3D finite element modelling of multilateral junction wellbore stability

Abstract

Wellbore failure can occur at different stages of operations. For example, wellbore collapse might happen during drilling and/or during production. The drilling process results in the removal of an already stressed rock material. If the induced stresses near the wellbore exceed the strength of rock, wellbore failure occurs. The production process also changes the effective stresses around the wellbore. Such changes in stresses can be significant for high drawdown pressures and can trigger wellbore failure. In this paper, the Mohr-Coulomb failure criterion with a hyperbolic hardening is used. The model parameters are identified from triaxial compression tests. The numerical simulations of laboratory tests showed that the model can reproduce the mechanical behaviour of sandstone. In addition, the simulations of multilateral junction stability experiments showed that the model was able to reproduce yielding and failure at the multilateral junction for different levels of applied stresses. Finally, a numerical example examining multilateral junction stability in an open borehole during drilling and production is presented. The results illustrate the development of a localized failure zone proximate to the area where two wellbore tracks join, particularly on the side with a sharp approaching angle, which would significantly increase the risk of wellbore collapse at the junction.

Study on Wellbore Stability of Multilateral Wells under Seepage-Stress Coupling Condition Based on Finite Element Simulation

“…The results showed that, as the dip increases, the laterals become more stable and the direction of the maximum principal stress become the optimal direction for all the stress states considered. Mohamad [20] used the hyperbolic hardening Mohr-Coulomb failure criterion to study the borehole stability of open hole multilateral Wells. The results showed that failure areas would appear at the intersection of main borehole and branch borehole, especially the collapse risk near the sharp corner of the wall would increase significantly.…”

An evaluation of viscous deformation of chalk on wellbore stability

“…It is therefore an important issue in geothermal, gas and oil industry as a response to the increasing of exploration in complex areas during drilling and production especially where horizontal and extended reach wells are drilled with completely open hole lateral sections. This concern becomes more critical in recent drilling innovations such as high pressure jet drilling, underbalanced drilling techniques, re-entry horizontal wells and multiple laterals from a single vertical or horizontal well (Medetbekova et al, 2021(Medetbekova et al, , 2020aMohamad-Hussein and Heiland, 2018;Parra et al, 2003). Wellbore instabilities take several forms (Paić et al, 2007).…”

Evaluation of the Stress State Around Boreholes Using Well Log Data: A Case Study in the Sergipe-Alagoas Basin, Brazil

“…Injection and/or fluid production in a reservoir modifies saturation and pressure within the porous media and changes the effective stresses around the wellbore (Hussein & Heiland, 2018). This affects the stress states of rocks, which may result in, among other factors, pore collapse, rock fracture, sand production, surface subsidence, reactivation of geological faults, exudation, and, in more critical situations, blowouts.…”