Kamaljit Singh

Heriot-Watt University · Institute of GeoEnergy Engineering

Determining the (in)efficiency of wetting phase displacement by an invading non-wetting phase (drainage) in a single fracture is key to modelling upscaled properties such as relative permeability and capillary pressure. These constitutive relationships are fundamental to quantifying the contribution, or lack thereof, of conductive fracture systems...

Investigating the thermoregulation and ventilation processes in termite mound holds great interest, in particular for its potential implications in advancing eco-friendly building designs. In this article we discuss major results on these processes in termite mounds of varying sizes and ventilation types. Additionally, we propose the integration of...

Permeability and heat transport through building materials ultimately dictates their insulatory performance over a buildings service lifetime. Experiments combining XCT with numerical modelling are an accepted method of studying pore scale processes and have been used extensively in the oil and gas industry to study highly complex reservoir rocks....

Subsurface porous rocks hold significant hydrogen (H2) storage potential to support an H2-based energy future. Understanding H2 flow and trapping in subsurface rocks is crucial to reliably evaluate their storage efficiency. In this work, we perform cyclic H2 flow visualization experiments on a layered rock sample with varying pore and throat sizes....

Microporosity is commonly assumed to be non-connected porosity and not commonly studied in geoengineering industry. However, the presence of micropores plays a key role in connecting macropores and it can contribute significantly to the overall flow performance. In this study, targeted CO2 storage carbonate fields in Southeast Asia have significant...

This article discusses the impact of small-scale heterogeneity on pore-scale trapping and displacement of hydrogen in rocks for underground hydrogen storage.

Understanding the pore-scale dynamics and trapping during multiphase flow in porous media is important in many processes such as water infiltration in soils.

Hypothesis Underground hydrogen (H2) storage is a potentially viable solution for large-scale cyclic H2 storage; however, the behavior of H2 at subsurface pressure and temperature conditions is poorly known. This work investigates if the pore-scale displacement processes in H2-brine systems in a porous sandstone can be sufficiently well defined to...

The global commitment to achieve net-zero has led to increasing investment towards the production and usage of green hydrogen (H2).However, the massive quantity needed to match future demand will require new storage facilities. Underground storage of H2 is a potentially viable solution, but poses unique challenges due to the distinctive physical an...

Interfacial tension (IFT) is a crucial parameter in many natural and industrial processes, such as enhanced oil recovery and subsurface energy storage. IFT determines how easy the fluids can pass through pore throats and hence will decide how much residual fluids will be left behind. Here, we use a porous glass micromodel to investigate the dynamic...

Rock fractures provide dominant fluid flow pathways in the Earth’s subsurface and can play an integral role in many subsurface engineering applications, such as the storage of anthropogenic carbon emissions or energy. Injection of an additional fluid into an already saturated fracture, for example, CO2 displacing brine, induces multiphase flow. The...

Hypothesis Imbibition of a fluid into a porous material involves the invasion of a wetting fluid in the pore space through piston-like displacement, film and corner flow, snap-off and pore bypassing. These processes have been studied extensively in two-dimensional (2D) porous systems; however, their relevance to three-dimensional (3D) natural porou...

This study focuses on direct numerical simulation of imbibition, displacement of the non-wetting phase by the wetting phase, through water-wet carbonate rocks. We simulate multiphase flow in a limestone and compare our results with high-resolution synchrotron X-ray images of displacement previously published in the literature by Singh et al. (Sci R...

Deformation bands may show permeabilities that are a few orders of magnitude lower than the surrounding host rocks and therefore have a negative impact on fluid flow in sandstone hydrocarbon reservoirs. Understanding the geometrical attributes of individual bands and their patterns is a critical step in quantifying their connectivity and interpreti...

At the pore scale, slow invasion of a wetting fluid in porous materials is often modeled with quasi‐static approximations which only consider capillary forces in the form of simple pore‐filling rules. The appropriateness of this approximation, often applied in pore network models, is contested in the literature, reflecting the difficulty of predict...

Wettability is a key factor influencing multiphase flow in porous media. In addition to the average contact angle, the spatial distribution of contact angles throughout the porous medium is important, as it directly controls the connectivity of wetting and nonwetting phases. The controlling factors may not only relate to the surface chemistry of mi...

During CO2 storage in depleted oil fields, under immiscible conditions, CO2 can be trapped in the pore space by capillary forces, providing safe storage over geological times - a phenomenon named capillary trapping. Synchrotron X-ray imaging was used to obtain dynamic three-dimensional images of the flow of the three phases involved in this process...

At the pore scale, slow invasion of a wetting fluid in porous materials is often modelled with quasi-static approximations which only consider capillary forces in the form of simple pore filling rules. The appropriateness of this approximation, often applied in pore network models, is contested in literature, reflecting the difficulty of predicting...

Wettability is a key factor influencing multiphase flow in porous media. In addition to the average contact angle, the spatial distribution of contact angles along the porous medium is important, as it directly controls the connectivity of wetting and non-wetting phases. The controlling factors may not only relate to the surface chemistry of minera...

