Numerical modeling of multilateral junction stability in the Montney shale play

While drilling and completing multilateral wells in unconventional shale plays, a major concern is the stability of the junction. If the junction area is to remain open while producing, the stability of the junction is essential until the end of the well life. Due to the complex geometry of the junction, numerical simulations are typically required to understand the stress concentrations and simulate the stability of the junction. A dual-lateral well was to be drilled and completed in the Montney shale play in Alberta, with the two laterals targeting Middle and Lower Montney, respectively. With the Technical Advancement of Multilaterals (TAML) Level 2 multilateral completion, one lateral would be cased and the other would remain open. Because relatively large drawdown pressures were planned for the well, understanding of the junction stability became an important consideration not only while drilling the lateral, but also while the well was producing. This paper will present a geomechanical analysis of the multilateral junction stability under two drawdown-pressure conditions, including determination of the mechanical properties and in-situ stresses, numerical simulation of the stress concentrations, and rock deformations at the junction.