Download or read book Semi Analytical Modeling of Fluid Flow in and Formation Evaluation of Unconventional Reservoir Using Boundary Integration Strategies written by Chang Su and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tight oil/gas has been increasingly playing a more and more important role in petroleum industry around the globe for the past two decades and accounting for more share of total production of oil/gas each year. Fractured vertical or horizontal wells contribute most of the tight oil/gas production. Understanding and analyzing fluid flow in the process of fracturing, therefore, become crucial in tight formation production. However, the resulting complexity of fracture propagation from fracture injection test in tight formation, which currently is one the most heated topics for unconventional reservoirs, and heterogeneity problems of tight oil/gas reservoir with non-uniform distribution of rock/fluid properties bring great difficulties in modeling of such complex well-reservoir systems so as to evaluate reservoir characteristics and simulate a variety of reservoir flowing behaviours. Using boundary integration strategies and source and sink function methodology, this dissertation tackles the problems of modeling fracture-propagation-and-closure process along with analyzing the fracture injection test data (mini-fracturing test) in homogeneous reservoir, and modeling of fluid flow in different types of heterogeneous reservoirs. In particular, they are: (1) Analytical Modeling of Fracture Propagation on Evaluation of Transient Pressure Behavior during Injection and after Shut-in: Minifrac Test Analysis by Model-Based Type Curves; (2) Modeling of Multi-stage Fractured Horizontal Well Producing in Multilayered Reservoir with Inter-layer Crossflow; (3) Semi-analytical Modeling of 2-Dimensional Heterogeneous Reservoir by Using Boundary Element Method. II What is presented is that a practical fracture-propagation-and-closure process is modeled, its solution in terms of pressure and leak-off rate behaviors in type curve format is generated and the model-based solutions are applied using curve matching strategy in analyzing field mini-fracturing testing data to evaluate the leak-off rate behavior along a fracture, in order to obtain the fracture geometry, attain an instantaneous shut-in pressure (ISIP), extract reservoir flowing capacity (kh) and detect closure pressure Pc. A reasonable set of parameter solutions can be obtained using the model developed in this study due to a proper modeling of the physical process. Robust analytical results on transient pressure behavior under constant rate and rate response under constant bottom pressure are presented in type curve format as well as inter-layer crossflow for the multilayered reservoir system. By applying boundary element method (BEM), pressure- and rate-transient behaviours of reservoir with multi-scale heterogeneities bounded by arbitrarily shaped boundaries/surfaces are also presented.

Download or read book Semi Analytical Modeling of Fluid Flow and Solid Deformation in Heterogeneous Reservoirs Using Universal Boundary Integral Approaches written by Lei Xiao and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the Canadian oil and gas industry, heavy oil and unconventional reservoirs play a vital role in sustaining the production of crude oil and face tremendous technical challenges of enhancing recovery while reducing environmental footprints. Among various development technologies, the cold heavy oil production with sand (CHOPS) and hydraulic fracturing techniques have been widely applied in Western Canadian basins to unlock the unconsolidated heavy oil and tight formation reservoirs, respectively. Both technologies are proved to be efficient during the primary production period; however, they suffer sharp production decline and low recovery factor. Moreover, during the enhanced oil recovery (EOR) phase, the existence of wormholes and fractures will cause conformance problems and early polymer injection breakthrough. Therefore, better understanding of the wormholes distributions in CHOPS reservoirs and more reliable description of fractures in tight formations become crucial for Canadian operators to design EOR pilots and operate full field applications. Reservoir characterization and modeling of CHOPS reservoirs with wormholes and fractured tight formations face numerous technical issues due to the existence of wormholes and fractures, which make the system no longer homogeneous and cause more complex problems in fluid flow and solid deformation. The boundary element method (BEM), which has been widely applied to solve for fluid flow and solid deformation problems, however, is limited to homogeneous systems. To inherit the merits of BEM such as near-analytical accuracy and negligible space and time subdivision, this research aims at developing boundary integral approaches, as extensions of BEM, to heterogeneous reservoirs with arbitrary wormhole distributions, realistic fracture morphologies, and variation of geological facies. Moreover, field operators have observed that the in-situ stress state will be altered during hydraulic fracturing with associated stress shadow effects. The depletion-induced stress changes will also cause fracture closure and stress reorientation. Accordingly, the boundary integral approaches are further extended to solve for depletion-induced stress change due to poroelastic and mechanical effects in a heterogeneous reservoir with arbitrary distribution of porosity and permeability. The universal boundary integral approaches, which include the integration of various fundamental solutions along boundaries, have been proposed in this study. The developed boundary integral approaches are benchmarked by comparing with analytical solutions and numerical simulations. Representative cases are also presented to analyze complicated heterogeneous problems. Applications of the universal boundary integral approaches for heterogeneous systems are exemplified in the areas of wormhole coverage estimation, pressure and rate transient analysis of heterogeneous reservoirs, spatial-temporal stress evolution of multi-stage fractured horizontal wells, and evaluation of refracturing upside.

