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ECMOR XVI - 16th European Conference on the Mathematics of Oil Recovery
- Conference date: September 3-6, 2018
- Location: Barcelona, Spain
- Published: 03 September 2018
41 - 60 of 172 results
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Higher Resolution Hybrid And Vt Finite-Volume Formulations For 3-Component 2-Phase Flow On Unstructured Grids
Authors Y. Xie and M.G. EdwardsSummaryNovel fractional-step higher resolution hybrid cell-centred finite-volume formulations are presented for twophase and three component two-phase flow with gravity on structured and unstructured grids. We note that previous hybrid methods [1] are first order and presented for structured grids.
The Darcy-flux is approximated by a control-volume distributed multipoint flux approximation (CVD-MPFA) coupled with a higher resolution approximation for convective transport. The CVD-MPFA method is used for Darcy-flux approximations involving pressure and gravity flux operators, leading to a novel formulation for two-phase and three-component two-phase flow on unstructured grids.
Comparisons with both higher resolution and standard first order characteristic based upwind methods and classical phase upwinding is presented.
Results demonstrate the benefits of the new methods for a range of problems including channel flow and shale-barrier problems.
[1] S. Lee, Y. Efendiev, H. Tchelepi, Hybrid upwind discretization of nonlinear two phase flow with gravity, Advances in Water Resources 82 (2015) 27–38.
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Complex-Structured Reservoir Modeling On Dynamically Adaptive PEBI-Grids
Authors D.D. Filippov, I.Yu. Kudryashov, D.Yu. Maksimov, D.A. Mitrushkin and A.P. RosSummaryThe paper considers generation and application of dynamically adaptive unstructured PEBI-grids for adequate multiphase flow modeling of complex-structured reservoirs exploited by horizontal and deviated wells, including wells with single or multistage hydraulic fractures.
We developed methods for constructing PEBI-grids which are more detailed near the reservoir structural features (wells, natural faults, hydraulic fractures and reservoir boundaries) and sparse away from them. These grids make it possible to increase the accuracy of flow treatment in the vicinity of operational objects, without significant slowing down of the entire calculation. A number of algorithms for constructing the PEBI-grid are developed to account for non-vertical geological faults with a complex structure (normal fault, reverse fault), the real geometry of hydraulic fracturing and hydraulically connected natural fractures obtained from a geomechanical simulator.
On grids under consideration, three-phase flow problem, accounting for gravitational, viscous and capillary forces and phase transition of hydrocarbon components is solved numerically. Within the framework of the paper, the approach of the direct calculation of the inflow to and the flow inside hydraulic fractures is developed and implemented. Two-point flux approximation and mimetic finite difference are used for solving three-phase flow problem.
We developed the algorithm of local grid rearrangement due to newly opened wells and hydraulic fractures growth (including waterflood-induced fracturing) that reduces simulation time.
Results of calculations showing the speed, accuracy and physical adequacy of the proposed approach to the reservoir modeling of complex-structured reservoirs are presented.
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Local Forward-Mode Automatic Differentiation For High Performance Parallel Pilot-Level Reservoir Simulation
Authors A. Lauser, A.F. Rasmussen, T.H. Sandve and H.M. NilsenSummaryLocal forward-mode automatic differentiation for high performance parallel pilot-level reservoir simulation. Robust reservoir simulation requires accurate linearization and involve complex property evaluations and dynamics. Handcoded Jacobian derivative calculations require significant resources to maintain and change, when taking into account all needed features for industrially relevant simulations. Automatic differentiation (AD) is a technique which gives machine precision accuracy of derivatives while requiring minimal extra effort, essentially only requiring the implementation of the residual equations. This makes extending the model simpler and less error-prone.
The optimal use of AD techniques depend on the particular grid structures and discretizations used. Here we present how local forward-mode AD can be used with a discretization based on the Distributed Uniform Numerics Enviroment (DUNE) grid interface to achieve a high performance reservoir simulator.
This paper discusses how one can exploit the structure of the full reservoir equations to obtain a dense data representation with only local evaluations in the AD framework, thereby avoiding excessive treatment of sparse sets or matrices. We highlight aspects of the C++ implementation which contribute to giving clean code, parallel performance and efficient use of modern microprocessors. Finally, the OPM Flow simulator is used to demonstrate the approach on field case examples.
