Systematic Modelling of Unstable Displacement

2021 ◽  
Author(s):  
Arne Skauge ◽  
Kenneth Stuart Sorbie ◽  
Iselin Cecilie Salmo ◽  
Tormod Skauge
Keyword(s):  
Single Point ◽  
Viscous Fingering ◽  
Mobility Ratio ◽  
Fluid Viscosity ◽  
Fractional Flow ◽  
Fine Grid ◽  
Rock Heterogeneity ◽  
Unstable Displacement ◽  
The Impact ◽  
Adverse Mobility Ratio

Abstract Modelling unstable displacement is a challenge which may lead to large errors in reservoir simulations. Field scale coarse grid simulations therefore need to be anchored to more reliable fine grid models which capture fluid displacement instabilities in a physically correct manner. In this paper, a recently developed approach for accurately modelling viscous fingering has been applied to various types of unstable displacement. The method involves estimation of dispersivity of the porous medium and length scale of the model to determine the required size of the simulation grid cell. Fractional flow theory is then applied to obtain the correct saturation of the injected phase in the unstable fingers formed due to the adverse mobility ratio. Unstable displacement experiments have been history matched using 2D-imaging of in-situ saturation as a calibration of our method, before carrying out sensitivity calculations on the effect of fluid viscosity, and rock heterogeneity. Our modelling approach allows us to carry out simulations using a conventional numerical simulator using elementary numerical methods (e.g. single-point upstreaming). The methods used to model instability (Sorbie et al, 2020) was originally developed for immiscible water/oil systems. The current paper now presents new results applying this approach to unstable gas displacements, where adverse viscosity ratios may be even higher than in water/oil systems. The displacement with injected gas is shown to be influenced by mass exchanges between the gas and oil as the alternating fluids (water and gas) are injected in WAG processes. Swelling of fingers delay the gas front and WAG processes divert the injected gas and improve sweep efficiency. We have also modelled water-oil displacement at adverse mobility and shown the benefit which is obtained by reducing the instability by adding polymers to viscosify the injected water. The impact of rock heterogeneity has different effect depending on buoyancy forces and the degree of crossflow into the high permeable zones. This paper extends our novel approach to modelling the fine scale distribution of the injected fluids in adverse mobility ratio displacements. This approach has now been applied to both, gas/oil and water/oil systems where viscous fingering is present, either at extremely adverse mobility ratios and/or for reservoirs where the permeability field is very heterogeneous.

A Finite-Element Method for Reservoir Simulation

1981 ◽  
Vol 21 (01) ◽  
pp. 115-128 ◽  
Author(s):  
Larry C. Young
Keyword(s):  
Finite Element ◽  
Finite Element Methods ◽  
Reservoir Simulation ◽  
Finite Differences ◽  
Time Derivative ◽  
Mobility Ratio ◽  
Difference Approximation ◽  
Central Difference ◽  
Fine Grid ◽  
Adverse Mobility Ratio

