A screening assessment of the impact of sedimentological heterogeneity on CO ₂ migration and stratigraphic-baffling potential: Sherwood and Bunter sandstones, UK

Abstract

We use a combination of experimental design, sketch-based reservoir modelling and flow diagnostics to rapidly screen the impact of sedimentological heterogeneities that constitute baffles and barriers on CO 2 migration in depleted hydrocarbon reservoirs and saline aquifers of the Sherwood Sandstone Group and Bunter Sandstone Formation, UK. These storage units consist of fluvial sandstones with subordinate aeolian sandstones, floodplain and sabkha heteroliths and lacustrine mudstones. The predominant control on effective horizontal permeability is the lateral continuity of aeolian-sandstone intervals. Effective vertical permeability is controlled by the lateral extent, thickness and abundance of lacustrine-mudstone layers and aeolian-sandstone layers, and the mean lateral extent and mean vertical spacing of carbonate-cemented basal channel lags in fluvial facies-association layers. The baffling effect on CO 2 migration and retention is approximated by the pore volume injected at breakthrough time, which is controlled largely by three heterogeneities, in order of decreasing impact: (1) the lateral continuity of aeolian-sandstone intervals; (2) the lateral extent of lacustrine-mudstone layers; and (3) the thickness and abundance of fluvial-sandstone, aeolian-sandstone, floodplain-and-sabkha-heterolith and lacustrine-mudstone layers. Future effort should be focused on characterizing these three heterogeneities as a precursor for later capillary, dissolution and mineral trapping.

Enabling secure subsurface storage in future energy systems: an introduction

“…One key factor that controls fluid flow behaviour in the reservoir is the heterogeneity of the reservoir with respect to permeability and porosity. Alshakri et al (2023) highlight the role of sedimentological heterogeneities within the Triassic Sherwood Sandstone Group and Bunter Sandstone Formation in the UK as baffles and barriers for CO 2 migration. The authors rapidly screen the impact of these heterogeneities by combining experimental design, sketch-based reservoir modelling and flow diagnostics, and they identify the lateral continuity of aeolian sandstones intervals as well as the lateral extent of lacustrine mudstone layers as having the biggest impact on CO 2 migration and retention.…”

Rapid Flow Diagnostics for Prototyping of Reservoir Concepts and Models for Subsurface Co2 Storage

“…Quantifying how the multi-scale geological heterogeneity inherent to many geological formations impacts reservoir behaviour is key to successful CO 2 storage operations, as heterogeneity affects, for example, the available storage volume (Onoja and Shariatipour, 2018), capillary trapping (Harris et al, 2021;Trevisan et al, 2017), CO 2 -brine displacement (Reynolds et al, 2018), and possible leakage paths (Armitage et al, 2011). However, geological heterogeneity in CO 2 storage formations is also inherently uncertain and needs to be explored using reservoir models (Alshakri et al, 2023;Jackson et al, 2022). Lack of adequate uncertainty quantification significantly affects the predictability of reservoir models and subsequent reservoir performance forecasts (Arnold et al, 2016;Bentley and Smith, 2008;Christie et al, 2006).…”

“…these reservoir models in an intuitive and time-effective way (Alshakri et al, 2023;Jackson et al, 2022). The resulting model ensemble can be formally compared using clustering techniques based on specific reservoir performance metrics (Scheidt and Caers, 2009;Watson et al, 2021).…”

“…In this work, we present a novel implementation of the FD simulation routines and underlying computational framework that facilitate CO 2 storage studies in the RRM context during the active injection phase (Alshakri et al, 2023;Jackson et al, 2022). First, new boundary flow conditions are introduced to enable calculation of the storage potential for injected CO 2 .…”

Permeability Characterisation of Sedimentological Facies in the Bunter Sandstone Formation, Endurance CO2 Storage Site, Offshore UK

“…These studies show that permeability heterogeneity occurs at different scales and they are strongly influenced by sedimentary architectures and clay contents, especially in high porosity sandstone units (Prosser et al, 1995;Ringrose et al, 1999;Possemiers et al, 2012). However, only a few studies have been conducted to understand the impact of heterogeneities on CO2 migration in CO2 storage reservoirs (Ambrose et al, 2008;Krevor et al, 2011;Trevisan et al, 2014;Krevor et al, 2015;Li & Benson, 2015;Trevisan et al, 2015;Gershenzon et al, 2017;Krishnamurthy et al, 2017;Trevisan et al, 2017;Krishnamurthy et al, 2022;Alshakri et al, 2023). Core flooding experiments undertaken in these studies primarily aim to understand the capillary trapping at the pore scale, but understanding how these effects propagate into larger scales is still a challenge.…”