Download or read book A Semi Analytical Analysis of the Gas and Water Forecasts from Unconventional Reservoirs written by Abdulla Saleh Alzaabi and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Material balance is an essential reservoir engineering tool that is used to determine original hydrocarbon in place and the production performance of a reservoir. There are several types of material-balance approaches developed, each with its own application. Such approaches include integral material balance, differential material balance and flowing material balance. In this thesis, a form of differential material balance, similar to the one developed by Muskat for Solution Gas Drive Reservoirs, has been derived for unconventional gas-water reservoirs impacted by adsorption. Originally, the developed Muskat-type equation is in the pressure domain, but it can also be derived in other domains such as the time domain and the cumulative produced fluids domains. The resulting system of ordinary differential equations (ODEs) are then solved using fourth order Runge-Kutta method which is a traditional ODE solver. The system of two differential equations for the Muskat-type equation in the time domain (time as an independent variable), are formulated with pressure and water saturation as the dependent variables. These resulting ODEs are then used to forecast and analyze the production profiles of a gas-water reservoir considering adsorption. The semi-analytical model is then validated internally using finite difference and analytical rate derivative equations, and externally by benchmarking it with a numerical simulator. The significant factor that caused the disparity between the semi-analytical model proposed in this study and the numerical simulator is the time it takes to reach pseudo-steady state flow (t_pss) with lower times producing better results. At t_pss less than 0.111 days , numerical simulation is almost replaceable in forecasting rates. However, at t_pss less than 0.717 days, cumulative gas produced can be accurately forecasted. This is to be expected and a reservoir simulator is fully transient, while material balance is based on the pseudo steady-state flow regime. This study provided a unique opportunity to investigate the characteristics of the production profile such as the peak rate and the observed inflection points while also identifying the reservoir parameters that affect them. Moreover, an equation has been developed that can be used to identify and describe the peak rate. This equation makes use of the byproduct of the Muskat-type equation ((dS_w)/dP) which can be modified in terms of rock and fluid properties to aid in history matching. Furthermore, three well specifications were investigated (constant well pressure, constant drawdown, and constant water production rate) with only two of the three producing a peak rate no peak gas production rate was observed for water rate specified wells. This study also showed that material balance can be used to replace decline curve analysis under certain conditions. This is mainly due to the reduced time to pseudo-steady state (t_pss) caused by the low total compressibility (rock and water), high permeability, low water viscosity, and low drainage area. At a threshold of t_pss less than 0.178 days, an accurate late-time forecast can be attained.Since the proposed semi-analytical model provided water saturation values for different pressures, a non-iterative methodology has been developed to improve upon Kings (G. R. King, 1993) iterative integral material balance equation for unconventional reservoirs.Through this study, a number of significant observations were made. It was found that at a low rock compressibility, the change in saturation over time can be estimated using the water production profile and initial porosity and water formation volume factor. Also, the saturation of gas can be estimated using the percentage of water produced from the original water in place (OWIP), adjusted for desorption time, at an increasing accuracy as the rock compressibility is decreased. Additionally, the cause of a phenomenon known as dual peaking which occurs in field and simulation data of CBM reservoirs has been identified to be due to the transient-state production.

