Development Of An Efficient Embedded Discrete Fracture Model For 3d Compositional Reservoir Simulation In Fractured Reservoirs

Naturally fractured reservoirs (NFRs) hold a significant amount of the world's hydrocarbon reserves. Compared to conventional reservoirs, NFRs exhibit a higher degree of heterogeneity and complexity created by fractures. The importance of fractures in production of oil and gas is not limited to naturally fractured reservoirs. The economic exploitation of unconventional reservoirs, which is increasingly a major source of short- and long-term energy in the United States, hinges in part on effective stimulation of low-permeability rock through multi-stage hydraulic fracturing of horizontal wells. Accurate modeling and simulation of fractured media is still challenging owing to permeability anisotropies and contrasts. Non-physical abstractions inherent in conventional dual porosity and dual permeability models make these methods inadequate for solving different fluid-flow problems in fractured reservoirs. Also, recent approaches for discrete fracture modeling may require large computational times and hence the oil industry has not widely used such approaches, even though they give more accurate representations of fractured reservoirs than dual continuum models. We developed an embedded discrete fracture model (EDFM) for an in-house fully-implicit compositional reservoir simulator. EDFM borrows the dual-medium concept from conventional dual continuum models and also incorporates the effect of each fracture explicitly. In contrast to dual continuum models, fractures have arbitrary orientations and can be oblique or vertical, honoring the complexity and heterogeneity of a typical fractured reservoir. EDFM employs a structured grid to remediate challenges associated with unstructured gridding required for other discrete fracture models. Also, the EDFM approach can be easily incorporated in existing finite difference reservoir simulators. The accuracy of the EDFM approach was confirmed by comparing the results with analytical solutions and fine-grid, explicit-fracture simulations. Comparison of our results using the EDFM approach with fine-grid simulations showed that accurate results can be achieved using moderate grid refinements. This was further verified in a mesh sensitivity study that the EDFM approach with moderate grid refinement can obtain a converged solution. Hence, EDFM offers a computationally-efficient approach for simulating fluid flow in NFRs. Furthermore, several case studies presented in this study demonstrate the applicability, robustness, and efficiency of the EDFM approach for modeling fluid flow in fractured porous media. Another advantage of EDFM is its extensibility for various applications by incorporating different physics in the model. In order to examine the effect of pressure-dependent fracture properties on production, we incorporated the dynamic behavior of fractures into EDFM by employing empirical fracture deformation models. Our simulations showed that fracture deformation, caused by effective stress changes, substantially affects pressure depletion and hydrocarbon recovery. Based on the examples presented in this study, implementation of fracture geomechanical effects in EDFM did not degrade the computational performance of EDFM. Many unconventional reservoirs comprise well-developed natural fracture networks with multiple orientations and complex hydraulic fracture patterns suggested by microseismic data. We developed a coupled dual continuum and discrete fracture model to efficiently simulate production from these reservoirs. Large-scale hydraulic fractures were modeled explicitly using the EDFM approach and numerous small-scale natural fractures were modeled using a dual continuum approach. The transport parameters for dual continuum modeling of numerous natural fractures were derived by upscaling the EDFM equations. Comparison of the results using the coupled model with that of using the EDFM approach to represent all natural and hydraulic fractures explicitly showed that reasonably accurate results can be obtained at much lower computational cost by using the coupled approach with moderate grid refinements.

