Bulletin of Chemical Reaction Engineering & Catalysis
Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP)... more Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP) floods and this silicate scale deposition affects oil production. Hence, it is important to examine the conditions that lead to silicate scale forming. The severity of the silicate scaling reaction, the type and morphology of silica/silicate scale formed in an experimental ASP flood were studied for pH values 5, 8.5, and 11, whilst the temperature was kept constant at 90 ℃. In addition, the impact of calcium ion was studied and spectroscopic analyses were used to identify the extent of scaling reaction, morphology type and the functional group present in the precipitates. This was performed using imagery of the generated precipitates. It was observed that the silica/silicate scale is most severe at the highest pH and Ca:Mg molar ratios examined. Magnesium hydroxide and calcium hydroxide were observed to precipitate along with the silica and Mg-silicate/Ca-silicate scale at pH 11. The pr...
Scale inhibition efficiency is determined in bulk jar tests in order to determine a minimum inhib... more Scale inhibition efficiency is determined in bulk jar tests in order to determine a minimum inhibitor concentration (MIC) which gives some acceptable level of inhibition (say 95%). However, this test refers principally to the bulk precipitation of barium mineral scale from solution, rather than its deposition on a surface. The complementary tube blocking test gives some insight into scale adhesion at a surface, but this is a very short residence time test. An experimental study has been conducted to examine the interactions between surface and bulk BaSO4 scaling processes in uninhibited and inhibited supersaturated brines. In this study, precipitation both in bulk and onto a Hastelloy metal surface has been studied in longer term bulk jar tests at various temperatures. It has been demonstrated that the use of PPCA at concentrations beneath the MIC level, as determined by bulk jar tests, can promote surface scaling. This comes about as a result of complex interactions between bulk pr...
In the application of chemical inhibitors in field squeeze treatments for the prevention of sulph... more In the application of chemical inhibitors in field squeeze treatments for the prevention of sulphate and carbonate mineral scale formation, it is very important that the chemical species involved can be accurately assayed. When the inhibitor concentration drops below a predetermined threshold level for scale inhibition (Ct) then the well may need to be resqueezed. The accurate assay of scale inhibitors down to concentration levels of a few ppm in real field brines can be a difficult task. In this paper, we examine a number of interferences which often make assay techniques very difficult to apply in field produced brines. The inhibitors examined in this work include phosphonates (PH), polyacrylates (PAA) and phosphino-polycarboxylates (PPCA). The main objective of this work is to develop suitable pre-treatment/purification techniques which allow the standard wet chemical techniques to be applied effectively after appropriate modification. Successful techniques - all based on careful...
Summary Using chemical scale inhibitors is one of the most common methods of preventing downhole ... more Summary Using chemical scale inhibitors is one of the most common methods of preventing downhole and topside mineral scale formation in oil fields. Several aspects of the brine composition may affect the performance of the various scale inhibitors. In this paper, we focus on the roles of calcium and magnesium ion concentrations. The calcium concentration in a particular reservoir and in the inhibitor slug often determines the extent to which the inhibitor species is retained in the near-wellbore area (i.e., on its adsorption or precipitation behavior). What is less well understood is the effect of divalent cations on the inhibition process itself. Common ion effects are well known; however, for pentaphosphonate inhibitor species (e.g., DETPMP), significant improvements in inhibition efficiency have been reported by increasing the calcium concentration in the solution. In this paper, we expand significantly on such observations. The effect of calcium and magnesium cation concentratio...
