement. A low heat cement slurry suitable for cementing deep water wells with shallow hydrate zones is prepared by mixing the APE cement and cement additives of independent intellectual property, such as low temperature filter loss reducer, early strength agent and dispersant. The heat of hydration of this cement slurry at density between 1.40 g/cm3 and 1.60 g/cm3 is less than 200 J/g. Set cement aged at 10℃ for 24 h has compressive strength of 3.5 MPa. Filtration control of the cement slurry is less than 50 mL, better than that of the conventional cement slurries. φ300 reading of the cement slurry is less than 300. The new cement slurry has 3 d heat of hydration that is 58 J/g less than that of the conventional low heat cement slurries, and thickening time that is adjustable. Laboratory experiment shows that the new low heat cement slurry has, at low temperatures, low heat of hydration, high early strength, low filtration rate and good thickening property, and is able to satisfy the requirements for cementing deep water wells penetrating hydrate zones.