Download or read book Semi analytical Modelling of Fluid Flow in Unconventional Fractured Reservoirs Including Branch fracture Permeability Field written by Ayon Kumar Das and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing demand for energy and unavailability of new viable energy resources have played a crucial role in the persistent exploitation of unconventional resources through multistage hydraulic fracturing. Currently, standard modelling approaches idealize a fractured media as an interplay of several homogeneous continuum of normal diffusive characteristics. However, evolved branch-fractures generate a space with extreme heterogeneity around primary fracture plane. The precise characterization of these branch-fractures is imperative for well performance analysis along with subdiffusive behaviour of unconventional matrices. This study presents two semi-analytical models that account for the branch-fracture permeability field and subdiffusion. The first model, Induced Branch-fracture Subdiffusive Flow model (SIBFF), accounts for exponential permeability field concept and subdiffusive transport behaviour of matrices. Compared to the earlier analytical models, the SIBFF model accounts for more comprehensive transport mechanisms and medium properties. The other model, Fractal Branch-fracture model, couples fractal porosity/permeability distribution of branch-fracture and subdiffusion to account for more detailed description of stimulated reservoir volume (SRV) and unfractured inner region. The wellbore pressure solution is derived by discretizing the reservoir into several flow regions and imposing both flux and pressure continuity at the interface between contiguous segments. The inclusion of permeability field and fractional flux law introduces important complexities to the mathematical model that are carefully resolved by implementing Bessel functions and Laplace transformation (LT). Finally, the solution is inverted to time domain using Gaver-Wynn-Rho (GWR) algorithm. This study also assessed the applicability of four numerical inversion methods and found GWR method more suitable and predictive. The sensitivity of important model parameters is presented. Results were verified analytically and validated against Niobrara and Eagleford field data. It is shown that the models could be implemented to quantify the efficiency of a stimulation job, to decide on the necessity of re-fracturing a formation and to analyze horizontal well performance with better predictive capability. The proposed models could further be employed to characterize different flow regimes for unconventional reservoirs.

Download or read book Unsteady state Fluid Flow written by E.J. Hoffman and published by Elsevier. This book was released on 1999-07-02 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ubiquitous examples of unsteady-state fluid flow pertain to the production or depletion of oil and gas reservoirs. After introductory information about petroleum-bearing formations and fields, reservoirs, and geologic codes, empirical methods for correlating and predicting unsteady-state behavior are presented. This is followed by a more theoretical presentation based on the classical partial differential equations for flow through porous media.Whereas these equations can be simplified for the flow of (compressible) fluids, and idealized solutions exist in terms of Fourier series for linear flow and Bessel functions for radial flow, the flow of compressible gases requires computer solutions, read approximations. An analysis of computer solutions indicates, fortuitously, that the unsteady-state behavior can be reproduced by steady-state density or pressure profiles at successive times. This will demark draw down and the transition to long-term depletion for reservoirs with closed outer boundaries.As an alternative, unsteady-state flow may be presented in terms of volume and surface integrals, and the methodology is fully developed with examples furnished. Among other things, permeability and reserves can be estimated from well flow tests.The foregoing leads to an examination of boundary conditions and degrees of freedom and raises arguments that the classical partial differential equations of mathematical physics may not be allowable representations. For so-called open petroleum reservoirs where say water-drive exists, the simplifications based on successive steady-state profiles provide a useful means of representation, which is detailed in the form of material balances. Unsteady-State Fluid Flow provides:• empirical and classical methods for correlating and predicting the unsteady-state behavior of petroleum reservoirs• analysis of unsteady-state behavior, both in terms of the classical partial differential equations, and in terms of volume and surface integrals• simplifications based on successive steady-state profiles which permit application to the depletion of both closed reservoirs and open reservoirs, and serves to distinguish drawdown, transition and long-term depletion performance.

