Gillian Pickup - Academia.edu (original) (raw)

Papers by Gillian Pickup

Day 4 Thu, November 05, 2020, 2020

In any flooding process, the flow pattern determines the quality of the macroscopic sweep and exp... more In any flooding process, the flow pattern determines the quality of the macroscopic sweep and expected recovery efficiency. The flow pattern also controls the choice of the flooding strategy. This study compares CO2 flow patterns between two major classes of reservoirs; first, the United States CO2 flooded reservoirs, considered as benchmark for CO2 application elsewhere, and second, the North Sea class of reservoirs considered as future target for CO2 flooding offshore. An inventory of reservoir data was first prepared by inspecting the literature. North Sea reservoirs are characterised with higher temperatures, higher pressures, thicker pays and higher permeabilities. Well spacing is also larger in the North Sea and these reservoirs are depleted faster. Using appropriate correlations, the in-situ CO2 and oil properties were inferred for each individual reservoir knowing its ambient reservoir conditions. Scaling analysis was used to characterise the CO2 displacing oil process in ea...

Preliminary studies from CO2-EOR in Canada have suggested that, in CO2-EOR settings, solubility t... more Preliminary studies from CO2-EOR in Canada have suggested that, in CO2-EOR settings, solubility trapping takes place within both aqueous and hydrocarbon phases. As such it is postulated that CO2-EOR may provide a greater quantity of securely stored CO2 than a purely non-EOR storage operation. This study's principal objective was to quantify how much solubility trapping takes place within both aqueous and hydrocarbon phases in CO2-EOR settings. The Pembina Cardium CO2 Monitoring Pilot Project was used as a test site to determine the relative roles of solubility trapping. Firstly two geochemical approaches using empirical data from the site (gas geochemistry, production volumes and water isotope geochemistry) were used to determine the phase distribution of CO2 (dissolved or free phase) at a number of production wells that were sampled monthly during a two-year CO2 injection pilot. In addition a simplified reservoir simulation was performed to use it as a test-bed to investigate v...

SPE Reservoir Evaluation & Engineering, 2021

SummaryCarbon dioxide (CO2) enhanced oil recovery (EOR) has long been practiced in the US as an e... more SummaryCarbon dioxide (CO2) enhanced oil recovery (EOR) has long been practiced in the US as an efficient mean for enhancing oil production. Many of the US CO2-EOR developments have been designed horizontally. This is because of a viscous-dominated CO2 flow regime that is prevalent in these developments driven by thin and low-permeability reservoirs. Reservoirs and fluid properties are different in the North Sea. Pays are usually thicker with better petrophysical properties. Lighter oils can also be found in North Sea reservoirs. This suggests that a dissimilar flow regime might prevail CO2 displacements in the North Sea developments, which could favor a dissimilar CO2-EOR process design. This study thus compares CO2 flow regimes between several North Sea and US reservoirs. We use scaling analysis to characterize and compare CO2 flow regimes between these two classes of reservoirs. Scaling analysis characterizes CO2 displacement in each reservoir system using three dimensionless num...

International Journal of Greenhouse Gas Control, 2016

In this proposed CO2 injection system, brine is extracted from the target storage aquifer by mean... more In this proposed CO2 injection system, brine is extracted from the target storage aquifer by means of a lateral horizontal completion located near the top of the formation. It should be noted that the brine is not lifted to the surface. An Electrical Submersible Pump (ESP) is used to extract the brine and boost its pressure, before it is mixed with CO2 that is injected down the vertical section of the well. The mixing takes place in the vertical section of the well below the upper lateral. The CO2brine mix is then injected into the same formation through a lower lateral. A down-hole tool would be used to maximise agitation and contact area between CO2 and brine in the vertical mixing section of the well, which may be tens to hundreds of metres long, depending on the thickness of the formation. The advantages of this method are that there is little overall pressure increase, because CO2 is mixed with brine extracted from the formation, and also the extracted brine is already at high pressure when it is mixed with the CO2, greatly increasing the solubility of CO2 and reducing the volume of brine required. Energy is not expended lifting the brine to surface nor is there any concern about handling large volumes of acidic brine in the surface equipment. In this study, in addition to the concept of the down-hole mixing (DHM) method which is presented, the application of the DHM method in a hypothetical storage site (Lincolnshire-Smith et al., 2012) is also examined. The calculations are performed to identify the optimum rates of water extraction and injection of dissolved CO2 in brine. Introduction: Since the industrial revolution, the CO2 concentration in the atmosphere has increased by 45% (Celia et al., 2015). At the current time, it is believed that carbon capture and storage (CCS) can play a significant role in reducing the increase in the CO2 concentration in the atmosphere (Haszeldine, 2009). In the long term, several trapping mechanisms such as structural and stratigraphic trapping, residual trapping, solubility trapping and mineral trapping can be used to sequester supercritical CO2 into the aquifers or depleted reservoirs (Benson and Cole 2008). Structural trapping to prevent upward migration of CO2 is provided by a very low permeability layer, which is frequently a clay or shale layer, at the top of the storage formation. Safe long-term CO2 storage has been one of the most important issues, in

