Simulation of axial tensile well deformation during reservoir compaction in offshore unconsolidated methane hydrate-bearing formation

Sand production encountered in the 2013 offshore field gas tests at Nankai Trough, Japan, could be attributed to well failure during reservoir compaction. In this study, integrity under various compaction patterns for Trough case is examined using a well-formation finite element model. The modelling details include inclusion of cement sheath as construction processes (such shrinkage). Well elongation overburden layer becomes significant when subsidence localized near wellbore large depressurization. Results show that maximum plastic deviatoric strain level reach 0.7% reaches 0.85 m and shrinkage limited. When rises 0.75%, increases 2.4% accumulates additional due its deformation being constrained by casing. order prevent from failure, it might effective hold pressure drawdown low (e.g., several MPa) until hydrate dissociation front advances certain radius couple tens metres).