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Design Unstructured Grids For Modeling Complex Fields Of Oil Deposits
Authors O.N. Turar, D.Zh. Akhmed-Zaki and D.V. LebedevSummaryMost of the existing algorithms of unstructured grid construction are designed based on the simple geometry and graph paradigms. Such approach may lead to close placement of different size cells sometimes. But considering the fact that it is continuous physical values to be discretized on constructed grids scientists mostly need deliberate changing of cell size.
The paper offers paradigm of using of differential equations to construct unstructured grids to keep valuable characteristics of cells as suitable for physical value discretization as possible. Such methods are being widely used for adaptive structured grid construction in many branches of computational physics industry. One of the main reasons of such prevalence is its physicality together with its intuitiveness and convenience for finite differential computations. In case of finite volume and finite element methods the role of physicality is also very important. It can be provided by using of differential equations to determine the positions of the cells and nodes of the grid. The smoothness of grid cell size changes can be granted by tension of diffusion to bring values to average. Consequently, using of elliptic and parabolic differential equations will lead to unstructured grids smooth in terms of cell size.
In this paper we used the method of construction based on solving Beltrami equation. This equation represents a diffuse spread of coordinate values on some specific metric. The nodes and cell centers in this situation would evenly spread over some abstract surface with this metric. On simple cartesian space it leads to curvilinearly adapted grid. The smoothness of the metric further guarantees smoothness of the grid.
At the same time cells keep basic criteria of the unstructured computational grids such as Delaunay criterion. It’s due to the fact that solving the equation only defines spread of points’ set and grid itself constructed using standard methods. This approach allows to construct physically adequate computational grids in case of geo-modelling with complicated structure and complex form of the field.
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Improving Peaceman Well Flow Modelling With 1D Radial Simulation
By H. CuiSummaryIn reservoir simulation, Peaceman’s method is the most popular solution for simulating the flow from the reservoir to the well by knowing the gridblock and wellbore pressures, and the fluid phase properties in the well block. The Peaceman method is easy to implement and works well if there are no phase changes in the wellblock. A gas-condensate field is an example of a phase-change situation. When the pressure falls below the dewpoint, condensate drops out in the reservoir and accumulates near the wellbore. The gas relative permeability falls and the well productivity is affected. Evaluating the reservoir fluid phase behaviour using the gridblock pressure will give an incorrect value for well flow productivity. Rigorous well flow simulation requires a very fine grid level that demands a large computational effort. There are various methods for obtaining a detailed pressure profile around wells, for example, the pseudo-pressure method, local grid refinement and hybrid gridding. However, these methods either require many assumptions to estimate the phase properties (as in the pseudo pressure method) or a dedicated gridding technique (as in the local grid refinement method and hybrid gridding), or perform poorly.
In the present work, the Peaceman well flow modelling method has been improved with 1D radial simulation to mimics the local physics around a well accurately with little computational effort. For that goal, a local 1D cylindrical radial flow from the equivalent radius to the well bore was considered. Within the wellblock, cylindrical co-ordinates are used, with the well’s axis being the z-axis. Each radial node represents an annulus around the z-axis extending from the entry point to the exit point of the well in the wellblock in 3D space. Because the grid and internode properties of the radial nodes can be calculated analytically, there is no need to generate these nodes in the real grid space. In our present work, we have mapped the blocks generated by the local grid refinement to the 1D radial nodes. As these radial nodes are real model blocks, relative permeability and pressure–volume–temperature modelling are simulated in these blocks without extra effort. The new method is easily adapted by most reservoir simulators that implement the Peaceman method. Numerical experiments show that, with a few extra 1D radial nodes, the method can accurately and efficiently simulate the rapid pressure profile and phase changing within a wellblock.
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Finite Element With Embedded Discontinuities Analysis Of Well Production Decline Due To Fracture Closure In Naturally Fr
Authors L. Beserra, L. Guimarães, O.L. Manzoli and L. BerrioSummaryIn naturally fractured reservoirs, the fractures may represent the main pathway for fluid flow. Therefore, the magnitude of fracture permeability plays a fundamental role in the productivity of such type of reservoir. In reservoirs sensitive to the stress state, the depletion due to production can lead to the closure of the fractures, as a function of the increase of effective confining stress, promoting a significant decrease in the overall permeability of the reservoir. Thus, understanding the hydraulic characteristics of the fracture network as a function of the effective confining stress is fundamental for the design of reservoir development, besides the predictability of its behavior.
