Surface-based reservoir modelling for flow simulation

Abstract

We present a surface-based approach to reservoir model construction in which all geological heterogeneity, whether structural, stratigraphic, sedimentological or diagenetic, that impacts on the spatial distribution of petrophysical properties is modelled as one or more discrete volumes bounded by surfaces. The modelled surfaces can be deterministically interpolated between control lines or points, or incorporate a stochastic element where control data are sparse. Models constructed from surfaces are not constrained by an underlying grid; indeed, the model is generated without reference to a grid. The only difference between ‘geological’ and ‘simulation’ models is that the latter incorporates a grid or mesh to allow numerical solution of the governing flow equations, the architecture of which is driven by the architecture of the modelled surfaces. This approach to gridding (or meshing) is directly compatible with the next generation of unstructured-mesh simulators, and allows the capabilities of the latter to be utilized fully in the modelling of complex reservoir architectures. A surface-based approach to model construction may facilitate a step change in reservoir modelling capabilities: once the requirement to upscale geological models to a structured simulation grid is removed, there is no need to build geological models that are restricted by grid resolution.

Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 1. Concepts and application

“…Although these studies have demonstrated that, under certain displacement conditions, it is important to include clinoforms in models of shallow-marine reservoirs, it is not clear how these models could be applied in the subsurface or at the full-field scale. Other studies have indicated that surfaces should be used to incorporate clinoforms into reservoir models, as surfaces are much less computationally expensive to generate and manipulate than large 3-D geocellular grids Sech et al, 2009;Jackson et al, 2014). These deterministic approaches are appropriate for modeling clinoforms that are tightly constrained by outcrop data but do not allow flexibility in conditioning clinoform geometry and distribution to sparser data sets with a large degree of uncertainty.…”

The application of outcrop analogues in geological modelling: a review, present status and future outlook

“…At present, virtually all reservoir modelling systems are based on cellular grids that are populated with properties (Denver & Phillips 1990). Gridded models are associated with problems and, while in the future we may be less dependent on such an approach (Jackson et al 2013), at present gridded models are industry standard. Grid design includes layer strategy and grid resolution (including grid cell dimensions and variability), as well as grid cell geometry.…”

“…Grid design includes layer strategy and grid resolution (including grid cell dimensions and variability), as well as grid cell geometry. The grid design can significantly impact the behaviour of the model (Jackson & Muggeridge 2000;Yoon et al 2001;Jackson et al 2013). Grid design is a key part of the conceptual model, and should reflect the knowledge on the scale and geometry of heterogeneities, in relation to fluid types present, which will impact flow.…”

“…Finally, Jackson et al (2013) provide a view into the future of simulation. These authors demonstrate an alternative method for building static geological models heavily driven by geological surfaces that provide a framework for, and even define, the geobodies that are being modelled.…”

Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 2. Impact on fluid flow and hydrocarbon recovery in fluvial-dominated deltaic reservoirs

“…A surface-based approach to model construction Jackson et al, 2014) was followed, in which surfaces are used to represent both key stratigraphic surfaces and facies boundaries. Surfaces are modeled before the grid is defined, so model geometry is not limited by grid resolution ).…”