This study investigates the interaction of compositional effects with the flow behaviour during n... more This study investigates the interaction of compositional effects with the flow behaviour during near-miscible (and immiscible) CO 2-oil displacements in heterogeneous systems. A series of numerical simulations modelling 1D slim-tube and 2D areal systems were simulated using a fully compositional simulator. A number of grid resolutions for a slimtube model were simulated to choose the proper level of numerical dispersion to mimic the actual physical dispersion. The corresponding 2D cases are based on a small heterogeneous sector model of dimensions 50 m × 10 m, in order that the fine-scale displacement physics can be modelled accurately. We investigated various flow regimes ranging from viscous fingering to channelling displacements within heterogeneous random correlated fields. We found that the reduced recovery is the result of a combination of differences in sweep efficiency associated with the viscous fingering and possible differences in local mixing that affect composition path. At the same time, the unstable phase flow determined by the underlying heterogeneity slows the flow in the unswept area and leads to unequal displacement performance between preferential and non-preferential routes. Specifically, lighter components have moved preferentially in high gas saturation zones, and leaving the heavier components behind in slower flow zones. In the case of channelling flow, compositional effects were less important since the permeability channel dominated the displacement. Both the ultimate oil recovery and component recovery are significantly and about equally reduced, when the underlying heterogeneity is of dominant influence. To summarise, compositional effects can have a very significant impact on the prediction of near-miscible CO 2 EOR projects. Issues such as front stability, local displacement efficiency and formation of fingering/channelling during CO 2 near-miscible displacement can lead to behaviour that is significantly different from immiscible flooding in these systems. The process of mass transfer between CO 2 and oil can be hampered to a certain degree by unstable flow depending on the level of heterogeneity. This leads to a further reduction in component recovery, particularly of the heavier components. The complete dataset and results of this study are available online as a model case example for compositional flows in heterogeneous systems (Wang et al. in "The analysis of compositional effects on global flow regimes in CO 2 nearmiscible displacements in heterogeneous systems" dataset for paper SPE
Pore networks can be extracted from 3D rock images to accurately predict multiphase flow properti... more Pore networks can be extracted from 3D rock images to accurately predict multiphase flow properties of rocks by network flow simulation. However, the predicted flow properties may be sensitive to the extracted pore network if it is small, even though its underlying characteristics are representative. Therefore, it is a challenge to investigate the effects on flow properties of microscopic rock features individually and collectively based on small samples. In this article, a new approach is introduced to generate from an initial network a stochastic network of arbitrary size that has the same flow properties as the parent network. Firstly, we characterise the realistic parent network in terms of distributions of the geometrical pore properties and correlations between these properties, as well as the connectivity function describing the detailed network topology. Secondly, to create a stochastic network of arbitrary size, we generate the required number of nodes and bonds with the correlated properties of the original network. The nodes are randomly located in the given network domain and connected by bonds according to the strongest correlation between node and bond properties, while honouring the connectivity function. Thirdly, using a state-of-the-art two-phase flow network model, we demonstrate for two samples that the rock flow properties (capillary pressure, absolute and relative permeability) are preserved in the stochastic networks, in particular, if the latter are larger than the original, or the method reveals that the size of the original sample is not representative. We also show the information that is necessary to reproduce the realistic networks correctly, in particular the connectivity function. This approach forms the basis for the stochastic generation of networks from multiple rock images at different resolutions by combining the relevant statistics from the corresponding networks, which will be presented in a future publication.
The oil industry is currently facing severe restrictions concerning the discharge of oilfield che... more The oil industry is currently facing severe restrictions concerning the discharge of oilfield chemicals into the environment. The purpose of this study is to test the possibility of replacing an organic phosphonate scale inhibitor (DETPMP) by a more environmentally friendly “green” species: carboxymethyl inulin (CMI). Although, promising these results are nevertheless far inferior to the performance exhibited by the DETPMP
In a cylindrical pore of arbitrary wettability, we analyse the existence of a three-fluid contact... more In a cylindrical pore of arbitrary wettability, we analyse the existence of a three-fluid contact line connecting the fluid-fluid interfaces between two bulk phases and the third phase contained in a cusp near the pore wall. This analysis is supported by the very similar, but simpler, analysis for a constriction between parallel plates. From the force balance at the contact line and the equations for the interface curvatures we derive expressions for the cusp height and for the capillary entry pressure related to piston-like displacement between the two bulk phases. The latter is independent of the existence of a cusp and its phase pressure. Based on some realistic assumptions, of which the most important is that a cusp grows continuously from the onset when its phase pressure is increased, we analyse under which conditions a cusp can exist, and, when it exists, what its behaviour is as a function of the cusp phase pressure. We find a simple criterion involving (two ratios of) the three interfacial tensions and two of the three contact angles, which determines whether the three-fluid contact line and, consequently, a cusp exists. The range of contact angles, as well as the size of the cusp increases, when the cusp phase is close to spreading. Not only cusps of the wetting phase can occur, but also of the intermediate-wetting phase. Numerical examples are presented to illustrate the range of behaviour of the cusps.