Download or read book On Coupled Fluid Flow and Geomechanics Modeling for Unconventional Wells written by Yuzhe Cai and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional resources, such as tight gas, shale gas and shale oil, have become an essential source of energy in North America. Advances in hydraulic fracturing and horizontal completions have made exploration of these reservoirs profitable. My study can be broadly divided into three parts. After the hydraulic fracturing, the fracturing fluid needs to be produced back to the surface and the period is called flowback. After the hydraulic fracturing, the fracturing fluid needs to be produced back to the surface and the period is called flowback. In the first part of the study, a semi-analytical model is developed for the purpose of inverse analysis. A coupled fluid flow and geomechanics flow model is also presented to investigate potential reasons for low flowback recovery. Diagnostic fracture injection tests (DFITs) have been broadly used in unconventional reservoirs to derive properties such as initial formation pressure, formation permeability, and closure pressure. The first focus of the dissertation is utilizing DFITs data to obtain formation permeability, and closure pressure. The obtained properties are very crucial for hydraulic fracturing design. A semi-analytical model is proposed for early flowback, and the model can be used for inverse analysis to determine the properties of the hydraulic fracture. The obtained fracture properties can then be used for long-term reservoir production forecast. The last focus of the dissertation is fracture-hits modeling and analysis. Completion of child wells (or infill wells) has received significant attentions in the last few years as a strategy to increase ultimate recovery from unconventional shale plays specially in shale oil reservoirs. However, fracture driven interferences (FDI) between the child wells and the parent wells have been observed, which harm their ultimate recovery. As a result, the interferences between the parent wells and child wells are modeled. By analyzing the pressure response of the parent wells, the FDI can be mitigated. Throughout the study, both coupled geomechanics and fluid flow numerical models and analytical/semi-analytical models are developed. The numerical models can simulate the development of non-planar fractures and non-uniform fracture closure patterns. The analytical/semi-analytical models can be used for quick inverse analysis for estimating fracture or formation properties.

Download or read book Analytical Investigation of Unconventional Reservoir Performance During Early transient Multi phase Flow Conditions written by Miao Zhang and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional gas resources accounted for more than 50% of total U.S. gas production in 2012 and its contribution is expected to increase to 75% by 2040 (EIA, 2015). In these unconventional gas reservoirs, reservoir and fluid characteristics can be significantly different from those in conventional resources, rendering traditional production data analysis methods inadequate. Those effects include long-time transient periods due to ultra-low permeability, pressure-dependent permeability and exemplified large capillary pressure. Development of reliable analysis methods to successfully capture these complex effects demands the formulation of new solutions to the governing flow equations which consider these complex nonlinearities. It is the interest of this study to develop more rigorous performance models for these types of systems derived from fundamental governing flow equations. This study presents a series of novel and rigorous semi-analytical solutions to the governing partial differential equations applicable to single-phase gas and multiphase flow in unconventional reservoirs. Focusing on early-transient periods, the proposed semi-analytical method utilizes similarity theory to transform the system of nonlinear PDEs to ordinary differential form, which is later solved via shooting method coupled Runge-Kutta numerical integration. The work starts with early-transient single-phase gas flow in linear and radial flow regimes under constant pressure and rate production conditions, followed by its direct extension to multiphase flow system using the black-oil fluid formulation. The application of the proposed multiphase flow solution to actual productionhighlighting producing gas-oil-ratio predictionis also discussed. Additionally, the proposed semi-analytical solution is proven capable of solving the multiphase flow equations under fully compositional fluid formulation. In the last chapter, capillary pressure effectsa multiphase flow effect widely recognized to be significant in unconventional system due to nano-scale pore sizeis studied using the proposed semi-analytical method. Besides studying capillary pressure as an additional pressure drop on fluid flow, the effect of capillary pressure on phase behavior and properties is also analyzed. All the results in this work are validated by matching with finely-gridded commercial numerical simulator.

Download or read book Uncertainty Analysis and Reservoir Modeling written by Y. Zee Ma and published by AAPG. This book was released on 2011-12-20 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rate decline Relations for Unconventional Reservoirs and Development of Parametric Correlations for Estimation of Reservoir Properties written by Yohanes Aklilu Askabe and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-rate analysis and time-rate-pressure analysis methods are available to estimate reserves and study flow performance of wells in unconventional gas reservoirs. However, these tools are often incorrectly used or the analysis can become difficult because of the complex nature of the reservoir system. Conventional methods (e.g., Arps' time-rate relations) are often used incorrectly to estimate reserves from such reservoirs. It was only recently that a serious study was conducted to outline the limitations of these relations and to set guidelines for their correct application. New time-rate relations, particularly the Duong and logistic growth model, were introduced to estimate reserves and forecast production from unconventional reservoirs. These new models are being used with limited understanding of their characteristics and limitations. Moreover, well performance analyses using analytical/semi-analytical solutions (time-rate-pressure) are often complicated from non-uniqueness that arises when estimating well/formation properties. In this work, we present a detailed study of the Duong model and logistic growth model to investigate the behaviors and limitations of these models when analyzing production data from unconventional reservoirs. We consider production data generated from numerical simulation cases and data obtained from unconventional gas reservoirs to study the quality of match to specific flow regimes and compare accuracy of the reserve estimates. We use the power-law exponential model (PLE), which has been shown to model transient, transition and boundary-dominated flow regimes reliably, as a benchmark to study performance of Duong and logistic growth models. Moreover, we use the "continuous EUR" approach to compare these models during reserve estimation. Finally, we develop four new time-rate relations, based on characteristics of the time-rate data on diagnostic plots. Using diagnostic plots we show that the new time-rate relations provide a quality match to the production data across all flow regimes, leading to a reliable reserve estimate. In a preliminary study, we integrated time-rate model parameters with fundamental reservoir properties (i.e., fracture conductivity (Fc) and 30 year EUR (EUR30yr)), by studying 15 numerical simulation cases to yield parametric correlations. We have demonstrated a methodology to integrate time-rate model parameters and reservoir properties. This method avoids the non-uniqueness issues often associated with model-based production data analysis. This study provides theoretical basis for further demonstration of the methodology using field cases. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148425