International Journal of Greenhouse Gas Control, 2016

When investigating the storage of CO2 in deep saline formations, many studies assume a smooth, ab... more When investigating the storage of CO2 in deep saline formations, many studies assume a smooth, abrupt interface between the storage and the sealing formations. Typically, though, the surface is irregular, due to sedimentological and stratigraphic effects or structural deformation. In this study, the area where the CO2 migrates beneath the caprock is investigated. A set of numerical simulations were conducted to investigate the impacts of various factors on CO2 storage, such as top morphology, tilt, kv/kh ratio and the presence of a transition zone, where there is a gradational change from storage formation to caprock. In the models tested, the kv/kh ratio was most important during the injection period, but after injection ceased, the tilt was more important. The amplitude of the ridges, which were used to represent the top morphology, did not have a large effect but, as expected hindered or encouraged migration depending on whether they were perpendicular or parallel to the tilt. A transition zone can increase the security of storage by lessening the amount of CO2 accumulating underneath the caprock. Therefore it is important to characterise the interface in terms of the size of irregularities and also in terms of the existence of any transition zone. The latter has not been addressed in previous works. A simple formula was derived to predict the limiting tilt for trapping to occur in models with a sinusoidal interface with wavelength, , and amplitude, A. Although this is a simplified approach, it provides a means of assessing whether the topography of the top surface will give rise to significant trapping or not.

Petroleum Geoscience, 2016

This document is the author's post-print version, incorporating any revisions agreed during the p... more This document is the author's post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it.

ECMOR IV - 4th European Conference on the Mathematics of Oil Recovery, 1994

In order to capture the effects of all the levels of geological heterogeneity on a fluid displace... more In order to capture the effects of all the levels of geological heterogeneity on a fluid displacement process at the larger scale, it is necessary to use scaleup techniques. These should reproduce the results of fine grid calculations on a coarser grid. Conventional reservoir simulation practice has referred to these techniques as pseudo-isation, and the main objective has been to produce pseudo-functions (or effective flow functions) which can be used on the coarse grid. When carried out successfully, the pseudo-functions (e.g. pseudo relative permeabilities) incorporate the interaction between the fluid mechanics and the heterogeneity as well as correcting for numerical dispersion. These pseudo-functions are also parameterised by the scaling groups under which the fine grid displacement was carried out (i.e. viscous/capillary and viscous/gravity ratio and certain geometrical scaling groups) and are valid for the boundary conditions relevant to the particular flows.

AAPG Bulletin, 1993

We have used a coastal outcrop of Lower Carboniferous deltaic and shallow-marine sediments to ill... more We have used a coastal outcrop of Lower Carboniferous deltaic and shallow-marine sediments to illustrate reservoir flow process. We show how the sediment architecture (rippled and cross-bedded lamination and intraformational faulting) influences the effective permeability at various scales, and derive tensor permeabilities for the different architecture types. Pervasive cross-lamination can produce significant cross flow, the degree of which is determined by the internal permeability contrasts and external boundary conditions (such as the presence of shale above and below). When two immiscible phases are flowing, the sediment architecture can generate additional anisotropy in the relative permeability functions of the two phases. This results in varying amounts of trapping of the nonwetting phase, depending on the flow direction with respect to the sediment architecture or fracture fabric. The waterflood behavior of the formations observed in the cliff (10 m x 100 m ) is modeled, using a data set based on probe permeameter measurements taken from two vertical transects representing boreholes. We contrast the degree of oil recovery from the formation when different assumptions are made: (a) using averaged borehole data and no geological structure, (b) using traditional geostatistical methods to extrapolate from the borehole data, and (c) modeling the sediment architecture of the interwell volume using mixed stochastic/deterministic methods. We find that, in most cases, the sediment architecture has an important effect on flow performance. Differences in predicted oil recovery of up to 20% can occur when these small-scale effects are correctly modeled. Traditional reservoir engineering methods, using average permeability values, only prove acceptable in high-permeability/low-heterogeneity zones.