In this work we derive rigorously the free energy balance for three fluid phases in a straight ca... more In this work we derive rigorously the free energy balance for three fluid phases in a straight capillary of arbitrarily shaped cross-section. This balance is then used to derive the general equation for the capillary entry pressures of all possible two-phase and three-phase displacements. Moreover, the equation provides the criterion determining the existence of layers of the intermediate-wetting phase separating the wetting and non-wetting phases in the corners or cavities of a capillary, by also treating the spreading of such layers as a capillary displacement. For a number of combinations of interfacial tensions and contact angles, illustrating all the different relevant situations, we calculate the criteria for spreading of such a layer in the corner of a capillary with polygonal cross-section. In a capillary with a cross-section in the shape of an isosceles triangle of varying corner size, these criteria are used to determine the unique capillary entry pressures for piston-like displacement from alternative solutions of the general equation. These solutions relate to displacements in the presence or absence of layers in the various differently sized corners.
Viscous fingering in porous media is an instability which occurs when a low-viscosity injected fl... more Viscous fingering in porous media is an instability which occurs when a low-viscosity injected fluid displaces a much more viscous resident fluid, under miscible or immiscible conditions. Immiscible viscous fingering is more complex and has been found to be difficult to simulate numerically and is the main focus of this paper. Many researchers have identified the source of the problem of simulating realistic immiscible fingering as being in the numerics of the process, and a large number of studies have appeared applying high-order numerical schemes to the problem with some limited success. We believe that this view is incorrect and that the solution to the problem of modelling immiscible viscous fingering lies in the physics and related mathematical formulation of the problem. At the heart of our approach is what we describe as the resolution of the “M-paradox”, where M is the mobility ratio, as explained below. In this paper, we present a new 4-stage approach to the modelling of r...
The formation and deposition of mineral scales, such as barium sulphate (BaSO4) and calcium carbo... more The formation and deposition of mineral scales, such as barium sulphate (BaSO4) and calcium carbonate (CaCO3), is a common problem in many industrial and life science processes. This is caused by chemical incompatibility due either to the mixing of incompatible aqueous solutions or due to changes of the physical conditions, usually temperature and pressure. Many laboratory studies have been conducted using techniques broadly classified into batch and flowing tests to understand the reaction and mechanisms which occur in the initial stages of scale formation and its subsequent deposition on a solid surface. In this study we focused on the dynamic (kinetic) deposition of barium sulphate arising from the mixing of two incompatible brines, one containing barium (Ba2+) ions and other containing sulphate (SO42−) ions, suitably charged balanced by other inert anions and cations. The mechanism of barium sulphate (barite) deposition is often assumed to be a one-step reaction in which the ion...
Microbial reservoir souring poses a significant threat to safe oil and gas production and operati... more Microbial reservoir souring poses a significant threat to safe oil and gas production and operations and it is difficult to control and mitigate. Predicting future H2S trends with reservoir souring models is done in an attempt to define the worst-case scenario and make critical decisions related to the asset field life. Unfortunately, these predictions often prove wrong because of the large uncertainties around parameters used within these models and because predicting the behaviour of living microorganisms is much more complex than dealing with most other chemical challenges in oil & gas. This work proposes an alternative data-driven and mechanistic approach to the investigation of the souring problem in Alba, a mature North Sea field water flooded since 1994. A comprehensive dataset including water chemistry analyses, gas composition trends, fluid rates etc. is used to find important correlations between produced fluid compositions and changes in H2S production. The concept of bio...
... The major requirement for pre-emptive squeezes into dry or low water cut wells relates to ...... more ... The major requirement for pre-emptive squeezes into dry or low water cut wells relates to ... 1000 PV) are seen for the aqueous system C1b, indication that longer field squeeze lifetime would ... 3. Collins, I R., Jordan, MM, and Taylor, SE, 2000, The Development and application of a ...
Viscous fingering in porous media occurs when the (miscible or immiscible) displacing fluid has a... more Viscous fingering in porous media occurs when the (miscible or immiscible) displacing fluid has a lower viscosity than the displaced fluid. For example, immiscible fingering is observed in experiments where water displaces a much more viscous oil. Modelling the observed fingering patterns in immiscible viscous fingering has proven to be very challenging, which has often been identified as being due to numerical issues. However, in a recent paper (Sorbie et al. in Transp. Porous Media 133:331–359, 2020) suggested that the modelling issues are more closely related to the physics and formulation of the problem. They proposed an approach based on the fractional flow curve, $${f}_{w}^{*}$$ f w ∗ , as the principal input, and then derived relative permeabilities which give the maximum total mobility. Sorbie et al. were then able to produce complex, well-resolves immiscible finger patterns using elementary numerical methods. In this paper, this new approach to modelling immiscible viscous ...
