Correlation of Numerical Simulation and DIC Strain Measurements for a Multilateral Junction while Subjected to High Internal Pressure

Abstract

Abstract This paper investigates stress and strain distributions determined through finite-element analysis (FEA) simulation and three-dimensional (3-D), digital image correlation (DIC) measurements obtained during full-scale testing of a Technology Advancement of Multilaterals (TAML) Level 5 multilateral junction prototype subjected to high internal pressure. A multilateral well consists of one main wellbore with one or more lateral wellbores drilled from the main wellbore. The point at which a lateral is drilled from the main wellbore is identified as the wellbore junction. The wellbore junction's integrity is important to the success of the multilateral well construction (Samuel and Gao 2007). A TAML Level 5 junction is necessary to create pressure isolation across both lateral and mainbore legs to withstand high-pressure/high-temperature (HPHT) conditions in deeper oil and gas wells (TAML 2002). This study discusses a completion system TAML Level 5 multilateral junction subjected to a qualification program, including internal and external pressure cycles with the junction in a deployed position to verify pressure integrity. The junction was evaluated through both numerical simulation and full-scale physical testing of a prototype, which was designed to be run in 10-3/4-in., 65.7-lb casing with a 5-1/2-in. lateral leg and a 3-1/2-in. mainbore leg. This paper investigates stress and strain distributions determined through FEA simulation and 3-D DIC measurements obtained during full-scale testing of a junction at 6,000-psi internal pressure. Although DIC has been widely used for strain measurements within the industry, it was introduced into the junction-test program to meet increasingly challenging environments. Compared to conventional strain-gauge measurements, DIC allows for full-field strain measurements, including points at which complex geometries exist, such as the external intersection of the main and lateral legs, which is commonly the critical area with high stress concentrations. A correlation and comparison between the numerical simulation and DIC measurements are discussed to qualitatively validate the FEA model with experimental results. The petroleum industry requires more advanced technologies as wells are drilled in more challenging environments (i.e., deep sea, artic environments, higher pressures, etc.). To provide these advanced technologies, engineers need the capability to help ensure their designs meet the requirements of such challenging environments. DIC provides a means to qualitatively validate the numerical simulations for complex designs.