Abstract Several previous studies have applied finite-element methods to reservoir simulation problems. Accurate solutions have been demonstrated with these methods; however, competitiveness with finite difference has not been established for most nonlinear reservoir simulation problems. In this study a more efficient finite-element procedures is presented and tested. The method is Galerkin-based, and improved efficiency is obtained by combining Lagrange trial functions with Lobatto quadrature in a particular way. The simulation of tracer performance, ion exchange preflush performance, and adverse mobility ratio miscible displacements is considered. For the problems considered, the method is shown to yield accurate solutions with less computing expense than finite differences or previously proposed finite-element techniques. For the special case of linear trial functions, the method reduces to a five-point central difference approximation. In contrast to previously reported results, this approximation is found to simulate adverse mobility ratio displacements without grid orientation sensitivity, provided a sufficiently fine grid is used. Introduction In the past few years several studies have investigated the use of finite-element methods in reservoir simulation. These include single-phase two-component simulations in one1–3 and two4,5 spatial dimensions and two-phase immiscible calculations in both one6–8 and two9,10 dimensions. These studies have demonstrated that the method is capable of giving accurate solutions, particularly for small slug problems and adverse mobility ratio displacements. All these studies used what we term conventional Galerkin finite-element techniques,1 and, unfortunately, these methods have not proved to be cost competitive with finite differences for most nonlinear reservoir simulation problems. A reduction in computing requirements is, therefore, necessary to make finite-element methods truly useful for reservoir simulation. Relative to finite differences, the increased computing requirements of conventional Galerkin-based methods are due to the following.The approximation of time-derivative terms involves the same number of surrounding grid points as the approximation of flow terms; thus, implicit-pressure/explicit-saturation (IMPES) techniques are not possible (see Ref. 12, Chap. 7).The matrices which result from the approximation of flow terms are not nearly so sparse as in finite differences; thus, the solution of matrix problems requires more computation.The computational work required to generate matrix coefficients is considerably greater than with finite differences due to the number of numerical integrations which must be performed.

A Unified Theory for Stable and Unstable Miscible Displacement

1963 ◽  
Vol 3 (03) ◽  
pp. 205-213 ◽  
Author(s):  
R.L. Perrine
Keyword(s):  
Porous Medium ◽  
Turbulent Flow ◽  
Darcy’S Law ◽  
Flow Behavior ◽  
Viscous Fingering ◽  
Darcy's Law ◽  
Miscible Displacement ◽  
Fluid Viscosity ◽  
Flow Conditions ◽  
Unstable Displacement

Introduction Many experimental studies of miscible displacement in porous media have been conducted with prediction of reservoir displacement efficiency as the ultimate objective. Most such studies have utilized lower displacing than displaced fluid viscosity, scaled to potential reservoir fluid pairs. Theoretical approaches have been largely limited to unit viscosity ratios, however, in spite of the necessity for an understanding of the mechanism of the unstable, adverse viscosity ratio displacement process. An obvious reason is the difficulty of describing in mathematical form the viscous fingering characteristic of these conditions. Observation of experiments conducted with dyed fluids in transparent systems suggests an analogy between unstable miscible displacement and turbulent flow in a pipe. In both cases there are fluctuations around a simpler, mean flow behavior. An important difference is that flow behavior of interest in the porous medium is entirely transient, contained within a transition zone between displacing and displaced fluids. Transient behavior complicates description in that coefficients in the equations become variables rather than constants. In the study reported here, the analogy with turbulent flow has been used in creating unstable miscible displacement as a quasi-turbulent displacement process. The purpose has been to derive, even if restricted to an idealized conceptual model, a unified theoretical relationship applicable to both stable and unstable displacement. A relationship meeting these specifications up to moderately adverse viscosity ratios, such as 17:1, is presented. One fluctuation parameter in the theory and dispersion coefficients are obtained by empirical means. The idealized theory is compared with experimental results. UNSTABLE MISCIBLE DISPLACEMENT AS QUASI-TURBULENT DARCY FLOW The miscible displacement of one fluid by another within a porous medium is considered in this study. Flow conditions are such that Darcy's law is applicable. It is further assumed that, by the stability criterion proposed by Perrine, initial flow conditions lie well within the regime of instability. Thus substantial viscous fingering is assured.We wish to show how this flow regime can be represented as quasi-turbulent. That is, the Reynolds number for the established flow conditions is below that for inertial or turbulent flow within a porous medium, and lies within the regime for which Darcy's law is valid. Yet flow behavior can be described as the combination of some relatively simple average result, and characteristic fluctuations that are superimposed on the simpler behavior. Stated another way, flow behavior includes the movement of layers of fluids with different velocities past or over one another. Such descriptions are characteristic of turbulent pipe flow. The fluctuations in the present case are a direct consequence of the local viscous fingering which accompanies the unstable displacement process. Should displacement become stable, fluctuations would die out. It is of particular importance to note that fluctuations such as these can interact in a way that contributes to material transport by the basic flow. The basic transport equations required for engineering calculations must be modified to reflect this fact. SPEJ P. 205^

scholarly journals A New Dynamic Model for Sealed Coring Saturation Correction in Hydrocarbon Reservoir