In this paper, a strong discontinuity approach to embed discontinuities into finite elements was adopted to represent the behavior of fractures in rock formations. To properly derive embedded discontinuity finite element formulations, fundamental aspects regarding to the kinematics and statics of the discontinuity must be considered. The kinematic enrichment must correctly reflect the position of the interface in the element as well as the relative displacement (opening and sliding) between the two opposite faces of the interface. Furthermore, the traction continuity condition must be properly imposed to ensure a correct relationship between the tractions in the internal interface and the stresses in the surrounding continuum portion.
The simulation of the problem of closing natural fractures by reservoir depletion was carried out. A numerical tool was used to embed the natural fracture network into the finite element mesh, with respect to the geological mapping of these fractures. To model the mechanical behavior of material, it was adopted a hyperbolic model of fracture closure proposed by Barton & Bandis. It was possible to observe a decrease in the rate of production due to the collapse of the existing fractures that decreased the permeability around the production wells.
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Modeling Of Stimulated Reservoir Volume By Multistage Hydraulic Fracturing In Formation With Pre-Existing Natural Fractu
Authors A. Erofeev, V. Vostrikova, R. Sitdikov, R. Nikitin and D. MitrushkinSummaryThis article describes a software tool developed by authors for modeling the process of SRV forming. The calculation of the hydraulic fractures growth and the flow of a mixture of liquid and proppant in a network of fractures is carried out within the cell-based Pseudo-3D model. Developed model also takes into account the interaction of hydraulic fractures with natural fractures and «stress shadow» effect. In addition, the implemented tool allows to simulate the deposition of the proppant and the process of fracture closing after stopping the injection. The influence of the main input parameters on SRV formation is investigated, and the simulation results using real data are presented in the article.
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Proppant Transport Modeling With Effects Of Suspension Yield Stress, Jamming, And Filtration Through The Proppant Pack
Authors A.A. Osiptsov, S.A Boronin and E.V DontsovSummaryWe present further development of the 2D two-continua model of proppant transport derived from first principles using the lubrication approximation [1]. The model includes effects associated with presence of the slip velocity between particles and fluid, as well the yield stress of carrying fluid. These features are typically missing in standard, effective-medium models of proppant transport, though power-law rheology is often included. Predictions of model [1] have gone through a thorough validation against a set of carefully selected lab data [2].
It is important to stress the presence of a fundamental issue with standard semi-empirical relationships for suspension rheology, which predict singular behavior near the particle packing limit. One possibility to resolve the issue is to introduce an ad-hoc regularization by stepping out from the singularity at a small epsilon to mimic the transition from flowing suspension to Darcy filtration through the packed bed. Clearly, such a regularization is unable to accurately describe the physics for all possible scenarios since the flux has a different dependence on the channel width for Poiseuille and Darcy flows. Alternatively, one may utilize a recently developed suspension flow model [3], in which the issue of singular behavior is resolved by developing the model from first principles. The latter approach is physics-based, self-consistent, and covers the entire range of variation of the particle volume fraction, from dilute through dense to granular pack, and in particular predicts Darcy filtration at the packing limit.
Here, we will present a proppant transport model that accounts for the combined effects of particle jamming due to bridging, dehydration, and transition to close packing, combined with Bingham rheology of the suspension (induced by cross-linking of the polymer-based fracturing fluid, presence of fibers, and suspension rheology itself near the packing limit). We use a unified closure relation for the suspension rheology proposed recently in [3] to cover the whole range of proppant concentration, from dilute suspension, to dense and close packing. Numerical results are given to illustrate the newly introduced effects.
References:
- Osiptsov, A.A., 2017. Fluid Mechanics of Hydraulic Fracturing: a Review. J. Petrol. Sci. Eng. V. 156, July 2017, pp. 513–535.
- Boronin, S.A., Osiptsov, A.A. and Desroches, J., 2015. Displacement of yield-stress fluids in a fracture. International Journal of Multiphase Flow, 76, pp.47–63.
- Dontsov, E.V., and Peirce, A.P., 2014. Slurry flow, gravitational settling, and a proppant transport model for hydraulic fractures. Journal of Fluid Mechanics , 760, 567–590.