Proceedings of SPE Reservoir Simulation Symposium, 1999

This paper was prepared for presentation at the 1999 SPE Reservoir Simulation Symposium held in H... more This paper was prepared for presentation at the 1999 SPE Reservoir Simulation Symposium held in Houston, Texas, 14-17 February 1999.

Journal of Natural Gas Science and Engineering

Transport in Porous Media

This study seeks to improve numerical simulations of the key physics occurring in CO2 enhanced oi... more This study seeks to improve numerical simulations of the key physics occurring in CO2 enhanced oil recovery (CO2-EOR) processes, with a particular focus on the transition from immiscible to miscible displacements. In the previous work, we have investigated interactions between compositional effects and the underlying heterogeneities of the flow field in near-miscible floods (Wang et al. in Transp Porous Media 129(3):743–759, 2019a). In this current study, we have further analysed the effects of reduction in interfacial tension (IFT) on the flow behaviour, as motivated by the study on the film-flow mechanism previously presented by Sorbie and van Dijke (SPE improved oil recovery symposium, Society of Petroleum Engineers, 2010). We identify two clear mechanisms of oil recovery that may occur in near-miscible CO2 (or other gas) injection processes, which we denote, MCE, as oil stripping or conventional compositional effects, and MIFT as lower IFT oil film-flow effects. The latter MIFT ...

SPE Reservoir Simulation Conference

... Project has developed and applied a number of methods of flow simulation and upscaling, inclu... more ... Project has developed and applied a number of methods of flow simulation and upscaling, including the Geopseudo Method (eg Corbett et al., 1992; Ringrose et al., 1993; Huang et al., 1995; Ringrose et al., 1999; Pickup et al., 2000; Pickup and Stephen, 2000; Stephen and ...

Mathematical Geology, Jan 31, 1994

Accurate modeling of fluid flow through sedimentary, units is of great importance in assessing th... more Accurate modeling of fluid flow through sedimentary, units is of great importance in assessing the performance of both hydrocarbon reservoirs and aquifers. Most sedimentary rocks display structure from the mm or cm scale upwards. Flow simulation should therefore begin with grid blocks of this size in order to calculate effective permeabilities for larger structures. In this paper, we investigate several flow models for sandstones, and examine their impact on the calculation of effective perme-abili~, for single phase flow. Crossflow arises in some structures, in which case it may be necessary to use a tensor representation of the effective permeability. We establish conditions under which tensors are required, e.g., in crossbedded structures with a high bedding angle, high permeability contrast, and laminae of comparable thickness. Cases where the off-diagonal terms can be neglected, such as in symmetrical systems, are also illustrated. We indicate how the method of calculating tensor permeabilities may be extended to model multiphase flow in sedimentar 3, structurfs.

Transport in Porous Media, 2005

... that water travels preferentially through the low permeability regions, leaving oil trapped i... more ... that water travels preferentially through the low permeability regions, leaving oil trapped in the high permeability zones (eg Ringrose et al ... Although the balance of forces varies throughout a flood (Stephen et al., 2001), capillary numbers are useful for approximate calculations. ...

International Journal of Greenhouse Gas Control, 2015

We combine reservoir simulation with 2D synthetic seismic reflection time-lapse data to assess th... more We combine reservoir simulation with 2D synthetic seismic reflection time-lapse data to assess the ability of seismic methods to image plume growth, evolution, and migration within a heterogeneous saline reservoir. The incorporation of reservoir heterogeneity results in a range of saturations due to the tortuous migration around the intra-reservoir baffles. To account for the disruptive nature of the injected CO2, and the uncertainties regarding the fluid saturation distribution, we use two end-member models, uniform and patchy, to generate the widest range of seismic velocity distributions to understand the range of velocity-saturation behaviour which could be encountered. The generated seismic sections show clear differences between the two models while also providing confidence in the ability to detect CO2 plume growth and evolution in the reservoir. A free-phase migrating front of CO2 appears to be difficult to detect, however. The ability to image a front is shown to be dependent not only on the pore-fluid saturation distribution-patchy or uniform-but also on its larger-scale spatial geometry. As the subtle change in amplitude is directly related to the concentration of CO2 within each accumulation, it suggests that the saturation model has important implications for CO2 detectability and for quantifying the volume of CO2 injected into the reservoir.

