Deformation, stress, and pore pressure in an evolving suprasalt basin

Abstract

We develop a two‐dimensional plane strain large‐deformation coupled poroelastoplastic finite element model to simulate initiation and rise of a salt wall from a flat salt body during sedimentation. We run transient analyses with high‐permeability and low‐permeability sediments in the model to simulate drained conditions and overpressure (or pore fluid overpressure). We investigate deformation, stress, and overpressure in the evolving suprasalt basin. Model results show that horizontal stress increases even higher than vertical stress at the flank of the salt wall and in the minibasin due to horizontal pushing out of the rising salt wall and that orientations of principal stresses rotate in the minibasin relative to far‐field stress state. Model predicts that compared with far‐field overpressure, the overpressure near the salt wall and within the minibasin is largely perturbed by the salt body. We find that perturbations of pore pressure (or pore fluid pressure) near the salt wall and within the minibasin cannot be resolved by traditional pore pressure prediction methods such as normal compaction trend approach and mean stress model approach. In order to predict pore pressure more accurately, especially in the regions near salt bodies or where stresses are perturbed, we need to apply a method that includes both effects of mean effective stress and deviatoric stress on pore pressure and compaction, for example, the Modified Cam Clay model approach, to pore pressure prediction. Our results provide geoscientists insights into evolution of salt basins, near‐salt deformation, stress, overpressure, and overpressure prediction methods and have implications for near‐salt wellbore drilling programs.

A blended transient/quasistatic Lagrangian framework for salt tectonics simulations with stabilized tetrahedral finite elements

“…Hence, the development of improved forward models that directly predict salt diapir shapes under various conditions becomes very valuable for structural geologists. In addition, whenever drilling in and around salt is performed, quantifying the stress field inside and especially around salt domes (in terms of the magnitudes and directions of principal stresses) is of great interest, because of its effects on well‐bore stability and borehole collapse 7‐10 …”

Overpressure evolution controlled by spatial and temporal changes in the sedimentation rate: Insights from a basin modelling study in offshore Suriname

“…The modelling approach, including geomechanical pore‐elastic modelling, has been increasingly applied to reconstruct pore pressure evolution in various sedimentary basins (e.g. Barabasch et al., 2019; Borge, 2002; Burgreen‐Chan et al., 2016; Luo et al., 2017; Mosca et al., 2018; Neumaier et al., 2014; Obradors‐Prats et al., 2017, 2019). Based on the results of the well data analysis and basin modelling, we examined the overpressure history in the study area from the viewpoints of the spatio‐temporal changes in sedimentation rate and the hinterland evolution.…”

Fault and fracture patterns around a strike-slip influenced salt wall

“…Although analysis of seismic sections may permit imaging of larger scale faulting around salt diapirs, the distribution and timing of many fractures can be difficult to ascertain due to steeply dipping beds around the flanks of the diapir, together with potential fluid movements adjacent to the salt (e.g. Davison et al, 2000a, b;Vandeginste et al, 2017;Luo et al, 2017). While drill cores and well logs may provide some help in estimating fracture intensity within the overburden (e.g.…”