Shiyuan Li

Numerical modelling of the displacement and deformation of embedded rock bodies during salt tectonics: A case study from the South Oman Salt Basin

Abstract Large rock inclusions are embedded in many salt bodies and these respond to the movements of the salt in a variety of ways including displacement, folding and fracturing. One mode of salt tectonics is downbuilding, whereby the top of a developing diapir remains in the same vertical position while the surrounding overburden sediments subside. We investigate how the differential displacement of the top salt surface caused by downbuilding induces ductile salt flow and the associated deformation of brittle stringers by an iterative procedure to detect and simulate conditions for the onset of localization of deformation in a finite element model, in combination with adaptive remeshing. The model set-up is constrained by observations from the South Oman Salt Basin, where large carbonate bodies encased in salt form substantial hydrocarbon plays. The model shows that, depending on the displacement of the top salt, the stringers can break very soon after the onset of salt tectonics and can deform in different ways. If extension along the inclusion dominates, stringers are broken by tensile fractures and boudinage at relatively shallow depth. Spacing of the boudin–bounding faults can be as close as 3–4 times the thickness of the stringer. In contrast, salt shortening along the inclusion may lead to folding or thrusting of stringers.

Modeling of stringer deformation and displacement in Ara salt after the end of salt tectonics

Abstract The present work considers numerical models of large rock inclusions (stringers) are embedded in many salt bodies. The study has been made to investigate the influence of salt tectonic process, such as downbuilding, on the deformation and displacement of stringers. In this research, the focus has been on establishing numerical models of the deformation and displacement of stringer embedded in salt (at rest) after occurrences of salt tectonics. The problem of influence of eventual tectonic processes at larger stage is addressed on the development of stringers. The numerical model is based on finite element method in combination with adaptive remeshing. The results show that the stringers experience minor sinking and the differential stress in salt and the differential stress in the stringer decrease during the period after salt tectonics. The change of stress of reservoir will influence drilling process and oil or gas production.

A sensitivity study on the numerical model of displacement and deformation of embedded brittle rock bodies in extension environment during salt tectonics

Many salt bodies contain large rock inclusions (called stringers) such as carbonate or anhydrite bodies. Mostly, large rock inclusions embedded in salt bodies have different ways of movement and deformation, including displacement, folding and fracturing. A finite element model with adaptive remeshing has been built for downbuilding simulation. The standard model set-up is constrained by observations from the South Oman Salt Basin. Based on the generic model in the previous research which shows the fracture, overtrusting or folding deformation during downbuilding process, a sensitivity study has been conducted on the numerical model of the deformation and displacement of brittle rock bodies, including the parameters such as the initial depth and the distance between them. The results of simulation are analyzed based on the data from SOSB and Zechstein salt basin. The study shows that the frequency of the break and the size of stringer fragments are strongly affected by the initial depth and thickness of stringers and the basement configuration.