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Assimilation Of Microseismic Data Into Coupled Flow And Geomechanics Models
Authors S Hakim-Elahi and B. JafarpourSummaryGeologic CO2 storage in deep saline aquifers requires reliable risk assessment to evaluate and minimize unintended consequences such as potential CO2 leakage and induced seismicity. To mitigate such risks continuous monitoring and model updating is needed to improve future predictions and risk assessment. Injection-induced microseismicity has been proposed as a monitoring technique that can be used to constrain rock flow and mechanical properties. We present our ongoing work to develop a framework for assimilation of microseismic monitoring data for estimation of rock mechanical properties using coupled flow and geomechanics simulation as a forward model. Coupled flow and geomechanics simulation is combined with Mohr-Coulomb failure criterion and a stochastic measurement model, to provide a rigorous approach for prediction and interpretation of spatiotemporal distribution of discrete microseismic events in the formation. The focus of the paper is on building a geomechanics-based stochastic framework that can be used to establish physical correlation among rock mechanical properties and microseismic response data. The resulting correlations can then be used to estimate rock properties from observed microseismic clouds. In this paper, we present the developed framework and preliminary results to evaluate its performance for integration of microseismic data.
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Characterization Of Liquid Bridge Formed During Gas-Oil Gravity Drainage In Fractured Porous Media
Authors B. Harimi, M. Masihi, M.H. Ghazanfari and A. ShoushtariSummaryGas–oil gravity drainage that takes place in the gas-invaded zone of fractured reservoirs is the main production mechanism of gas-cap drive fractured reservoirs as well as fractured reservoirs subjected to gas injection. Interaction of neighboring matrix blocks through reinfiltration and capillary continuity effects controls the efficiency of gravity drainage. Existence of capillary continuity between adjacent matrix block is likely to increase the ultimate recovery significantly. Liquid bridge formed in fractures has a significant role in maintaining the capillary continuity between two neighboring matrix blocks. The degree of capillary continuity is proportional to capillary pressure in the fracture due to the presence of formed liquid bridge. Only a handful of studies have focused on the subject of liquid bridge in fractures and related capillary pressure. The main contribution is to develop a numerical procedure to predict liquid bridge characteristics (e.g. its shape, its stability and its capillary pressure). Accurate determination of gas-liquid interface profile of liquid bridge is crucial to predict fracture capillary pressure precisely. To this end, numerical solution of Young-Laplace equation in the absence and in the presence of gravitational effects is found and the obtained results are verified by the experimental data. Computation of fracture capillary pressure as a function of liquid bridge volume for different contact angles revealed that the fracture capillary pressure-liquid saturation curve has a shape similar to that of a matrix. Therefore, the capillary pressure of porous media can be applied directly for fractures considering proper modifications. Furthermore, the stability of liquid bridge has been investigated using the concept of critical fracture aperture. Critical fracture aperture is defined as the maximum fracture aperture that a liquid bridge with specific volume can exist. Finally, an empirical relation has been developed that correlates the critical fracture aperture to both the liquid bridge volume and the contact angle. Results of this study emphasize the importance of capillary continuity created by liquid bridges and therefore, incorporation of liquid bridges in the study of gas-oil gravity drainage will lead to more realistic performance prediction of fractured porous media.
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Algebraic Dynamic Multilevel Method for Single-phase Flow in Heterogeneous Geothermal Reservoirs
Authors M. HosseiniMehr, R.B. Arbarim, M. Cusini, C. Vuik and H. HajibeygiSummaryAccurate numerical simulation of coupled fluid flow and heat transfer in heterogeneous geothermal reservoirs demand for high resolution computational grids. The resulting fine-scale discrete systems--though crucial for accurate predictions--are typically upscaled to lower resolution systems due to computational efficiency concerns. Therefore, advanced scalable methods which are efficient and accurate for real-field applications are more than ever on demand. To address this need, we present an algebraic dynamic multilevel method for flow and heat transfer in heterogeneous formations, which allows for different temperature values for fluid and rock. The fine-scale fully-implicit discrete system is mapped to a dynamic multilevel grid, the solution at which are connected through local basis functions. These dynamic grid cells are imposed such that the sub-domain of sharp gradients are resolved at fine-scale, while the rest of the domain remains at lower (coarser) resolutions. In order to guarantee the quality of the local (heat front) components, advanced multiscale basis functions are employed for global (fluid pressure and rock temperature) unknowns at coarser grids. Numerical test cases are presented for homogeneous and heterogeneous domains, where ADM employs only a small fraction of the fine-scale grids to find accurate complex nonlinear thermal flow solutions. As such, it develops a promising scalable framework for field-scale geothermal simulations.
