Impact of multiscale modelling on predicted porosity and permeability distributions in the fluvial deposits of the Upper Lunde Member (Snorre Field, Norwegian Continental Shelf)

Abstract

Models of hydrocarbon reservoirs are often used to support management decisions about field development and redevelopment. Typical modelling workflows result in a reservoir and simulation model with a property distribution generally comparable to the well data, and this is often considered sufficient. The current study tests this assumption on the fluvial reservoir in the Upper Lunde Member of the Snorre Field where sedimentary heterogeneities at multiple scales influence reservoir properties such as porosity and permeability. This work shows that, by describing and modelling the sedimentary heterogeneities at several length scales in the reservoir, and by using a flow-based local upscaling method, the resulting porosity and permeability distribution at the scale of the reservoir and simulation model are significantly different from porosity and permeability distribution at the well data scale; the variance tends to reduce and, for permeability, the distribution type is changed from log-normal to normal. Reservoir property distributions based on multiscale modelling, sensitive to the representative elementary volumes for permeability, and upscaled in a realistic sedimentological framework, give a better representation of the effective permeability architecture.

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

“…At this stage, the majority of data are coming from the oil field rather from outcrop analogues, although it may be possible to incorporate data from nearby analogue fields. Outcrop analogues may, however, provide soft data on the breadth of the permeability range that is typically underestimated in the limited subsurface dataset, and also on the permeability structure that might exist to bridge the gap between core plug and cell in the model Keogh et al 2014;Nordahl et al 2014). …”

“…Multi-scale modelling is a specific kind of upscaling in which the elements that control fluid flow (laminae, bedforms, facies, facies associations) are specifically modelled at the representative elemental volume (REV) scale Ringrose et al 2008). This part of the workflow is not commonly used but is extremely valuable in reservoirs that are heterolithic at a wide range of scales (Keogh et al 2007(Keogh et al , 2014Nordahl et al 2014).…”

“…In complex heterolithic reservoirs there may be several scales of modelling, with the results from a fine-scale set of models being used to condition the inputs for the next level of model (Elfenbein et al 2005;Ringrose et al 2005). These small-scale models may be conditioned from process-based models (Nordahl et al 2014) or from studies of outcrops (Jackson et al 2003) or from a combination (Keogh et al 2014). …”

“…The papers cover a range of clastic depositional environments from fluvial (Alsop et al 2013;Pranter et al 2013;Rittersbacher et al 2013;Keogh et al 2014;Nordahl et al 2014) through paralic (Massey et al 2013;Rarity et al 2013) to deep marine (Eschard et al 2013). Two deal with LiDAR and virtual outcrop techniques from a ground base (Rarity et al 2013) and from a helicopter platform (Rittersbacher et al 2013); ground-based LiDAR was also used by Keogh et al (2014).…”

“…The data where then extrapolated in 3D and used to build flow simulation models that tested the importance of capturing some of the smaller, more complex bodies in fine grids. Nordahl et al (2014) and Keogh et al (2014) both illustrated the importance of detailed outcrop studies in pursuing the multi-scale modelling approach given that such a methodology requires information on the detailed architecture of sedimentary bodies at a variety of scales. Aas et al (2014) demonstrate the use of process-based modelling using computational fluid dynamics (CFD) to simulate the events that deposited turbidite beds in the Peira Cava deep-water system in SE France.…”