The displacement of a non-wetting fluid by a wetting fluid in porous media, called imbibition, is important in many natural and industrial processes. During imbibition, the wetting fluid invades the pore space through a series of competitions between piston-like displacement, film and corner flow, snap-off, pore bypassing and trapping. Our understa...

Termite nests have been widely studied as effective examples for ventilation and thermoregulation. However, the mechanisms by which these properties are controlled by the microstructure of the outer walls remain unclear. Here, we combine multiscale X-ray imaging with three-dimensional flow field simulations to investigate the impact of the architec...

Plain Language Summary In geological systems, in particular in oil reservoirs, the wetting condition of rock, the preference of a fluid to be in contact with a surface in the presence of another fluid, has a significant impact on multiphase flow. Often a simplified picture based on static, wettability‐dependent fluid configurations is used as a bas...

Liquid invasion into a porous medium is a phenomenon of great importance in both nature and technology. Despite its enormous importance, there is a surprisingly sparse understanding of the processes occurring on the scale of individual pores and of how these processes determine the global invasion pattern. In particular, the exact influence of the...

Multiphase flow in permeable media is a complex pore-scale phenomenon, which is important in many natural and industrial processes. To understand the pore-scale dynamics of multiphase flow, we acquired time-series synchrotron X-ray micro-tomographic data at a voxel-resolution of 3.28 μm and time-resolution of 38 s during drainage and imbibition in...

One of the major concerns of carbon capture and storage (CCS) projects is the prediction of the long-term storage security of injected CO2. When injected underground in saline aquifers or depleted oil and gas fields, CO2 mixes with the resident brine to form carbonic acid. The carbonic acid can react with the host carbonate rock, and alter the rock...

X-ray micro-tomography is used to image the pore-scale configurations of fluid in a rock saturated with three phases - brine, oil and gas - mimicking a subsurface reservoir, at high pressure and temperature. We determine pore occupancy during a displacement sequence that involves waterflooding, gas injection and water re-injection. In the water-wet...

Wettability is an important factor which controls the displacement of immiscible fluids in permeable media, with far reaching implications for storage of CO2 in deep saline aquifers, fuel cells, oil recovery, and for the remediation of oil contaminated soils. Considering the paradigmatic case of random piles of spherical beads, fluid front morpholo...

We used X-ray micro-tomography to image the in situ wettability, the distribution of contact angles, at the pore scale in calcite cores from a producing hydrocarbon reservoir at subsurface conditions. The contact angle was measured at hundreds of thousands of points for three samples after twenty pore volumes of brine flooding.We found a wide range...

Understanding the pore-scale dynamics of two-phase fluid flow in permeable media is important in many processes such as water infiltration in soils, oil recovery, and geo-sequestration of CO2. The two most important processes that compete during the displacement of a non-wetting fluid by a wetting fluid are pore-filling or piston-like displacement...

Multiphase flow in porous media is strongly influenced by the wettability of the system, which affects the arrangement of the interfaces of different phases residing in the pores. We present a method for estimating the effective contact angle, which quantifies the wettability and controls the local capillary pressure within the complex pore space o...

The structure and connectivity of the pore space during the pyrolysis of oil shales determines hydrocarbon flow behavior and ultimate recovery. We image the time evolution of the pore and microfracture networks during oil shale pyrolysis using synchrotron X-ray microtomography. Immature Green River (Mahogany Zone) shale samples were thermally matur...

We have investigated the effect of wettability of carbonate rocks on the morphologies of remaining oil after sequential oil and brine injection in a capillary-dominated flow regime at elevated pressure. The wettability of Ketton limestone was altered in-situ using an oil phase doped with fatty acid which produced mixed-wet conditions (the contact a...

Large scale faults are important structural elements within many conventional clastic reservoirs, acting as potential conduits, baffles or barriers to hydrocarbon or CO2 migration. Though inconspicuous within most seismic tomography datasets, smaller subsidiary faults, commonly within the damage zones of parent structures, may also play an importan...

The frequent use of non-aqueous phase liquids (NAPLs) in cold regions creates serious risks of soil and groundwater contamination. NAPL contaminants can stay in soil for long times due to their entrapment by strong interfacial forces, resulting in a source of pollution caused by their slow dissolution in groundwater over decades. The presence of th...

The pore-scale behavior of a nonaqueous phase liquid (NAPL) trapped as residual contamination in a porous medium, subject to freeze-thaw cycles, was investigated by X-ray microcomputed tomography. It is shown that freeze-thaw cycles cause significant NAPL remobilization in the direction of the freezing front, due to the rupture and transport of a s...

Experiments were conducted on dodecane at residual saturation (21-26%) in a two-dimensional water-saturated glass bead cell (0.5 mm diameter)--to simulate light nonaqueous phase liquid (LNAPL) trapped below the water table--subject to controlled freeze-thaw cycles. The experiments reveal substantial remobilization and rupture of LNAPL ganglia durin...