A Semi Analytical Streamline Simulation In Near Wellbore Regions And Its Applications Under Constant Pressure Boundaries
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A Semi Analytical Streamline Simulation In Near Wellbore Regions And Its Applications Under Constant Pressure Boundaries
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Author : Xiaoyan Tang
language : en
Publisher:
Release Date : 2017
A Semi Analytical Streamline Simulation In Near Wellbore Regions And Its Applications Under Constant Pressure Boundaries written by Xiaoyan Tang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Streamline simulation is a powerful tool that can be used for full field forecasting, history matching, flood optimization, and displacement visualization. This research thesis presents the extension of a semi-analytical streamline simulation method and its application in the near-wellbore region in two-dimensional polar coordinate systems and three-dimensional cylindrical coordinate systems. The main objective of this research thesis is to study the effects of the permeability heterogeneity and well completion details in the near-wellbore region. These effects dictate the streamline geometries, which in turn influence well productivity. It is revealed that the semianalytical streamline simulation method developed in this research thesis is the only known streamline method with sufficient accuracy for streamline simulation in polar/ cylindrical geometries. Previous streamline applications used a constant flow rate condition for each stream tube. However, wells in low permeability reservoirs are often produced at constant pressure. In this research thesis, streamline simulation is performed under constant pressure boundaries. This is a novel and non-trivial extension of streamline simulation. The semi-anlytical streamline method is applied in the perforated wells. Results indicate that it is the only method that can accurately simulate the streamline path in such wells. A new skin calculation method based on the semi-anlytical streamline simulation method is introduced and applied in perforated wells. This new skin calculation method is believed to be superior and can be used to examine the effect of the perforation parameters. It provides useful information for evaluating the well completion strategy. In this work, the two-phase displacement process is simulated along stream tubes. Solutions are constructed by treating each stream tube as a flow unit by invoking novel analytical solutions for such geometries. Visualization experiments are direct ways to investigate the effect of the heterogeneity on flow distribution. Two-dimensional radial waterflooding visualization experiments are performed under constant pressure boundaries for homogeneous and heterogeneous porous media. The homogenous case is used to history match and determine the relative permeabilities. Using these relative permeabilities, the semi-analytical streamline simulation method is independently validated against the results from the heterogeneous visualization experiments.
A New Semi Analytical Streamline Simulator And Its Applications To Modelling Waterflooding Experiments
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Author : Nan Zhang
language : en
Publisher:
Release Date : 2017
A New Semi Analytical Streamline Simulator And Its Applications To Modelling Waterflooding Experiments written by Nan Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Reservoir simulation is a tool to model the fluid flow in a reservoir over time. Streamline simulation has been proven to be an efficient approach for fine-scale geology models. With the development of engineering applications of streamline methods, researchers are now facing more challenges, for example, 1) tracing streamlines in structurally complex reservoirs; 2) improving the computational accuracy and efficiency for modeling transport problems. This research offers significant potential to meet these challenges. More specifically, this research is mainly focused on the development of a new three-dimensional, two-phase streamline simulator (using Matlab) that can model real physical displacement processes in a fast and accurate manner. This streamline simulator solves the pressure and saturation equations sequentially. First, streamlines are traced by pressure distribution approximations; and then transport problems are solved along streamlines. This new streamline simulator applies new semi-analytical methods to trace streamlines, including the Bilinear, Trilinear and Cubic methods. These methods generate streamlines based on pressure distribution approximations using piece-wise polynomials. Then the velocity field, streamline trajectory functions, and time-of-flight (the time a particle takes to travel along a streamline) are derived accordingly. The new streamline method and Pollcok's method are systemically compared via pressure and velocity approximations, plus streamline determinations. Through these comparisons, the new methods are proven to be more accurate than Pollock's method, especially in heterogeneous problems and/or when grid resolution is low. When certain initial conditions are imposed, this new streamline simulator applies a Riemann approach to solving transport problems along streamlines. Standard streamline simulators apply the classical Riemann solution under constant total flow rate conditions. However, the boundary conditions can also be specified by constant injection and production pressures. In this case, the flow rate varies with time, and a new semi-analytical Riemann solver presented in this thesis can be applied to map the Riemann solution along streamlines in terms of time-of-flight. Through a series of