Prediction of the Optimal Drilling Mud Weight Based on the Normalized Yielded Zone Area (NYZA) in One of the Iranian Oil Fields

Abstract

Hole problems experienced during the drilling phase of operations are often the consequence of mechanical wellbore instability. This leads to higher than necessary drilling costs. The only controllable factor that can prevent wellbore instability is the drilling mud. In this study, the optimal drilling mud weight to prevent instability using the Finite Element Method (FEM) was simulated in one of the fields of Southwest Iran. To determine the optimal drilling mud weight, the various hydrostatic pressure equivalents to mud weight were applied and plastic strains and stresses were obtained and analyzed. The obtained results from the predicted mud weight using FEM appeared to have a 0.14 % error with the reported drilling mud weight, which shows a good agreement between the obtained simulated results and field evaluations. doi:10.14456/WJST.2014.43

Keywords

• Stability
• optimum mud weight
• finite element
• plastic strain
• Drucker-Prager criterion