Engineered methodology for design verification and validation of ultra-deep high pressure high temperature oil and gas well control equipment

An apparatus designed for use in oil and gas wells in a high pressure high temperature environment, including for drilling, completion and production operations, the apparatus including components analyzed using a computer system including a processor, memory, input/output devices, and software, the software including instructions for execution of the computer system, having the characteristics comprising:

• (a) when analyzed using the computer system for global static strength and local plasticity using an elastic-plastic finite element model with respect to certain preset load conditions and using the least favorable combination of dimensional tolerances for each component and based on an initial mesh density, the components:
• (i) achieve a stable model convergence using all preset load conditions;
• (ii) exhibit a mesh density where further refinement in mesh density of stressed portions of the components will result in less than a pre-selected mesh refinement percentage change in plastic strain;
• (iii) achieve a strain limit damage for the stressed portions of the components identified by the model that is less than a set strain limit damage amount;
• (b) when subjected to a ratcheting assessment by elastic-perfectly plastic analysis using the computer system, components that exhibit local plasticity at the maximum combination of preset load conditions are resistant to ratcheting using the preset load conditions by demonstrating at least one ratcheting criterion;
• and
• (c) achieve acceptance criteria when the fatigue sensitive locations of the components are subjected to a fatigue analysis using the computer system.

A computer system for the design verification and validation of surface and sub-surface oil and gas equipment components including a processor, memory, input/output devices, and software, the software including instructions for execution of the computer system, the instructions comprising:

• (a) analyzing the components for global static strength and local plasticity with an elastic-plastic finite element model, the analysis using preset load conditions and the least favorable combination of dimensional tolerances for each component based on an initial mesh density and comprising the steps of:
• (i) confirming that the design of the component results in a stable model convergence using all preset load conditions;
• (ii) conducting a mesh refinement study on stressed portions of the components, where further refinement in mesh density will result in less than a pre-selected mesh refinement percentage change in plastic strain;
• (iii) confirming that stressed portions of the components identified by the model have strain limit damage that is less than a set strain limit damage amount;
• (b) conducting a ratcheting assessment by running an elastic-perfectly plastic analysis with the model on all equipment components that exhibit local plasticity at a maximum combination of preset load conditions to determine resistance to ratcheting by applying the maximum preset load conditions to such components to demonstrate at least one ratcheting criterion;
• and
• (c) examining all components to determine fatigue sensitive locations and subjecting components exhibiting fatigue sensitive locations to a fatigue analysis.