Mechanical behavior of casing crossing slip formation in waterflooding oilfields

The failure rate of casings in waterflooding oilfields is high. Casing failure reduces the longevity of wells and economic benefit of oilfields. Based on logging interpretation and statistical analysis, formation slippage is identified to be the dominated cause of casing failure. A finite element model (FEM) of well crossing slip formation is established and validated by the experimental data. By adopting the FEM, nonlinear mechanical behavior of casing crossing slip formation is analyzed. Results indicate that there is an approximate sinusoidal relationship between the deflection of casing and the distance from slip plane. The peak deflections of casing are slightly smaller than the displacements of slip formations due to its high flexural rigidity. Stress concentration occurs at the places those are ±0.5 m from the slip plane. The places of the peak Mises stress are closer than those of the peak deflection. The predicted casing radii and integrity status are consistent with the logging data. The findings can provide a reference for casing design in waterflooding oilfields.