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The Application Of Dual Porosity Flow Diagnostics To A Fractured Carbonate Field
Authors V.E. Spooner, S. Geiger, D. Arnold and J.P. NørgårdSummaryIn this study we have applied new dual-porosity flow diagnostics to a recently discovered offshore fractured carbonate reservoir undergoing charactersiation studies. Carbonate reservoirs are typically highly hetrogeneous, naturally fractured and often mixed to oil wet, all of these factors are uncertain and can negatively impact upon recovery. With few wells drilled at the time of this study significant uncertainty hinders robust decision making. A robust multi-realisation approach is rendered impractical as the run time for a single realisation of the dual-porosity model is in excess of several days. Instead of using brute force we have utilised grid based flow diagnostics as a fast screening tool to select reservoir models for further full-physics simulations. The CPU time of flow diagnostics is almost negligable. Flow diagnostics are numerical tests perfomed on the static model that provide the time-of-flight, tracer partitions, drained/swept volumes and well pairs. In addition, dual-porosity metrics link the advective flow in the fractures to transfer from the matrix, indicating regions where flow and transfer are unbalanced and hence at risk of early breakthrough.
Over 30 flow diagnostic tests were performed in under 10 minutes, the equivalent screening would take weeks using simulation. Results have shown that the fracture intensity and wettability are the most signifcant uncertainties that impact upon transfer and recovery, this effect would be missed by an equivalent single-porosity model. Well placement in this reservoir is very sensitive; the results show the proposed placement is effective for the assumed yet uncertain facies distribution. This broad sensitity screening has guided the ongoing modelling strategy, in partcular pinpointing the need for detailed characterisation of the fracture and facies distributions. Flow diagnostics are hence an excellent way to complement production forecasting workflows by providing a tool for quickly ranking and selecting scenarios for further detailed full-physics simulation, allowing us to focus more computational resources on reservoir models that are of particular interest.
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Multi-Level Discrete Fracture Model For Carbonate Reservoirs
More LessSummaryThe main challenge for predictive simulation of carbonate reservoirs is associated with large uncertainties in the geological characterization with multiple features including fractures and cavities. This type of reservoirs requires robust and efficient forward-simulation capabilities to apply data assimilation or optimization technique under uncertainties. The interaction between reservoir matrix and various features introduces a complex multi-scale flow response driven by global boundary conditions. The Discrete Fracture Models (DFM), which represent fractures explicitly, is capable to accurately depict all important features of flow behavior. However, these models are constrained by many degrees of freedom when the fracture network becomes complicated. The Embedded DFM, which represents the interaction between matrix and fractures analytically, is an efficient approximation. However, it cannot accurately reproduce the effect of local flow conditions, especially when the secondary fractures are present. In this study, we applied a numerical upscaling of DFM a triple continuum model where large features are represented explicitly using the numerical EDFM and small features are upscaled as a third continuum. In this approach, we discretize the original geo-model with unstructured grid based on DFM and associate the mesh geometry with large features in the model. Using the global solution, we generate local boundary conditions for the model capturing the response of primary features to the flow. Applying local boundary conditions, we resolve all secondary features using a fine scale solution and update the local boundary conditions. This procedure is applied iteratively using the local-global-upscaling formalism. To demonstrate the accuracy of the Multi-Level Discrete Fracture Model, several realistic cases have been tested. By comparing with fine scale DFM solution and the traditional EDFM technique, we demonstrate that the proposed model is accurate enough to capture the flow behavior in complex fractured systems with advanced computational efficiency.
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Numerical Simulation Of Low Salinity Water Flooding: Wettability Alteration Considerations
Authors A. Jahanbani Ghahfarokhi and O. TorsaeterSummaryThe mechanisms of Low Salinity Water Flooding (LSWF), as a cost-effective and environmentally-friendly technique for improved oil recovery, have been extensively investigated during the last years. Although the mechanisms are still subject of research, wettability alteration (or change in relative permeability) of formation rock surfaces from preferential oil wetness to water wetness as a result of multi-component ion exchange (MIE) and geochemical reactions is a feasible and supported pore scale mechanism. Modeling of wettability alteration process is challenging due to the complex interactions among ions in the brine and crude oil on the solid surface. To improve the understanding of the influence of geochemical processes on the LSWF, numerical models were created with parameters identical to those used in the experiments. The low salinity effects were simulated using a numerical reservoir simulator, considering aqueous reactions, ion exchange, and mineral dissolution and precipitation. Characteristic features of the model are explored in order to gain insight into the role of low salinity flooding, and its possible impact on oil recovery.