Download or read book Multiphase Fluid Flow in Porous and Fractured Reservoirs written by Yu-Shu Wu and published by Gulf Professional Publishing. This book was released on 2015-09-23 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiphase Fluid Flow in Porous and Fractured Reservoirs discusses the process of modeling fluid flow in petroleum and natural gas reservoirs, a practice that has become increasingly complex thanks to multiple fractures in horizontal drilling and the discovery of more unconventional reservoirs and resources. The book updates the reservoir engineer of today with the latest developments in reservoir simulation by combining a powerhouse of theory, analytical, and numerical methods to create stronger verification and validation modeling methods, ultimately improving recovery in stagnant and complex reservoirs. Going beyond the standard topics in past literature, coverage includes well treatment, Non-Newtonian fluids and rheological models, multiphase fluid coupled with geomechanics in reservoirs, and modeling applications for unconventional petroleum resources. The book equips today’s reservoir engineer and modeler with the most relevant tools and knowledge to establish and solidify stronger oil and gas recovery. Delivers updates on recent developments in reservoir simulation such as modeling approaches for multiphase flow simulation of fractured media and unconventional reservoirs Explains analytical solutions and approaches as well as applications to modeling verification for today’s reservoir problems, such as evaluating saturation and pressure profiles and recovery factors or displacement efficiency Utilize practical codes and programs featured from online companion website

Download or read book An Introduction to Reservoir Simulation Using MATLAB GNU Octave written by Knut-Andreas Lie and published by Cambridge University Press. This book was released on 2019-08-08 with total page 677 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents numerical methods for reservoir simulation, with efficient implementation and examples using widely-used online open-source code, for researchers, professionals and advanced students. This title is also available as Open Access on Cambridge Core.

Download or read book Unconventional Tight Reservoir Simulation Theory Technology and Practice written by Qiquan Ran and published by Springer Nature. This book was released on 2020-08-14 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically introduces readers to the simulation theory and techniques of multiple media for unconventional tight reservoirs. It summarizes the macro/microscopic heterogeneities; the features of multiscale multiple media; the characteristics of complex fluid properties; the occurrence state of continental tight oil and gas reservoirs in China; and the complex flow characteristics and coupled production mechanism under unconventional development patterns. It also discusses the simulation theory of multiple media for unconventional tight oil and gas reservoirs; mathematic model of flow through discontinuous multiple media; geological modeling of discrete multiscale multiple media; and the simulation of multiscale, multiphase flow regimes and multiple media. In addition to the practical application of simulation and software for unconventional tight oil and gas, it also explores the development trends and prospects of simulation technology. The book is of interest to scientific researchers and technicians engaged in the development of oil and gas reservoirs, and serves as a reference resource for advanced graduate students in fields related to petroleum.