This document is also available on the Scottish Government website: www.scotland.gov.uk APS Group... more This document is also available on the Scottish Government website: www.scotland.gov.uk APS Group Scotland DPPAS33661 (07/14) w w w. s c o t l a n d. g o v. u k
The idea of injecting low salinity water into a petroleum reservoir is not novel and was often us... more The idea of injecting low salinity water into a petroleum reservoir is not novel and was often used in the 70's prior to the injection of surfactant. Yet, recently it was shown that simply injecting sufficiently low salinity water improves oil recovery (LoSal™). Many possible mechanisms concerning Low salinity waterflood have been proposed in the literature. This paper describes an experimental investigation into some of the factors controlling the increased oil recovery observed when low salinity brine is injected into oil saturated reservoir core samples. Extensive chemical analyses were performed on the effluent showing the extent of interaction between the injected brine, the oil and the rock matrix.
A large, untapped EOR potential may be extracted by extending polymer flooding to carbonate reser... more A large, untapped EOR potential may be extracted by extending polymer flooding to carbonate reservoirs. However, several challenges are encountered in carbonates due to generally more heterogeneous rock and lower permeability. In addition, high salinity may lead to high polymer retention. Here we show how in-situ viscosity varies with permeability and heterogeneity in carbonate rock from analysis of core flood results and combined with review of data available in literature. In-situ rheology experiments were performed on both carbonate outcrop and reservoir cores with a range in permeabilities. The polymer used was a high ATBS content polyacrylamide (SAV10) which tolerates high temperature and high salinity. Some cores were aged with crude oil to generate non-water-wet, reservoir representative wettability conditions. These results are compared to a compilation of literature data on in-situ rheology for predominantly synthetic polymers in various carbonate rock. A systematic approac...
Bulletin of Chemical Reaction Engineering & Catalysis
Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP)... more Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP) floods and this silicate scale deposition affects oil production. Hence, it is important to examine the conditions that lead to silicate scale forming. The severity of the silicate scaling reaction, the type and morphology of silica/silicate scale formed in an experimental ASP flood were studied for pH values 5, 8.5, and 11, whilst the temperature was kept constant at 90 ℃. In addition, the impact of calcium ion was studied and spectroscopic analyses were used to identify the extent of scaling reaction, morphology type and the functional group present in the precipitates. This was performed using imagery of the generated precipitates. It was observed that the silica/silicate scale is most severe at the highest pH and Ca:Mg molar ratios examined. Magnesium hydroxide and calcium hydroxide were observed to precipitate along with the silica and Mg-silicate/Ca-silicate scale at pH 11. The pr...
Scale inhibition efficiency is determined in bulk jar tests in order to determine a minimum inhib... more Scale inhibition efficiency is determined in bulk jar tests in order to determine a minimum inhibitor concentration (MIC) which gives some acceptable level of inhibition (say 95%). However, this test refers principally to the bulk precipitation of barium mineral scale from solution, rather than its deposition on a surface. The complementary tube blocking test gives some insight into scale adhesion at a surface, but this is a very short residence time test. An experimental study has been conducted to examine the interactions between surface and bulk BaSO4 scaling processes in uninhibited and inhibited supersaturated brines. In this study, precipitation both in bulk and onto a Hastelloy metal surface has been studied in longer term bulk jar tests at various temperatures. It has been demonstrated that the use of PPCA at concentrations beneath the MIC level, as determined by bulk jar tests, can promote surface scaling. This comes about as a result of complex interactions between bulk pr...
In the application of chemical inhibitors in field squeeze treatments for the prevention of sulph... more In the application of chemical inhibitors in field squeeze treatments for the prevention of sulphate and carbonate mineral scale formation, it is very important that the chemical species involved can be accurately assayed. When the inhibitor concentration drops below a predetermined threshold level for scale inhibition (Ct) then the well may need to be resqueezed. The accurate assay of scale inhibitors down to concentration levels of a few ppm in real field brines can be a difficult task. In this paper, we examine a number of interferences which often make assay techniques very difficult to apply in field produced brines. The inhibitors examined in this work include phosphonates (PH), polyacrylates (PAA) and phosphino-polycarboxylates (PPCA). The main objective of this work is to develop suitable pre-treatment/purification techniques which allow the standard wet chemical techniques to be applied effectively after appropriate modification. Successful techniques - all based on careful...