The model was used to predict oil recovery for experiments under a variety of conditions where recovery factor may be increased by about 30 %. The geochemical reactions included in the model control the wetting fractions and contact angles, which subsequently determine the capillary pressure, relative permeabilities, and residual oil saturations.
Simulations show that transport of the phases is related to desorption of the divalent ions from the clay surface in such a way that increased desorption gives rise to a change of the relative permeabilities such that more oil is mobilized. Dissolution of calcite tends to reduce desorption of calcium ions from the rock surface and hence the possibility to improve recovery by the MIE mechanism. The release of cations and hence oil recovery depend on several factors like connate water and brine compositions, and clay content. It can be concluded based on this study that the LSWF performance depends on initial wettability conditions, clay content and reservoir minerals, composition of the injected and formation water, and also oil properties.
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Micro-Scale Simulation Of Hybrid Solvent-Based Oil Recovery
Authors I.I. Bogdanov, M. Mujica and O. GarnierSummaryThe laboratory measurements based on micromodel setup (lab-on a-chip technology) is rapidly developing and promising domain in porous media and microfluidics applications. Taking advantage of recent tests of solvent injection we developed a multicomponent model and did a numerical analysis of the micro-scale model design and the oil recovery process parameters.
Hybrid solvent-based thermal technology offers efficient and sustainable oil recovery. The main idea of such a process is a significant and controllable reduction of oil viscosity in particular via solvent-to-original-oil mixing and also additional effect related to local heating.
After studying the dynamics of solvent-to-oil mixing and upscaling of micro-scale model properties, the multicomponent simulations were done to adapt the micromodel design for experimental study and measurements of solvent-based recovery, to identify the key process parameters, and to specify their estimation procedure. Two principal flow configurations were considered with gravity-stabilized vertical and horizontal oil displacement.
Being evidently not capable to capture in detail a pore-scale fluid dynamics, the developed numerical model has demonstrated its usefulness both for model design and experimental results analysis, and offered the framework for quantitative determination of some process parameters. The discussion is provided on each step of corresponding adaptation of the simulation model.
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Compositional-Dependent Viscosities In Microemulsion Systems
Authors D. Magzymov, P. Khodaparast and R.T. JohnsSummaryAccurate estimates of compositional-dependent microemulsion viscosities are critical to model flow in surfactant-polymer floods. Microemulsions are mixtures of oil, water and surfactant with complex internal structures and interaction forces between components. This paper develops a physics-based microemulsion viscosity model at low shear rate for compositional variations within a fixed ternary surfactant-brine-oil system. Our proposed model generates continuous viscosities for the entire compositional space with honored physical limits. First, binary water-surfactant and oil-surfactant viscosities variations along the axes of the ternary diagram are captured. Second, viscosity peaks at the “percolation locus” are reproduced, where the percolation locus is defined by hypothetical single-phase compositions within the ternary diagram. Last, end-point viscosities of pure water and oil on the apex of the ternary diagram are honored. The results show that the new model fits and predicts single phase microemulsion viscosities in ternary compositional space with acceptable accuracy (R2> 0.75) for a challenging three pseudocomponent system of isooctane, decane, and cyclohexane mixed with water and surfactant. The first-of-its-kind viscosity model can be coupled with any microemulsion phase behavior equations of state, such as that based on HLD-NAC.
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Estimation Of CO2 Penetrating Pore Throat Diameter Based On CO2 Miscible Flood Experimental Results
Authors H. Yonebayashi, K. Takabayashi, Y. Miyagawa, T. Watanabe, T. Yamada and H. KaiSummaryCO2 enhanced oil recovery (EOR) has been commercially applied all over the world to produce more oil. The CO2 function is to attain minimum miscibility pressures at reasonably low pressure compared with reservoir pressure. This generates CO2 miscible flooding leading to more preferable oil recovery. Even under such a preferable condition, 100% oil recovery is rarely seen in laboratory experiments: coreflood and slimtube tests. However, compositional simulation of gas-injection sometimes predicted zero oil saturation in certain grids. To decrease a gap between practical and numerical phenomenon, Hiraiwa et al. (2007) developed a method of incorporating residual oil saturation obtained in laboratory coreflood experiments. The concept of Sorm was defined as the residual oil saturation that did not decrease less than user-prescribed values. To evaluate CO2 EOR more practically, the laboratory results were used to estimate Sorm in core scale for numerical modelling. This paper presents extensive laboratory results of unsteady state oil displacement by 15PV CO2 much more than usual CO2 coreflood experiments of 2–3 PV. By properly considering such on-site reality into account for laboratory core flooding design, a core scale Sorm can be obtained. Based on the Sorm, CO2-penetrating pore throat size was discussed in this study.