Download or read book Formation Testing written by Wilson C. Chin and published by John Wiley & Sons. This book was released on 2014-02-14 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only book available for the reservoir or petroleum engineer covering formation testing—with algorithms for wireline and LWD reservoir analysis developed for transient pressure, contamination modeling, permeability, and pore pressure prediction. Traditional well logging methods, such as resistivity, acoustic, nuclear, and NMR, provide indirect information relating to fluid and formation properties. However, the "formation tester" offered in wireline and MWD/LWD operations is different. It collects actual downhole fluid samples for surface analysis, and through pressure transient analysis, provides direct measurements for pore pressure, mobility, permeability, and anisotropy. These are vital to real-time drilling safety, geosteering, hydraulic fracturing, and economic analysis. Methods for formation testing analysis, while commercially important and accounting for a substantial part of service company profits, are shrouded in secrecy. Many are poorly constructed, and because details are not available, industry researchers are not able to improve on them. Formation Testing explains conventional models and develops new, more powerful algorithms for early-time analysis. More importantly, it addresses a critical area in sampling related to "time required to pump clean samples," using rigorous multiphase flow techniques. All of the methods are explained in complete detail. Equations are offered for users to incorporate in their own models, but, for those needing immediate answers, convenient, easy-to-use software is available. The lead author is a well-known petrophysicist with hands-on experience at Schlumberger, Halliburton, BP Exploration, and other companies. His work is used commercially at major oil service companies, and important extensions to his formation testing models have been supported by prestigious grants from the U.S. Department of Energy. His latest collaboration with China National Offshore Oil Corporation marks an important turning point, where advanced simulation models and hardware are evolving side-by-side, defining a new generation of formation testing logging instruments. Providing more than formulations and solutions, this book offers a close look at "behind the scenes" formation tester development, as the China National Offshore Oil Corporation opens up its research, engineering, and manufacturing facilities through a collection of never-before-seen photographs, showing how formation testing tools are developed from start to finish.

Download or read book Analytical Modeling of Multi Fractured Horizontal Wells in Heterogeneous Unconventional Reservoirs written by Jie Zeng and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current analytical models for multi-fractured horizontal wells (MFHW) generally neglect reservoir heterogeneity, typical seepage characters of unconventional reservoir, partially penetrating fracture and various fracture damage mechanisms. In this thesis, three linear flow models have been developed to facilitate pressure and rate behavior analysis of shale, tight sand and unconventional reservoir with damaged fractures. These models are validated by comparing with KAPPA Ecrin and are more accurate than previous linear flow models in modeling partially penetrating cases. Field data are analyzed and results prove the reliability of these models. The first model is for heterogeneous shale reservoir with multiple gas transport mechanisms. It subdivides the reservoir into seven parts, namely, two upper/lower regions, two outer regions, two inner regions, and hydraulic fracture region. Fracture interference is simulated by locating a no-flow boundary between two adjacent fractures. The locations of these boundaries are determined based on the boundary's pressure to satisfy the no-flow assumption. Adsorption/desorption, gas slippage and diffusion effects are included for rigorous modeling of flow in shale. Sensitivity analysis results suggest that larger desorption coefficient causes smaller pressure and its derivative as a larger proportion of gas is desorbed in formation and contributes to productivity. The influences of other parameters, such as matrix II permeability, matrix block size, secondary fracture permeability, hydraulic fracture conductivity, and fracture pattern are also discussed. The second model is for heterogeneous tight sand reservoir with threshold pressure gradient (TPG). The linear flow sub-regions are the same as those of the first model. TPG and pressure drop within the horizontal wellbore are included. Simulation results suggest that TPG affects middle-late time behaviors. Greater TPG results in higher pressure drop and accelerates production decline. But this influence is marginal when TPG is small. Effects of other parameters, such as formation permeability, fracture length, conductivity, and wellbore storage are also investigated. The third model is for heterogeneous reservoir with various fracture damage. In this model, the following possible fracture damage situations are discussed: (1) choked fracture damage (2) partially propped fracture, (3) fracturing fluid leak-off damage, (4) dual or multiple damage effects. Simulation results indicate that choked frature damage influences early-mid time performance. Partially propped section within fracture dominates formation linear flow regime. Only severe matrix impairment near fracture face can have noticeable effects on pressure and rate response. A new parameter, skin factor ratio, is applied to describe the relative magnitude of multiple damage mechanisms. Reservoir heterogeneity and fracture damage make the pressure and rate behaviors deviate significantly from undamaged one but one can distinguish major damage mechanisms even in heterogeneous reservoir.