Summary Using chemical scale inhibitors is one of the most common methods of preventing downhole ... more Summary Using chemical scale inhibitors is one of the most common methods of preventing downhole and topside mineral scale formation in oil fields. Several aspects of the brine composition may affect the performance of the various scale inhibitors. In this paper, we focus on the roles of calcium and magnesium ion concentrations. The calcium concentration in a particular reservoir and in the inhibitor slug often determines the extent to which the inhibitor species is retained in the near-wellbore area (i.e., on its adsorption or precipitation behavior). What is less well understood is the effect of divalent cations on the inhibition process itself. Common ion effects are well known; however, for pentaphosphonate inhibitor species (e.g., DETPMP), significant improvements in inhibition efficiency have been reported by increasing the calcium concentration in the solution. In this paper, we expand significantly on such observations. The effect of calcium and magnesium cation concentratio...
This study investigates the interaction of compositional effects with the flow behaviour during n... more This study investigates the interaction of compositional effects with the flow behaviour during near-miscible (and immiscible) CO 2-oil displacements in heterogeneous systems. A series of numerical simulations modelling 1D slim-tube and 2D areal systems were simulated using a fully compositional simulator. A number of grid resolutions for a slimtube model were simulated to choose the proper level of numerical dispersion to mimic the actual physical dispersion. The corresponding 2D cases are based on a small heterogeneous sector model of dimensions 50 m × 10 m, in order that the fine-scale displacement physics can be modelled accurately. We investigated various flow regimes ranging from viscous fingering to channelling displacements within heterogeneous random correlated fields. We found that the reduced recovery is the result of a combination of differences in sweep efficiency associated with the viscous fingering and possible differences in local mixing that affect composition path. At the same time, the unstable phase flow determined by the underlying heterogeneity slows the flow in the unswept area and leads to unequal displacement performance between preferential and non-preferential routes. Specifically, lighter components have moved preferentially in high gas saturation zones, and leaving the heavier components behind in slower flow zones. In the case of channelling flow, compositional effects were less important since the permeability channel dominated the displacement. Both the ultimate oil recovery and component recovery are significantly and about equally reduced, when the underlying heterogeneity is of dominant influence. To summarise, compositional effects can have a very significant impact on the prediction of near-miscible CO 2 EOR projects. Issues such as front stability, local displacement efficiency and formation of fingering/channelling during CO 2 near-miscible displacement can lead to behaviour that is significantly different from immiscible flooding in these systems. The process of mass transfer between CO 2 and oil can be hampered to a certain degree by unstable flow depending on the level of heterogeneity. This leads to a further reduction in component recovery, particularly of the heavier components. The complete dataset and results of this study are available online as a model case example for compositional flows in heterogeneous systems (Wang et al. in "The analysis of compositional effects on global flow regimes in CO 2 nearmiscible displacements in heterogeneous systems" dataset for paper SPE
Pore networks can be extracted from 3D rock images to accurately predict multiphase flow properti... more Pore networks can be extracted from 3D rock images to accurately predict multiphase flow properties of rocks by network flow simulation. However, the predicted flow properties may be sensitive to the extracted pore network if it is small, even though its underlying characteristics are representative. Therefore, it is a challenge to investigate the effects on flow properties of microscopic rock features individually and collectively based on small samples. In this article, a new approach is introduced to generate from an initial network a stochastic network of arbitrary size that has the same flow properties as the parent network. Firstly, we characterise the realistic parent network in terms of distributions of the geometrical pore properties and correlations between these properties, as well as the connectivity function describing the detailed network topology. Secondly, to create a stochastic network of arbitrary size, we generate the required number of nodes and bonds with the correlated properties of the original network. The nodes are randomly located in the given network domain and connected by bonds according to the strongest correlation between node and bond properties, while honouring the connectivity function. Thirdly, using a state-of-the-art two-phase flow network model, we demonstrate for two samples that the rock flow properties (capillary pressure, absolute and relative permeability) are preserved in the stochastic networks, in particular, if the latter are larger than the original, or the method reveals that the size of the original sample is not representative. We also show the information that is necessary to reproduce the realistic networks correctly, in particular the connectivity function. This approach forms the basis for the stochastic generation of networks from multiple rock images at different resolutions by combining the relevant statistics from the corresponding networks, which will be presented in a future publication.