Day 4 Thu, November 05, 2020, 2020

In any flooding process, the flow pattern determines the quality of the macroscopic sweep and exp... more In any flooding process, the flow pattern determines the quality of the macroscopic sweep and expected recovery efficiency. The flow pattern also controls the choice of the flooding strategy. This study compares CO2 flow patterns between two major classes of reservoirs; first, the United States CO2 flooded reservoirs, considered as benchmark for CO2 application elsewhere, and second, the North Sea class of reservoirs considered as future target for CO2 flooding offshore. An inventory of reservoir data was first prepared by inspecting the literature. North Sea reservoirs are characterised with higher temperatures, higher pressures, thicker pays and higher permeabilities. Well spacing is also larger in the North Sea and these reservoirs are depleted faster. Using appropriate correlations, the in-situ CO2 and oil properties were inferred for each individual reservoir knowing its ambient reservoir conditions. Scaling analysis was used to characterise the CO2 displacing oil process in ea...

Preliminary studies from CO2-EOR in Canada have suggested that, in CO2-EOR settings, solubility t... more Preliminary studies from CO2-EOR in Canada have suggested that, in CO2-EOR settings, solubility trapping takes place within both aqueous and hydrocarbon phases. As such it is postulated that CO2-EOR may provide a greater quantity of securely stored CO2 than a purely non-EOR storage operation. This study's principal objective was to quantify how much solubility trapping takes place within both aqueous and hydrocarbon phases in CO2-EOR settings. The Pembina Cardium CO2 Monitoring Pilot Project was used as a test site to determine the relative roles of solubility trapping. Firstly two geochemical approaches using empirical data from the site (gas geochemistry, production volumes and water isotope geochemistry) were used to determine the phase distribution of CO2 (dissolved or free phase) at a number of production wells that were sampled monthly during a two-year CO2 injection pilot. In addition a simplified reservoir simulation was performed to use it as a test-bed to investigate v...

SPE Reservoir Evaluation & Engineering, 2021

SummaryCarbon dioxide (CO2) enhanced oil recovery (EOR) has long been practiced in the US as an e... more SummaryCarbon dioxide (CO2) enhanced oil recovery (EOR) has long been practiced in the US as an efficient mean for enhancing oil production. Many of the US CO2-EOR developments have been designed horizontally. This is because of a viscous-dominated CO2 flow regime that is prevalent in these developments driven by thin and low-permeability reservoirs. Reservoirs and fluid properties are different in the North Sea. Pays are usually thicker with better petrophysical properties. Lighter oils can also be found in North Sea reservoirs. This suggests that a dissimilar flow regime might prevail CO2 displacements in the North Sea developments, which could favor a dissimilar CO2-EOR process design. This study thus compares CO2 flow regimes between several North Sea and US reservoirs. We use scaling analysis to characterize and compare CO2 flow regimes between these two classes of reservoirs. Scaling analysis characterizes CO2 displacement in each reservoir system using three dimensionless num...

International Journal of Greenhouse Gas Control, 2016

In this proposed CO2 injection system, brine is extracted from the target storage aquifer by mean... more In this proposed CO2 injection system, brine is extracted from the target storage aquifer by means of a lateral horizontal completion located near the top of the formation. It should be noted that the brine is not lifted to the surface. An Electrical Submersible Pump (ESP) is used to extract the brine and boost its pressure, before it is mixed with CO2 that is injected down the vertical section of the well. The mixing takes place in the vertical section of the well below the upper lateral. The CO2brine mix is then injected into the same formation through a lower lateral. A down-hole tool would be used to maximise agitation and contact area between CO2 and brine in the vertical mixing section of the well, which may be tens to hundreds of metres long, depending on the thickness of the formation. The advantages of this method are that there is little overall pressure increase, because CO2 is mixed with brine extracted from the formation, and also the extracted brine is already at high pressure when it is mixed with the CO2, greatly increasing the solubility of CO2 and reducing the volume of brine required. Energy is not expended lifting the brine to surface nor is there any concern about handling large volumes of acidic brine in the surface equipment. In this study, in addition to the concept of the down-hole mixing (DHM) method which is presented, the application of the DHM method in a hypothetical storage site (Lincolnshire-Smith et al., 2012) is also examined. The calculations are performed to identify the optimum rates of water extraction and injection of dissolved CO2 in brine. Introduction: Since the industrial revolution, the CO2 concentration in the atmosphere has increased by 45% (Celia et al., 2015). At the current time, it is believed that carbon capture and storage (CCS) can play a significant role in reducing the increase in the CO2 concentration in the atmosphere (Haszeldine, 2009). In the long term, several trapping mechanisms such as structural and stratigraphic trapping, residual trapping, solubility trapping and mineral trapping can be used to sequester supercritical CO2 into the aquifers or depleted reservoirs (Benson and Cole 2008). Structural trapping to prevent upward migration of CO2 is provided by a very low permeability layer, which is frequently a clay or shale layer, at the top of the storage formation. Safe long-term CO2 storage has been one of the most important issues, in

