Improvement of mechanical properties of oil well cement-based composite materials using multiple flexible materials optimized based on response surface methodology

Abstract The cement sheath is easily brittle failure under the complex stress of oil and gas well. In order to improve the mechanical properties of oil well cement-based composite materials, the effects of carbon fiber, latex powder and powder rubber on oil well cement were studied, and the optimal ratio of three different flexible materials was selected using response surface methodology. The stress–strain and microstructure of oil well cement-based composite materials containing the optimal ratio of flexible materials were also analyzed. The results indicate that as the content of flexible materials increases, when the oil well cement only contains carbon fiber or latex powder, the compressive strength of the sample first increases and then decreases, and the elastic modulus continues to decrease. However, when only rubber powder is contained, the compressive strength and elastic modulus of the sample continue to decrease. The optimal ratio of three materials is 0.368 wt% of carbon fiber, 5.959 wt% of latex powder and 2.264 wt% of rubber powder. The oil well cement-based composite materials containing the optimal ratio of flexible materials has a good performances, with a compressive strength of 23.38 MPa and an elastic modulus of 6.034 GPa. The mechanical properties of oil well cement-based composite materials containing flexible materials were mainly improved through the synergistic effect of fiber, latex and rubber.