The oil industry is currently facing severe restrictions concerning the discharge of oilfield che... more The oil industry is currently facing severe restrictions concerning the discharge of oilfield chemicals into the environment. The purpose of this study is to test the possibility of replacing an organic phosphonate scale inhibitor (DETPMP) by a more environmentally friendly “green” species: carboxymethyl inulin (CMI). Although, promising these results are nevertheless far inferior to the performance exhibited by the DETPMP
In a cylindrical pore of arbitrary wettability, we analyse the existence of a three-fluid contact... more In a cylindrical pore of arbitrary wettability, we analyse the existence of a three-fluid contact line connecting the fluid-fluid interfaces between two bulk phases and the third phase contained in a cusp near the pore wall. This analysis is supported by the very similar, but simpler, analysis for a constriction between parallel plates. From the force balance at the contact line and the equations for the interface curvatures we derive expressions for the cusp height and for the capillary entry pressure related to piston-like displacement between the two bulk phases. The latter is independent of the existence of a cusp and its phase pressure. Based on some realistic assumptions, of which the most important is that a cusp grows continuously from the onset when its phase pressure is increased, we analyse under which conditions a cusp can exist, and, when it exists, what its behaviour is as a function of the cusp phase pressure. We find a simple criterion involving (two ratios of) the three interfacial tensions and two of the three contact angles, which determines whether the three-fluid contact line and, consequently, a cusp exists. The range of contact angles, as well as the size of the cusp increases, when the cusp phase is close to spreading. Not only cusps of the wetting phase can occur, but also of the intermediate-wetting phase. Numerical examples are presented to illustrate the range of behaviour of the cusps.
In this work we derive rigorously the free energy balance for three fluid phases in a straight ca... more In this work we derive rigorously the free energy balance for three fluid phases in a straight capillary of arbitrarily shaped cross-section. This balance is then used to derive the general equation for the capillary entry pressures of all possible two-phase and three-phase displacements. Moreover, the equation provides the criterion determining the existence of layers of the intermediate-wetting phase separating the wetting and non-wetting phases in the corners or cavities of a capillary, by also treating the spreading of such layers as a capillary displacement. For a number of combinations of interfacial tensions and contact angles, illustrating all the different relevant situations, we calculate the criteria for spreading of such a layer in the corner of a capillary with polygonal cross-section. In a capillary with a cross-section in the shape of an isosceles triangle of varying corner size, these criteria are used to determine the unique capillary entry pressures for piston-like displacement from alternative solutions of the general equation. These solutions relate to displacements in the presence or absence of layers in the various differently sized corners.
Viscous fingering in porous media is an instability which occurs when a low-viscosity injected fl... more Viscous fingering in porous media is an instability which occurs when a low-viscosity injected fluid displaces a much more viscous resident fluid, under miscible or immiscible conditions. Immiscible viscous fingering is more complex and has been found to be difficult to simulate numerically and is the main focus of this paper. Many researchers have identified the source of the problem of simulating realistic immiscible fingering as being in the numerics of the process, and a large number of studies have appeared applying high-order numerical schemes to the problem with some limited success. We believe that this view is incorrect and that the solution to the problem of modelling immiscible viscous fingering lies in the physics and related mathematical formulation of the problem. At the heart of our approach is what we describe as the resolution of the “M-paradox”, where M is the mobility ratio, as explained below. In this paper, we present a new 4-stage approach to the modelling of r...
The formation and deposition of mineral scales, such as barium sulphate (BaSO4) and calcium carbo... more The formation and deposition of mineral scales, such as barium sulphate (BaSO4) and calcium carbonate (CaCO3), is a common problem in many industrial and life science processes. This is caused by chemical incompatibility due either to the mixing of incompatible aqueous solutions or due to changes of the physical conditions, usually temperature and pressure. Many laboratory studies have been conducted using techniques broadly classified into batch and flowing tests to understand the reaction and mechanisms which occur in the initial stages of scale formation and its subsequent deposition on a solid surface. In this study we focused on the dynamic (kinetic) deposition of barium sulphate arising from the mixing of two incompatible brines, one containing barium (Ba2+) ions and other containing sulphate (SO42−) ions, suitably charged balanced by other inert anions and cations. The mechanism of barium sulphate (barite) deposition is often assumed to be a one-step reaction in which the ion...
