废弃玻璃粉对水泥石高温抗压强度和微观结构的影响

废弃玻璃粉作为一种高SiO₂含量的固体废弃物,可以有效防止油井水泥石在高温下的强度衰退,从而提升深井、超深井固井水泥环长期封隔完整性。本文研究了150 ℃、21 MPa下,不同粒径废弃玻璃粉对水泥石抗压强度、渗透率和微观结构的影响。结果表明:150 ℃、21 MPa下净浆水泥石180 d抗压强度为8.57 MPa,较1 d衰退76.04%;掺入废弃玻璃粉可以提高水泥石抗压强度的长期稳定性,在内掺40%(质量分数)粒径为45 μm的废弃玻璃粉情况下,水泥石在180 d时抗压强度为31.85 MPa,较1 d仅衰退3.95%,渗透率为1.28×10^-2 mD,较1 d降低16.88%;掺入废弃玻璃粉改变了水泥石150 ℃、21 MPa下的物相组成,净浆水泥石的主要结晶相为氢氧化钙和水硅钙石,掺入不同粒径废弃玻璃粉的水泥石主要结晶相为硬硅钙石和托贝莫来石;内掺40%粒径为45 μm的废弃玻璃粉的水泥石中托贝莫来石晶粒尺寸稳定;随龄期增加,净浆水泥石孔结构向大孔径发展,内掺40%粒径为45 μm的废弃玻璃粉的水泥石的孔结构更加致密,180 d内各龄期均以凝胶孔为主。

Effect of Waste Glass Powder on High Temperature Compressive Strength and Microstructure of Cement Stone

Waste glass powder, as a kind of solid waste with high content of SiO₂, can effectively prevent the strength retrogression of oil well cement stone at high temperature, thereby improving the long-term sealing integrity of cement sheath in deep and ultra-deep wells. The effect of waste glass powder on compressive strength and microstructure of cement stone at 150 ℃, 21 MPa was studied in this paper. The results show that the 180 d compressive strength of neat cement stone is 8.57 MPa, which is 76.04% lower than 1 d compressive strength. The incorporation of waste glass powder improves the long-term stability of cement stone compressive strength. When 40% (mass fraction) cement is replaced by waste glass powder with a particle size of 45 μm, the 180 d compressive strength of cement stone is 31.85 MPa, which is only 3.95% lower than 1 d compressive strength. In addition, the 180 d permeability of cement stone is 1.28×10^-2 mD, which is 16.88% lower than 1 d permeability. The incorporation of waste glass powder changes the phase composition of cement stone. The neat cement stone is composed of portlandite and hillebrandite. The cement stone incorporating 40% waste glass powder with a particle size of 45 μm is made up of xonotlite and tobermorite. The grain size of xonotlite and tobermorite in cement stone is stable after incorporating 40% waste glass powder with a particle size of 45 μm. More large pores are produced in neat cement stone with the increase of curing age, while the structure in cement stone incorporating 40% waste glass powder with a particle size of 45 μm is denser, and gel pores are dominated within 180 d.