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Bin Tu ◽  
Jie Li
Keyword(s):  
Mathematical Model ◽  
Water Saturation ◽  
Correction Method ◽  
Fluid Viscosity ◽  
Dissolved Gas ◽  
Fractional Flow ◽  
Model Correction ◽  
Advantages And Disadvantages ◽  
Hydrocarbon Reservoir ◽  
The Impact

It is one of the most intuitive methods to analyze the formation of oil and water saturation by sealed coring. But this method is affected by a variety of factors, such as pore volume change, fluid compression, and separation of dissolved gas. In view of the impact of such factors on sealed coring test saturation, there are four kinds of correlation methods currently, namely, comprehensive coefficient correction method, experiment correlation method, mathematical statistics method, and mathematical model correction method, with their own advantages and disadvantages. Based on the analysis of physical change during core lifting process, this paper proposes the mathematical model for dynamic correction of core saturation based on dissolved gas drive filtration theory, multiphase flow fractional flow theory, and corresponding work flow. This method comprehensively considers the impact of relative permeability of three-phase fluid flow, elastic compression nature of fluid and rock, fluid viscosity, volume factor, solution GOR, and other high-pressure PVTs, so it features a wider adaptability, and the accuracy of model correction results satisfies the project requirements. This method provides a reliable basis for the true oil-water saturation of actual reservoir and has an important theoretical and practical significance.

scholarly journals Analysis of the impacts of relative permeability and mobility ratio on heterogeneity loss error during upscaling of geological models

2020 ◽  
Vol 75 ◽  
pp. 53
Author(s):  
Ameneh Darban ◽  
Mojtaba Ghaedi ◽  
Jafar Qajar
Keyword(s):  
Relative Permeability ◽  
Influential Factors ◽  
Mobility Ratio ◽  
Numerical Dispersion ◽  
Optimum Level ◽  
Fine Grid ◽  
Flow Equations ◽  
Light Oil ◽  
Performance Error ◽  
The Impact

The detailed geological fine grids are upscaled to create reliably sized simulation coarse models to solve flow equations in a more efficient way. Any upscaling process results in a loss of accuracy, along with an increase of errors. Numerical dispersion, heterogeneity loss, and connectivity misrepresentation are responsible for the upscaling errors. Recognizing the source of each error, and the behavior of influential factors through upscaling process could provide an optimum level of upscaling and an evaluation of upscaling methods’ accuracy. Despite the importance of upscaling error, little attention has been paid to this subject. This paper represents a rigorous analysis of the heterogeneity loss behavior associated with the relative permeability contrast and the mobility ratio under a waterflooding process. For this purpose, heterogeneous fine grid models are constructed by the fractional Brownian motion process. The models are upscaled by three upscaling factors. The models achieved are implemented to eliminate the impact of numerical error among upscaling errors in order to focus strictly on heterogeneity loss. Water–oil displacement simulation is then performed on fine and corresponding refined upscaled models at three different ratios of relative permeabilities and mobility ratios. In the next stage, the relation between flow performance error and heterogeneity loss is investigated by the heterogeneity loss plot. The slope of this plot provides the reservoir engineer an insight to evaluate the performance of upscaling methods and the behavior of the influential factors on upscaling errors. Moreover, by using the heterogeneity loss plot for each ratio, a limit of coarsening is presented. Based on the results, the heterogeneity loss error is affected more by the mobility ratio contrast than the relative permeability difference. Also, it is demonstrated that water-wet reservoirs with light oil are more sensitive to the level of upscaling.