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Modelling Sweep Efficiency Improvement By In-Situ Foam Generation Using A Dispersed Surfactant In The Gas Phase
Authors J.D. Valencia, J.M. Mejia and A. OcampoSummaryFoam in porous media is a proven method to improve the sweep efficiency of a Flooding fluid in EOR process and the effectiveness of a treatment fluid in well intervention procedures. Foams are often generated by SAG (Surfactant alternating gas) or co-injection methods, although these operations result in excellent incremental production, profit losses could be high due to high surfactant retention and lack of water injection facilities in some target oil fields. One way of reducing operational costs is by injecting surfactant disperse throughout the gas phase in a process called “Disperse Foam”. Core flooding experimental results have proven that disperse foam technique can reduce surfactant retention kinetics and increase cumulative oil production, Additionally, the injection upscaling from laboratory to field reduces significantly operational cost. Because few laboratory core tests and field pilots have been implemented using disperse foam technique, there is high uncertainty associated to this process. Moreover, literature models do not account for all the associated phenomena, including surfactant transfer between gas and liquid phases, and the lamellae stability at low water saturations. Hence, the development of a disperse foam mechanistic model is key to understand disperse foam operations phenomena. In this work, a mathematical model is developed, the model accounts for surfactant mass transference between gas and liquid phases in non-equilibrium using a particle interception model, dynamic surfactant adsorption on the rock surface with a first order kinetic model and foam kinetics using a population balance mechanistic model.
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Three Dimensional Modeling Of Enhanced Oil Recovery With Surfactants And Displacement By Polymers Based On Streamline Si
Authors M. Kurmanseiit, N. Shayakhmetov, A. Kuljabekov, D. Aizhulov and T. ImankulovSummaryMain objective of present work was three dimensional simulation of the techniques of enhanced oil recovery with streamline approach. In order to demonstrate high efficiency of oil displacement with the use of polymers and thermal effects, distribution of the saturation of the aqueous phase, the concentration of the polymer and the thermal effects were determined along the streamline. Streamline simulation approach was further evaluated to determine its limitations and advantages when applied to enhanced oil recovery. Model can be applied to determine efficiency of various approaches of enhanced oil recovery, based on the sequence of injection of polymers and surfactants. Additionally, the model accounts for pore clogging by polymers, temperature effects and influence of salt concentration. Computational speed as well as calculation accuracy are increased with the application of streamline simulation and parallel technologies such as GPU based computing.
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Model Development And Validation For Chemical Droplets Injection In Gas Phase In Eor Applications
Authors J.D. Valencia, J.M. Mejia and A. OcampoSummaryThe chemically enhanced gas injection technology (ChEGas-EOR) is a novel technique developed by “Equion Energia” in association with the “Universidad Nacional de Colombia”. In this technique, a liquid treatment having engineered properties is sprayed along with the gas stream in gas injector wells to increase the oil recovery factor in oil reservoirs. Previous lab tests, pilot studies in light & intermediate oil reservoirs indicate that the application of ChEgas-EOR allows for a reduction in operational costs, increases the chemical penetration radii and decreases the retention rate in the rock. However, the associated uncertainty is still too high to develop this process on a productive scale. For this reason, development of a phenomenological model is key to understand the mechanism related to disperse chemical injection and its effects on reservoir oil flow. In this work, we developed a phenomenological model to assist in design and evaluation of Chemical Gas EOR operations aiming to reduce the uncertainties and understand the optimize oil recovery. The model accounts for the chemical mass transfer between phases in a non-equilibrium state with an interception model, a dissolution model and a first order kinetic model for the surfactant sorption on the rock. The tool was calibrated with experimental data and with the adjusted parameters upscale to reservoir conditions to forecast the oil production in field pilots getting good agreement.
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