Calcium Phosphate Cement Slurries for Thermal Production Wells

摘要

Calcium phosphate cement slurries used for thermal production wells cementing adapt to the soft formations and steam huff and puff were investigated. Calcium phosphate cement slurries were developed with density of 1.50 g/cm~3 and 1.90 g/cm~3, respectively. The properties of cement slurries and set cements were also studied. The results indicate that calcium phosphate cement slurries can meet the requirements for thermal recovery wells cementing. The long-term compressive strength of the set cement at 300°C was not retrogressive and compressive strength after curing for 28d at 300°C was more than 16 MPa and 24 MPa for cement with density of 1.50 g/cm~3 and 1.90 g/cm~3, respectively. The conclusion of X- ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) of calcium phosphate cement samples indicate that the crystalline phases leading to high-temperature strength retrogression did not exist.