scholarly journals OP0277-PARE METABERN, THE EUROPEAN REFERENCE NETWORK FOR RARE HEREDITARY DISEASES: STRUCTURE, OBJECTIVES, METABOLIC RMDS AND THE ROLES OF EUROPEAN PATIENT ADVOCACY GROUPS (EPAGS)

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 168.2-168
Author(s):  
L. Wagner ◽  
S. Sestini ◽  
C. Brown ◽  
A. Finglas ◽  
R. Francisco ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Health Care ◽  
Social Science ◽  
Metabolic Pathways ◽  
Metabolic Disorders ◽  
Clinical Care ◽  
Single Point ◽  
Link Type ◽  
The Impact

Background:Inborn metabolic disorders (IMDs) currently encompass more than 1,500 diseases with new ones still to be identified1. Each of them is characterised by a genetic defect affecting a metabolic pathway. Only few of them have curative treatments, that target the respective metabolic pathway. Commonly, treatment examples include diet, substrate reduction therapies, enzyme replacement therapies, gene therapy and biologicals, enabling IMD-patient now to survive to adulthood. About 30 % of all IMDs involve the musculoskeletal system and are here referred to as rare metabolic RMDs. Generally, IMDs are very heterogenous with respect to symptoms and severity, often being systemic and affecting more children than adults. Thus, challenges include certified advanced training of adult metabolic experts, standardised transition plans, social support and development of therapies for diseases that do not have any cure yet.Objectives:Introduction of MetabERN, its structure and objectives, highlighting on the unique features and challenges of metabolic RMDs and describing the involvement of patient representation in MetabERN.Methods:MetabERN is stratified in 7 subnetworks (SNW) according to the respective metabolic pathways and 9 work packages (WP), including administration, dissemination, guidelines, virtual counselling framework, research/clinical trials, continuity of care, education and patient involvement. The patient board involves a steering committee and single point of contacts for each subnetwork and work package, respectively2. Projects include identifying the need of implementing social science to assess the psycho-socio-economic burden of IMDs, webinars on IMDs and their transition as well as surveys on the impact of COVID-193 on IMD-patients and health care providers (HCPs), social assistance for IMD-patients and analysing the transition landscape within Europe.Results:The MetabERN structure enables bundling of expertise, capacity building and knowledge transfer for faster diagnosis and better health care. Rare metabolic RMDs are present in all SNWs that require unique treatments according to their metabolic pathways. Implementation of social science to assess the psycho-socio-economic burden of IMDs is still underused. Involvement of patient representatives is essential for a holistic healthcare not only focusing on clinical care, but also on the quality of life for IMD-patients. Surveys identified unmet needs of patient care, patients having little information on national support systems and structural deficits of healthcare systems to ensure HCP can provide adequate clinical care during transition phases. These results are collected by MetabERN and forwarded to the Directorate-General for Health and Food Safety (DG SANTE) of the European Commission (EC) to be addressed further.Conclusion:MetabERN offers an infrastructure of virtual healthcare for patients with IMDs. Thus, in collaboration with ERN ReCONNET, MetabERN can assist in identifying rare metabolic disorders of RMDs to shorten the odyssey of diagnosis and advise on their respective therapies. On the other hand, MetabERN can benefit from EULAR’s longstanding experience regarding issues affecting the quality of life, all RMD patients are facing, such as pain, stiffness, fatigue, rehabilitation, maintaining work and disability claims.References:[1]IEMbase - Inborn Errors of Metabolism Knowledgebase http://www.iembase.org/ (accessed Jan 29, 2021).[2]MetabERN: European Refence Network for Hereditary Metabolic Disorders https://metab.ern-net.eu/ (accessed Jan 29, 2021).[3]Lampe, C.; Dionisi-Vici, C.; Bellettato, C. M.; Paneghetti, L.; van Lingen, C.; Bond, S.; Brown, C.; Finglas, A.; Francisco, R.; Sestini, S.; Heard, J. M.; Scarpa, M.; MetabERN collaboration group. The Impact of COVID-19 on Rare Metabolic Patients and Healthcare Providers: Results from Two MetabERN Surveys. Orphanet J. Rare Dis.2020, 15 (1), 341. https://doi.org/10.1186/s13023-020-01619-x.Acknowledgements:The authors thank the MetabERN collaboration group, the single point of contacts (SPOC) of the MetabERN patient board and the Transition Project Working Group (TPWG)Disclosure of Interests:None declared