Download or read book A New Semi analytical Streamline Simulator and Its Applications to Modelling Waterflooding Experiments written by Nan Zhang and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book A Systems Description of Flow Through Porous Media written by Jan Dirk Jansen and published by Springer Science & Business Media. This book was released on 2013-05-23 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text forms part of material taught during a course in advanced reservoir simulation at Delft University of Technology over the past 10 years. The contents have also been presented at various short courses for industrial and academic researchers interested in background knowledge needed to perform research in the area of closed-loop reservoir management, also known as smart fields, related to e.g. model-based production optimization, data assimilation (or history matching), model reduction, or upscaling techniques. Each of these topics has connections to system-theoretical concepts. The introductory part of the course, i.e. the systems description of flow through porous media, forms the topic of this brief monograph. The main objective is to present the classic reservoir simulation equations in a notation that facilitates the use of concepts from the systems-and-control literature. Although the theory is limited to the relatively simple situation of horizontal two-phase (oil-water) flow, it covers several typical aspects of porous-media flow. The first chapter gives a brief review of the basic equations to represent single-phase and two-phase flow. It discusses the governing partial-differential equations, their physical interpretation, spatial discretization with finite differences, and the treatment of wells. It contains well-known theory and is primarily meant to form a basis for the next chapter where the equations will be reformulated in terms of systems-and-control notation. The second chapter develops representations in state-space notation of the porous-media flow equations. The systematic use of matrix partitioning to describe the different types of inputs leads to a description in terms of nonlinear ordinary-differential and algebraic equations with (state-dependent) system, input, output and direct-throughput matrices. Other topics include generalized state-space representations, linearization, elimination of prescribed pressures, the tracing of stream lines, lift tables, computational aspects, and the derivation of an energy balance for porous-media flow. The third chapter first treats the analytical solution of linear systems of ordinary differential equations for single-phase flow. Next it moves on to the numerical solution of the two-phase flow equations, covering various aspects like implicit, explicit or mixed (IMPES) time discretizations and associated stability issues, Newton-Raphson iteration, streamline simulation, automatic time-stepping, and other computational aspects. The chapter concludes with simple numerical examples to illustrate these and other aspects such as mobility effects, well-constraint switching, time-stepping statistics, and system-energy accounting. The contents of this brief should be of value to students and researchers interested in the application of systems-and-control concepts to oil and gas reservoir simulation and other applications of subsurface flow simulation such as CO2 storage, geothermal energy, or groundwater remediation.

Download or read book Reservoir Model Design written by Philip Ringrose and published by Springer Nature. This book was released on 2021-06-09 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives practical advice and ready to use tips on the design and construction of subsurface reservoir models. The design elements cover rock architecture, petrophysical property modelling, multi-scale data integration, upscaling and uncertainty analysis. Philip Ringrose and Mark Bentley share their experience, gained from over a hundred reservoir modelling studies in 25 countries covering clastic, carbonate and fractured reservoir types, and for a range of fluid systems – oil, gas and CO2, production and injection, and effects of different mobility ratios. The intimate relationship between geology and fluid flow is explored throughout, showing how the impact of fluid type, displacement mechanism and the subtleties of single- and multi-phase flow combine to influence reservoir model design. The second edition updates the existing sections and adds sections on the following topics: · A new chapter on modelling for CO2 storage · A new chapter on modelling workflows · An extended chapter on fractured reservoir modelling · An extended chapter on multi-scale modelling · An extended chapter on the quantification of uncertainty · A revised section on the future of modelling based on recently published papers by the authors The main audience for this book is the community of applied geoscientists and engineers involved in understanding fluid flow in the subsurface: whether for the extraction of oil or gas or the injection of CO2 or the subsurface storage of energy in general. We will always need to understand how fluids move in the subsurface and we will always require skills to model these quantitatively. The second edition of this reference book therefore aims to highlight the modelling skills developed for the current energy industry which will also be required for the energy transition of the future. The book is aimed at technical-professional practitioners in the energy industry and is also suitable for a range of Master’s level courses in reservoir characterisation, modelling and engineering. • Provides practical advice and guidelines for users of 3D reservoir modelling packages • Gives advice on reservoir model design for the growing world-wide activity in subsurface reservoir modelling • Covers rock modelling, property modelling, upscaling, fluid flow and uncertainty handling • Encompasses clastic, carbonate and fractured reservoirs • Applies to multi-fluid cases and applications: hydrocarbons and CO2, production and storage; rewritten for use in the Energy Transition.