case studies using different reservoir properties, the abilities of the new streamline simulator to give sufficiently accurate solutions for homogeneous, heterogeneous, and anisotropic problems are demonstrated. Moreover, a large mobility ratio range (0.5 to 50) is tested to evaluate the performance of this streamline simulator. Through comparisons with a standard reservoir simulator (Eclipse100, Schlumberger) in these cases studies, it is demonstrated that this new streamline simulator significantly enhances the calculation speed and improves the accuracy of simulations when the underlying assumptions are valid. Finally, the ability of the new simulator is validated and demonstrated by modeling physical waterflooding displacements. This is the first time that waterflooding experiments are performed under constant differential pressure boundaries in a two-dimensional heterogeneous macro-model. Two experiments with the same reservoir and fluid properties are performed under different boundary conditions. The new simulator is applied to history match and simulate these two experiments. The predicted and observed results show excellent agreement. The flow behavior of the fluid under a constant pressure boundary is also well understood by using the visual power of the simulator. We conclude that the new streamline simulator is very efficient and accurate in physical waterflooding processes simulations when the viscous force dominates the flow.
Near Wellbore Streamline Modeling For Advanced Well Completions
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Author : Justin Harry Skinner
language : en
Publisher:
Release Date : 2011
Near Wellbore Streamline Modeling For Advanced Well Completions written by Justin Harry Skinner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 1997
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Dissertations, Academic categories.
An Embedded Method For Near Wellbore Streamline Simulation
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Author : Bin Wang
language : en
Publisher:
Release Date : 2017
An Embedded Method For Near Wellbore Streamline Simulation written by Bin Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Oil reservoir engineering categories.
Application Of Convolution And Average Pressure Approximation For Solving Non Linear Flow Problems
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Author : Mansur Zhakupov
language : en
Publisher:
Release Date : 2006
Application Of Convolution And Average Pressure Approximation For Solving Non Linear Flow Problems written by Mansur Zhakupov and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
The accurate description of fluid flow through porous media allows an engineer to properly analyze past behavior and predict future reservoir performance. In particular, appropriate mathematical models which describe fluid flow through porous media can be applied to well test and production data analysis. Such applications result in estimating important reservoir properties such as formation permeability, skin-factor, reservoir size, etc. "Real gas" flow problems (i.e., problems where the gas properties are specifically taken as implicit functions of pressure, temperature, and composition) are particularly challenging because the diffusivity equation for the "real gas" flow case is strongly non-linear. Whereas different methods exist which allow us to approximate the solution of the real gas diffusivity equation, all of these approximate methods have limitations. Whether in terms of limited applicability (say a specific pressure range), or due to the relative complexity (e.g., iterative character of the solution), each of the existing approximate solutions does have disadvantages. The purpose of this work is to provide a solution mechanism for the case of time-dependent real gas flow which contains as few "limitations" as possible. In this work, we provide an approach which combines the so-called average pressure approximation, a convolution for the right-hand-side non-linearity, and the Laplace transformation (original concept was put forth by Mireles and Blasingame). Mireles and Blasingame used a similar scheme to solve the real gas flow problem conditioned by the constant rate inner boundary condition. In this work we provide solution schemes to solve the constant pressure inner boundary condition problem. Our new semi-analytical solution was developed and implemented in the form of a direct (non-iterative) numerical procedure and successfully verified against numerical simulation. Our work shows that while the validity of this approach does have its own assumptions (in particular, referencing the right-hand-side non-linearity to average reservoir pressure (similar to Mireles andBlasingame)), these assumptions are proved to be much less restrictive than those required by existing methods of solution for this problem. We believe that the accuracy of the proposed solution makes it universally applicable for gas reservoir engineering. This suggestion is based on the fact that no pseudotime formulation is used. We note that there are pseudotime implementations for this problem, but we also note that pseudotime requires a priori knowledge of the pressure distribution in the reservoir or iteration on gas-in-place. Our new approach has no such restrictions. In order to determine limits of validity of the proposed approach (i.e., the limitations imposed by the underlining assumptions), we discuss the nature of the average pressure approximation (which is the basis for this work). And, in order to prove the universal applicability of this approach, we have also applied this methodology to resolve the time-dependent inner boundary condition for real gas flow in reservoirs.