A Novel Design of Landing Gear Oleo Strut Damper Using MR Fluid for Aircraft and UAV’s

2012 ◽  
Vol 225 ◽  
pp. 275-280
Author(s):  
Chandra B. Asthana ◽  
Rama B. Bhat
Keyword(s):  
Shock Absorber ◽  
Fluid Viscosity ◽  
Simulation Approach ◽  
Body Frame ◽  
Mr Fluid ◽  
Orifice Area ◽  
Aerial Vehicle ◽  
Impact Kinetic Energy ◽  
The Impact ◽  
Novel Design

Most landing gears used in aircraft employ very efficient oleo-pneumatic dampers to absorb and dissipate the impact kinetic energy of the aircraft body frame. A single-acting shock absorber is most commonly used in the oleo strut that has a metering pin extending through the orifice, which can vary the orifice area upon compression and extension of the strut. This variation is adjusted by shaping the metering pin so that the strut load is fairly constant under dynamic loading. In this paper, it is proposed to further change the damping coefficient as a function of time in order to achieve a semi-active control of the aircraft vibrations during landing by using Magnetorheological (MR) fluid in the Oleo. With the metering pin designed for a nominal flight condition, further variation in the fluid viscosity would help achieve the optimal performance in off-nominal flight conditions. A simulation approach is employed to show the effect of different profiles for viscosity variation in the MR fluid. The utility of such a damper can be very well exploited to include different criteria such as the landing distance after touchdown. This type of system can be used also in Unmanned Aerial Vehicle (UAV) application where the focus of design may be to accomplish the task without the consideration of passenger comfort.

The effects of corporate brand symbolism on consumer satisfaction and loyalty

2016 ◽  
Vol 28 (3) ◽  
pp. 481-498 ◽  
Author(s):  
Tatiana Anisimova
Keyword(s):  
Social Life ◽  
Consumer Satisfaction ◽  
Single Point ◽  
Social Aspects ◽  
Consumer Loyalty ◽  
Cross Sectional ◽  
Corporate Brand ◽  
Content Type ◽  
Strategic Role ◽  
The Impact

Purpose – The purpose of this paper is to test the effects of corporate brand symbolism on consumer satisfaction and loyalty on a sample of Australian automobile consumers. Design/methodology/approach – Survey research was employed to test the study hypotheses. The regression analysis was used to evaluate the relationships between an independent variable (corporate brand symbolism) and dependent variables (consumer satisfaction and loyalty). Findings – Support was found for all hypotheses formulated in this study. Regression results reveal consistent favourable and significant effects of corporate brand symbolism on both consumer satisfaction and loyalty. Research limitations/implications – Although this paper makes contributions in international marketing, the cross-sectional nature of the data collection method limits the information gained to the single point in time. This research studied the impact of corporate brand symbolism on consumers of one original equipment manufacturers (OEM). Having a larger number of participating car manufacturers/OEMs would have provided a wider insight. However, time and resources limitation did not allow to study a larger sample. In the future, practitioners are recommended to further understand the relationship between self and social aspects of brand symbolism in order to formulate more targeted communication strategies. Practical implications – The findings of this study point to the strategic role of the brand in generating both satisfaction and loyalty. In the light of increasing advertising costs and decreasing consumer loyalty, strengthening corporate brand symbolism makes a lot of economic sense. The findings suggest that managers need to take into account consumer need for identity expression and consider this in their branding strategies. Social implications – Humans are social beings by nature. However, international brand research has paid relatively little attention to how products are used by consumers in everyday life, including their social life. Consumer behaviours increasingly depend on social meanings they imbue brands with beyond products’ functional utility. It is argued the focus of symbolic consumption needs to be broadened and integrated more with social science concepts. Originality/value – This study captures a construct of corporate brand symbolism by including self and social aspects of symbolism. The current study also comprehensively measures consumer loyalty, including cognitive, affective and behavioural types of loyalty.