International Journal of Greenhouse Gas Control, 2016

When investigating the storage of CO2 in deep saline formations, many studies assume a smooth, ab... more When investigating the storage of CO2 in deep saline formations, many studies assume a smooth, abrupt interface between the storage and the sealing formations. Typically, though, the surface is irregular, due to sedimentological and stratigraphic effects or structural deformation. In this study, the area where the CO2 migrates beneath the caprock is investigated. A set of numerical simulations were conducted to investigate the impacts of various factors on CO2 storage, such as top morphology, tilt, kv/kh ratio and the presence of a transition zone, where there is a gradational change from storage formation to caprock. In the models tested, the kv/kh ratio was most important during the injection period, but after injection ceased, the tilt was more important. The amplitude of the ridges, which were used to represent the top morphology, did not have a large effect but, as expected hindered or encouraged migration depending on whether they were perpendicular or parallel to the tilt. A transition zone can increase the security of storage by lessening the amount of CO2 accumulating underneath the caprock. Therefore it is important to characterise the interface in terms of the size of irregularities and also in terms of the existence of any transition zone. The latter has not been addressed in previous works. A simple formula was derived to predict the limiting tilt for trapping to occur in models with a sinusoidal interface with wavelength, , and amplitude, A. Although this is a simplified approach, it provides a means of assessing whether the topography of the top surface will give rise to significant trapping or not.

Petroleum Geoscience, 2016

This document is the author's post-print version, incorporating any revisions agreed during the p... more This document is the author's post-print version, incorporating any revisions agreed during the peer-review process. Some differences between the published version and this version may remain and you are advised to consult the published version if you wish to cite from it.

ECMOR IV - 4th European Conference on the Mathematics of Oil Recovery, 1994

In order to capture the effects of all the levels of geological heterogeneity on a fluid displace... more In order to capture the effects of all the levels of geological heterogeneity on a fluid displacement process at the larger scale, it is necessary to use scaleup techniques. These should reproduce the results of fine grid calculations on a coarser grid. Conventional reservoir simulation practice has referred to these techniques as pseudo-isation, and the main objective has been to produce pseudo-functions (or effective flow functions) which can be used on the coarse grid. When carried out successfully, the pseudo-functions (e.g. pseudo relative permeabilities) incorporate the interaction between the fluid mechanics and the heterogeneity as well as correcting for numerical dispersion. These pseudo-functions are also parameterised by the scaling groups under which the fine grid displacement was carried out (i.e. viscous/capillary and viscous/gravity ratio and certain geometrical scaling groups) and are valid for the boundary conditions relevant to the particular flows.

AAPG Bulletin, 1993

We have used a coastal outcrop of Lower Carboniferous deltaic and shallow-marine sediments to ill... more We have used a coastal outcrop of Lower Carboniferous deltaic and shallow-marine sediments to illustrate reservoir flow process. We show how the sediment architecture (rippled and cross-bedded lamination and intraformational faulting) influences the effective permeability at various scales, and derive tensor permeabilities for the different architecture types. Pervasive cross-lamination can produce significant cross flow, the degree of which is determined by the internal permeability contrasts and external boundary conditions (such as the presence of shale above and below). When two immiscible phases are flowing, the sediment architecture can generate additional anisotropy in the relative permeability functions of the two phases. This results in varying amounts of trapping of the nonwetting phase, depending on the flow direction with respect to the sediment architecture or fracture fabric. The waterflood behavior of the formations observed in the cliff (10 m x 100 m ) is modeled, using a data set based on probe permeameter measurements taken from two vertical transects representing boreholes. We contrast the degree of oil recovery from the formation when different assumptions are made: (a) using averaged borehole data and no geological structure, (b) using traditional geostatistical methods to extrapolate from the borehole data, and (c) modeling the sediment architecture of the interwell volume using mixed stochastic/deterministic methods. We find that, in most cases, the sediment architecture has an important effect on flow performance. Differences in predicted oil recovery of up to 20% can occur when these small-scale effects are correctly modeled. Traditional reservoir engineering methods, using average permeability values, only prove acceptable in high-permeability/low-heterogeneity zones.

