Well Integrity Mapping Using Hybrid Model Based on Physics of Failure and Data-Driven Methods

Presence of H2S in high pressure and high temperature wells with pressures greater than 15,000 psi or temperatures of 350 °F can lead to strength reduction of casing strings and advance the time to failure. Casing strings also get damaged during drilling. The objective of this study is to develop a hybrid model based on Physics of failure and data driven algorithms that can estimate remaining useful life of production casing in high pressure, high temperature, and sour well conditions. A unique degradation modeling and prognostics framework and analysis are presented in this study. A simulation tool is built for the analysis. The production casing grades P-110, Q-125 and V-150 undergo reduction in strength due to wear during drilling, stress and hydrogen induced cracking over a period of ten years. The failure probability of reduced strength of casing changes with time. The remaining useful life is calculated for the depths of interest and time along with 95% confidence intervals. The model can be expanded later to include actual tests or monitored well data.