A Novel Gemini Cationic Viscoelastic Surfactant-Based Fluid for High Temperature Well Stimulation Applications

2021 ◽  
Author(s):  
Dawn Friesen ◽  
Brian Seymour ◽  
Aaron Sanders
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Chain Length ◽  
Surfactant Concentration ◽  
Gemini Surfactant ◽  
Alkyl Chain ◽  
Friction Reduction ◽  
Fluid Viscosity ◽  
Viscoelastic Surfactant ◽  
The Impact

Abstract Viscoelastic surfactant (VES)-based fracturing fluids can reduce the risk of formation damage when compared with conventional polymer-based fracturing systems. However, many VES systems lose viscoelasticity rapidly under high-temperature conditions, leading to high fluid leakoff and problems in proppant placement. A gemini cationic VES-based system offering thermal stability above 250°F and its efficiency in friction reduction is presented in this paper. Rheology measurements were conducted on viscoelastic cationic gemini surfactant fluids as a function of temperature (70 – 300°F) and surfactant concentration. The length of surfactant alkyl chain was varied to investigate the impact of surfactant chain length on VES fluid viscosity at elevated temperatures. The effect of flow rate on friction reduction capability of the surfactant fluid was measured on a friction flow loop. Foam rheology measurements were conducted to evaluate the VES fluid's ability to maintain high temperature viscosity with reduced surfactant concentration. A gemini cationic surfactant was used to prepare a viscoelastic surfactant system that could maintain viscosity over 50 cP at a shear rate of 100 s−1up to at least 250°F. With this system, viscoelastic gel viscosity was maintained without degradation for over 18 hours at 250°F, and the fluid showed rapid shear recovery throughout. Decreasing the average alkyl chain length on the surfactant reduced the maximum working temperature of the resulting viscoelastic gel and showed the critical influence of surfactant structure on the resulting fluid performance. The presence of elongated, worm-like micelles in the fluid provided polymer-like friction reduction even at low surfactant concentrations, with friction reduction of over 70% observed during pumping (relative to fresh water) up to a critical Reynolds number. Energized fluids could also be formulated with the gemini surfactant to give foam fluids suitable for hydraulic fracturing or wellbore cleanouts. The resulting viscoelastic surfactant foams had viscosities over 50 cP up to at least 300°F with both nitrogen and carbon dioxide as the gas phase. The information presented in this paper is important for various field applications where thermal stability of the treatment fluid is essential. This will hopefully expand the use of VES-based systems as an alternative to conventional polymer systems in oilfield applications where a less damaging viscosified fluid system is required.

Resolving the Unique Invariant Slip-Direction in Rigid Three-Dimensional Multi-Point Impacts at Stick-Slip Transitions

2018 ◽  
Author(s):  
Abhishek Chatterjee ◽  
Alan Bowling
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Impact Behavior ◽  
Slip Direction ◽  
Stick Slip ◽  
Impact Forces ◽  
Post Impact ◽  
Impact Problems ◽  
Slip Transition ◽  
The Impact

This work presents a new approach for resolving the unique invariant slip direction at Stick-Slip Transition during impact. The solution method presented in this work is applicable to both single-point and multi-point impact problems. The proposed method utilizes rigid body constraints to resolve the impact forces at all collision points in terms of a single independent impact forces parameter. This work also uses an energetic coefficient of restitution to terminate impact events, thereby yielding energetically consistent post-impact behavior.

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