Near Well Bore Streamline Simulation
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Author : Marjan Hashem
language : en
Publisher:
Release Date : 2011
Near Well Bore Streamline Simulation written by Marjan Hashem and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Boring categories.
A Numerical Sensitivity Analysis Of Streamline Simulation
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Author : Fady Ruben Chaban Habib
language : en
Publisher:
Release Date : 2005
A Numerical Sensitivity Analysis Of Streamline Simulation written by Fady Ruben Chaban Habib and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with categories.
Nowadays, field development strategy has become increasingly dependent on the results of reservoir simulation models. Reservoir studies demand fast and efficient results to make investment decisions that require a reasonable trade off between accuracy and simulation time. One of the suitable options to fulfill this requirement is streamline reservoir simulation technology, which has become very popular in the last few years. Streamline (SL) simulation provides an attractive alternative to conventional reservoir simulation because SL offers high computational efficiency and minimizes numerical diffusion and grid orientation effects. However, streamline methods have weaknesses incorporating complex physical processes and can also suffer numerical accuracy problems. The main objective of this research is to evaluate the numerical accuracy of the latest SL technology, and examine the influence of different factors that may impact the solution of SL simulation models. An extensive number of numerical experiments based on sensitivity analysis were performed to determine the effects of various influential elements on the stability and results of the solution. Those experiments were applied to various models to identify the impact of factors such as mobility ratios, mapping of saturation methods, number of streamlines, time step sizes, and gravity effects. This study provides a detailed investigation of some fundamental issues that are currently unresolved in streamline simulation.
Development And Application Of A 3d Equation Of State Compositional Fluid Flow Simulator In Cylindrical Coordinates For Near Wellbore Phenomena
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Author : Rohollah Abdollah Pour
language : en
Publisher:
Release Date : 2011
Development And Application Of A 3d Equation Of State Compositional Fluid Flow Simulator In Cylindrical Coordinates For Near Wellbore Phenomena written by Rohollah Abdollah Pour and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Well logs and formation testers are routinely used for detection and quantification of hydrocarbon reserves. Overbalanced drilling causes invasion of mud filtrate into permeable rocks, hence radial displacement of in-situ saturating fluids away from the wellbore. The spatial distribution of fluids in the near-wellbore region remains affected by a multitude of petrophysical and fluid factors originating from the process of mud-filtrate invasion. Consequently, depending on the type of drilling mud (e.g. water- and oil-base muds) and the influence of mud filtrate, well logs and formation-tester measurements are sensitive to a combination of in-situ (original) fluids and mud filtrate in addition to petrophysical properties of the invaded formations. This behavior can often impair the reliable assessment of hydrocarbon saturation and formation storage/mobility. The effect of mud-filtrate invasion on well logs and formation-tester measurements acquired in vertical wells has been extensively documented in the past. Much work is still needed to understand and quantify the influence of mud-filtrate invasion on well logs acquired in horizontal and deviated wells, where the spatial distribution of fluids in the near-wellbore region is not axial-symmetric in general, and can be appreciably affected by gravity segregation, permeability anisotropy, capillary pressure, and flow barriers. This dissertation develops a general algorithm to simulate the process of mud-filtrate invasion in vertical and deviated wells for drilling conditions that involve water- and oil-base mud. The algorithm is formulated in cylindrical coordinates to take advantage of the geometrical embedding imposed by the wellbore in the spatial distribution of fluids within invaded formations. In addition, the algorithm reproduces the formation of mudcake due to invasion in permeable formations and allows the simulation of pressure and fractional flow-rate measurements acquired with dual-packer and point-probe formation testers after the onset of invasion. An equation-of-state (EOS) formulation is invoked to simulate invasion with both water- and oil-base muds into rock formations saturated with water, oil, gas, or stable combinations of the three fluids. The