Microbial reservoir souring poses a significant threat to safe oil and gas production and operati... more Microbial reservoir souring poses a significant threat to safe oil and gas production and operations and it is difficult to control and mitigate. Predicting future H2S trends with reservoir souring models is done in an attempt to define the worst-case scenario and make critical decisions related to the asset field life. Unfortunately, these predictions often prove wrong because of the large uncertainties around parameters used within these models and because predicting the behaviour of living microorganisms is much more complex than dealing with most other chemical challenges in oil & gas. This work proposes an alternative data-driven and mechanistic approach to the investigation of the souring problem in Alba, a mature North Sea field water flooded since 1994. A comprehensive dataset including water chemistry analyses, gas composition trends, fluid rates etc. is used to find important correlations between produced fluid compositions and changes in H2S production. The concept of bio...
... The major requirement for pre-emptive squeezes into dry or low water cut wells relates to ...... more ... The major requirement for pre-emptive squeezes into dry or low water cut wells relates to ... 1000 PV) are seen for the aqueous system C1b, indication that longer field squeeze lifetime would ... 3. Collins, I R., Jordan, MM, and Taylor, SE, 2000, The Development and application of a ...
Viscous fingering in porous media occurs when the (miscible or immiscible) displacing fluid has a... more Viscous fingering in porous media occurs when the (miscible or immiscible) displacing fluid has a lower viscosity than the displaced fluid. For example, immiscible fingering is observed in experiments where water displaces a much more viscous oil. Modelling the observed fingering patterns in immiscible viscous fingering has proven to be very challenging, which has often been identified as being due to numerical issues. However, in a recent paper (Sorbie et al. in Transp. Porous Media 133:331–359, 2020) suggested that the modelling issues are more closely related to the physics and formulation of the problem. They proposed an approach based on the fractional flow curve, $${f}_{w}^{*}$$ f w ∗ , as the principal input, and then derived relative permeabilities which give the maximum total mobility. Sorbie et al. were then able to produce complex, well-resolves immiscible finger patterns using elementary numerical methods. In this paper, this new approach to modelling immiscible viscous ...
This document is also available on the Scottish Government website: www.scotland.gov.uk APS Group... more This document is also available on the Scottish Government website: www.scotland.gov.uk APS Group Scotland DPPAS33661 (07/14) w w w. s c o t l a n d. g o v. u k
The idea of injecting low salinity water into a petroleum reservoir is not novel and was often us... more The idea of injecting low salinity water into a petroleum reservoir is not novel and was often used in the 70's prior to the injection of surfactant. Yet, recently it was shown that simply injecting sufficiently low salinity water improves oil recovery (LoSal™). Many possible mechanisms concerning Low salinity waterflood have been proposed in the literature. This paper describes an experimental investigation into some of the factors controlling the increased oil recovery observed when low salinity brine is injected into oil saturated reservoir core samples. Extensive chemical analyses were performed on the effluent showing the extent of interaction between the injected brine, the oil and the rock matrix.
A large, untapped EOR potential may be extracted by extending polymer flooding to carbonate reser... more A large, untapped EOR potential may be extracted by extending polymer flooding to carbonate reservoirs. However, several challenges are encountered in carbonates due to generally more heterogeneous rock and lower permeability. In addition, high salinity may lead to high polymer retention. Here we show how in-situ viscosity varies with permeability and heterogeneity in carbonate rock from analysis of core flood results and combined with review of data available in literature. In-situ rheology experiments were performed on both carbonate outcrop and reservoir cores with a range in permeabilities. The polymer used was a high ATBS content polyacrylamide (SAV10) which tolerates high temperature and high salinity. Some cores were aged with crude oil to generate non-water-wet, reservoir representative wettability conditions. These results are compared to a compilation of literature data on in-situ rheology for predominantly synthetic polymers in various carbonate rock. A systematic approac...
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Papers by Kenneth Sorbie