Structural Reliability: Assessing the Condition and Reliability of Casing in Compacting Reservoirs

Casing has a higher likelihood of failure in compacting reservoir than in a typical reservoir. Casing fails because reservoir<br>compaction induces compression and shear stresses onto it. The compaction occurs as reservoir pressure depletes during<br>production. High compacted reservoirs typically are composed of unconsolidated, overpressured rocks such as chalk,<br>diatomite, and sandstone. Pore pressure depletion increases effective stress, which is the rock matrix stress pushing upward<br>against overburden pressure. Effective stress may exceed rock compressive strength, inducing compaction. Wells in<br>compacting reservoirs are likely to fail and to have high deformation rates.