algorithm also allows the simulation of physical dispersion, fluid miscibility, and wettability alteration. Discretized fluid flow equations are solved with an implicit pressure and explicit concentration (IMPEC) scheme. Thermodynamic equilibrium and mass balance, together with volume constraint equations govern the time-space evolution of molar and fluid-phase concentrations. Calculations of pressure-volume-temperature (PVT) properties of the hydrocarbon phase are performed with Peng-Robinson's equation of state. A full-tensor permeability formulation is implemented with mass balance equations to accurately model fluid flow behavior in horizontal and deviated wells. The simulator is rigorously and successfully verified with both analytical solutions and commercial simulators. Numerical simulations performed over a wide range of fluid and petrophysical conditions confirm the strong influence that well deviation angle can have on the spatial distribution of fluid saturation resulting from invasion, especially in the vicinity of flow barriers. Analysis on the effect of physical dispersion on the radial distribution of salt concentration shows that electrical resistivity logs could be greatly affected by salt dispersivity when the invading fluid has lower salinity than in-situ water. The effect of emulsifiers and oil-wetting agents present in oil-base mud was studied to quantify wettability alteration and changes in residual water saturation. It was found that wettability alteration releases a fraction of otherwise irreducible water during invasion and this causes electrical resistivity logs to exhibit an abnormal trend from shallow- to deep-sensing apparent resistivity. Simulation of formation-tester measurements acquired in deviated wells indicates that (i) invasion increases the pressure drop during both drawdown and buildup regimes, (ii) bed-boundary effects increase as the wellbore deviation angle increases, and (iii) a probe facing upward around the perimeter of the wellbore achieves the fastest fluid clean-up when the density of invading fluid is larger than that of in-situ fluid.
Timestep Selection During Streamline Simulation Via Transverse Flux Correction
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Author : Ichiro Osako
language : en
Publisher:
Release Date : 2004
Timestep Selection During Streamline Simulation Via Transverse Flux Correction written by Ichiro Osako and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.
Streamline simulators have received increased attention because of their ability to effectively handle multimillion cell detailed geologic models and large simulation models. The efficiency of streamline simulation has relied primarily on their ability to take large timesteps with fewer pressure solutions within an IMPES formulation. However, unlike conventional finite-difference simulators, no clear guidelines are currently available for the choice of timestep for pressure and velocity updates. That is why we need largely an uncontrolled approximation, either managed by engineering judgment or by potentially time-consuming timestep size sensitivity studies early in a project. This will clearly lead us to the lack of understanding of numerical stability and error estimates during the solution. This research presents a novel approach for timestep selection during streamline simulation that is based on three elements. First, we reformulate the equations to be solved by a streamline simulator to include all of the three-dimensional flux terms - both aligned with and transverse to the flow directions. These transverse flux terms are totally neglected within the existing streamline simulation formulations. Second, we propose a simple grid-based corrector algorithm to update the saturation to account for the transverse flux. Third, we provide a discrete CFL (Courant-Friedrich-Levy) formulation for the corrector step that leads to a mechanism to ensure numerical stability via the choice of a stable timestep for pressure updates. This discrete CFL formulation now provides us with the same tools for timestep control as are available within conventional reservoir simulators. We demonstrate the validity and utility of our approach using a series of numerical experiments in homogeneous and heterogeneous ơ five-spot patterns at various mobility ratios. For these numerical experiments, we pay particular attention to favorable mobility ratio displacements, as they are known to be challenging to streamline simulation. Our results clearly demonstrate the impact of the transverse flux correction on the accuracy of the solution and on the appropriate choice of timestep, across a range of mobility ratios. The proposed approach eliminates much of the subjectivity associated with streamline simulation, and provides a basis for automatic control of pressure timestep within full field streamline applications.