Proceedings of SPE Reservoir Simulation Symposium, 1999

This paper was prepared for presentation at the 1999 SPE Reservoir Simulation Symposium held in H... more This paper was prepared for presentation at the 1999 SPE Reservoir Simulation Symposium held in Houston, Texas, 14-17 February 1999.

Journal of Natural Gas Science and Engineering

Transport in Porous Media

This study seeks to improve numerical simulations of the key physics occurring in CO2 enhanced oi... more This study seeks to improve numerical simulations of the key physics occurring in CO2 enhanced oil recovery (CO2-EOR) processes, with a particular focus on the transition from immiscible to miscible displacements. In the previous work, we have investigated interactions between compositional effects and the underlying heterogeneities of the flow field in near-miscible floods (Wang et al. in Transp Porous Media 129(3):743–759, 2019a). In this current study, we have further analysed the effects of reduction in interfacial tension (IFT) on the flow behaviour, as motivated by the study on the film-flow mechanism previously presented by Sorbie and van Dijke (SPE improved oil recovery symposium, Society of Petroleum Engineers, 2010). We identify two clear mechanisms of oil recovery that may occur in near-miscible CO2 (or other gas) injection processes, which we denote, MCE, as oil stripping or conventional compositional effects, and MIFT as lower IFT oil film-flow effects. The latter MIFT ...

SPE Reservoir Simulation Conference

... Project has developed and applied a number of methods of flow simulation and upscaling, inclu... more ... Project has developed and applied a number of methods of flow simulation and upscaling, including the Geopseudo Method (eg Corbett et al., 1992; Ringrose et al., 1993; Huang et al., 1995; Ringrose et al., 1999; Pickup et al., 2000; Pickup and Stephen, 2000; Stephen and ...

Mathematical Geology, Jan 31, 1994

Accurate modeling of fluid flow through sedimentary, units is of great importance in assessing th... more Accurate modeling of fluid flow through sedimentary, units is of great importance in assessing the performance of both hydrocarbon reservoirs and aquifers. Most sedimentary rocks display structure from the mm or cm scale upwards. Flow simulation should therefore begin with grid blocks of this size in order to calculate effective permeabilities for larger structures. In this paper, we investigate several flow models for sandstones, and examine their impact on the calculation of effective perme-abili~, for single phase flow. Crossflow arises in some structures, in which case it may be necessary to use a tensor representation of the effective permeability. We establish conditions under which tensors are required, e.g., in crossbedded structures with a high bedding angle, high permeability contrast, and laminae of comparable thickness. Cases where the off-diagonal terms can be neglected, such as in symmetrical systems, are also illustrated. We indicate how the method of calculating tensor permeabilities may be extended to model multiphase flow in sedimentar 3, structurfs.

Transport in Porous Media, 2005

... that water travels preferentially through the low permeability regions, leaving oil trapped i... more ... that water travels preferentially through the low permeability regions, leaving oil trapped in the high permeability zones (eg Ringrose et al ... Although the balance of forces varies throughout a flood (Stephen et al., 2001), capillary numbers are useful for approximate calculations. ...

International Journal of Greenhouse Gas Control, 2015

We combine reservoir simulation with 2D synthetic seismic reflection time-lapse data to assess th... more We combine reservoir simulation with 2D synthetic seismic reflection time-lapse data to assess the ability of seismic methods to image plume growth, evolution, and migration within a heterogeneous saline reservoir. The incorporation of reservoir heterogeneity results in a range of saturations due to the tortuous migration around the intra-reservoir baffles. To account for the disruptive nature of the injected CO2, and the uncertainties regarding the fluid saturation distribution, we use two end-member models, uniform and patchy, to generate the widest range of seismic velocity distributions to understand the range of velocity-saturation behaviour which could be encountered. The generated seismic sections show clear differences between the two models while also providing confidence in the ability to detect CO2 plume growth and evolution in the reservoir. A free-phase migrating front of CO2 appears to be difficult to detect, however. The ability to image a front is shown to be dependent not only on the pore-fluid saturation distribution-patchy or uniform-but also on its larger-scale spatial geometry. As the subtle change in amplitude is directly related to the concentration of CO2 within each accumulation, it suggests that the saturation model has important implications for CO2 detectability and for quantifying the volume of CO2 injected into the reservoir.