This paper presents the construction of a high-quality, robust hybrid grid for near-wellbore modeling in the vicinity of a deviated well. The far-field region is modeled using a corner-point grid, while the near-wellbore region-referred to as the volume of interest-is remeshed using a layered unstructured grid, which consists of a combination of Voronoi and radial sub-grids. A detailed gridding and simulation workflow is outlined. The construction of the novel layered unstructured grid begins with building a base surface grid on the surface typically aligned to middle well point. The grids on the other surfaces are built through preserving the base topology but adjusting the nodes of base grid to fit the well points deviating from the base well point. A flow-based node rearrangement method is proposed to adjust the grid nodes to gain high-quality grids on each surface. The positions of new nodes are determined by ensuring equal streamlines and pressure values between nodes on the base and target surfaces, improving grid orthogonality as streamlines remain perpendicular to equipotential lines. The method’s ability to generate high-quality grids for deviated wells is demonstrated through illustrative and validation examples. Computational performance is assessed through direct comparisons across three case studies, showing that the new near-wellbore modeling model provides accurate well solutions and pressure maps with a reasonable computational cost. Additionally, the near-wellbore modeling model outperforms standard models in capturing gas flow with high compressibility, describing flow behavior in heterogeneous reservoirs, and predicting production parameters in multilayer systems.

Physics-based computational modeling of subsurface CO₂ migration constitutes the primary tool to assess geologic carbon storage. Such models are often required to plan injection operations and assess hazards such as CO₂ migration into units above the storage formation. Here, we present three tools developed to increase fidelity of black-oil type geologic carbon storage models in the open-source MATLAB Reservoir Simulation Toolbox. These tools, which are published in the $\mathtt{\text{co2lab-mit}}$ module, include functionality to: (1) Calculate and output PVT properties of miscible brine and CO₂ as a function of pressure, temperature, and salinity; (2) account for relative permeability hysteresis, necessary to model residual trapping; and (3) model CO₂ transport due to concentration gradients (molecular diffusion). We validate our implementation with published results including experimental observations, present $\mathtt{\text{MRST}}$ examples, and conclude with some remarks on applicability, limitations, and potential extensions. Source code and examples are provided.

Several graphical methods have been developed to understand the stratigraphy observed in wells and assist experts in estimating rock quality, defining limits for barriers, baffles, and speed zones, and in particular, delineating hydraulic flow units. At present, there exists no computational tool that bundles the main graphical methods used for defining flow units. This paper introduces an add-on module to the MATLAB Reservoir Simulation Toolbox that contains computational routines to carry out such graphical analyses, both qualitatively and quantitatively. We also describe a new secondary method defined as the derivative of the stratigraphic modified Lorenz plot, which we use to classify depth ranges within the reservoir into barriers, strong baffles, weak baffles, and normal units, based on flow unit speed over those depths. We demonstrate the capabilities of the "Graphical Analysis for Well Placement Strategy" module by applying it to several case studies of both real and synthetic reservoirs.