The development of naturally fractured reservoirs, especially shale gas and tight oil reservoirs, exploded in recent years due to advanced drilling and fracturing techniques. However, complex fracture geometries such as irregular fracture networks and non-planar fractures are often generated, especially in the presence of natural fractures. Accurate modelling of production from reservoirs with such geometries is challenging. Therefore, Embedded Discrete Fracture Modeling and Application in Reservoir Simulation demonstrates how production from reservoirs with complex fracture geometries can be modelled efficiently and effectively. This volume presents a conventional numerical model to handle simple and complex fractures using local grid refinement (LGR) and unstructured gridding. Moreover, it introduces an Embedded Discrete Fracture Model (EDFM) to efficiently deal with complex fractures by dividing the fractures into segments using matrix cell boundaries and creating non-neighboring connections (NNCs). A basic EDFM approach using Cartesian grids and advanced EDFM approach using Corner point and unstructured grids will be covered. Embedded Discrete Fracture Modeling and Application in Reservoir Simulation is an essential reference for anyone interested in performing reservoir simulation of conventional and unconventional fractured reservoirs. Highlights the current state-of-the-art in reservoir simulation of unconventional reservoirs Offers understanding of the impacts of key reservoir properties and complex fractures on well performance Provides case studies to show how to use the EDFM method for different needs

The simulation of fractured reservoirs is a challenging topic in reservoir simulation owing to the complexity of fracture geometry and recovery processes related to fractured reservoirs. Reliable and efficient numerical models are required for the representation of hydraulic and natural fractures in conventional and unconventional reservoirs. The objective of this work is to develop a numerical approach for simulating complex fractures and complex recovery processes in fractured reservoirs using various types of computational grids. This research is an extension of the Embedded Discrete Fracture Model (EDFM). In this work, methodologies were developed to model various types of 2D and 3D complex fracture geometries. The EDFM was also extended to handle several types of computational grids, including corner-point grids, locally-refined grids, and unstructured grids with mixed elements. Geometrical algorithms were developed and implemented in a general-purpose preprocessing code for the calculation of EDFM connection factors in such grids. The use of the EDFM with matrix grids using various numerical approximation schemes, such as finite-volume method and element-based finite-volume method, was also studied. Furthermore, the model was improved regarding modeling fracture transient flow and dynamic fracture behaviors. For the simulation of hydraulically fractured unconventional reservoirs, various important flow mechanisms were implemented in a compositional simulator. The simulator was used to investigate the relative importance of these mechanisms. The developed methodology was applied to a series of synthetic and realistic case studies. The accuracy of the model was confirmed through comparison with other models for simulating various types of fracture geometries in different hydrocarbon recovery processes. A high computational performance was also achieved using the model. Furthermore, based on the results of this research, for long-term production forecasting, the accuracy of the EDFM is not sensitive to the type of grid, the detailed gridding around fractures, or the numerical approximation scheme, if a similar gridblock size is used in the simulations. For the simulation of short-term flow, the combination of the EDFM with nested grid refinement greatly improves the simulation accuracy for various flow regimes. The modeling of dynamic fracture behaviors and unconventional reservoir flow mechanisms demonstrates the flexibility of the proposed approach in incorporating different physics

Presents advanced reservoir simulation methods used in the widely-used MRST open-source software for researchers, professionals, students.

This book gathers selected papers from the 8th International Field Exploration and Development Conference (IFEDC 2018) and addresses a broad range of topics, including: Reservoir Surveillance and Management, Reservoir Evaluation and Dynamic Description, Reservoir Production Stimulation and EOR, Ultra-Tight Reservoirs, Unconventional Oil and Gas Resources Technology, Oil and Gas Well Production Testing, and Geomechanics. In brief, the papers introduce readers to upstream technologies used in oil & gas development, the main principles of the process, and various related design technologies. The conference not only provided a platform to exchange experiences, but also promoted the advancement of scientific research in oil & gas exploration and production. The book is chiefly intended for industry experts, professors, researchers, senior engineers, and enterprise managers.

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

Fractured reservoirs have gained continuous attention from oil and gas industry. A huge amount of hydrocarbon are trapped in naturally fractured carbonate reservoirs. Besides, the advanced technology of multi-stage hydraulic fracturing have gained a great success in economic development of unconventional oil and gas reservoirs. Fractures add complexity into reservoir flow and significantly impact the ultimate recovery. Therefore, it is important yet challenging to accurately and effectively predict the recovery from fractured reservoirs. Conventional dual-continuum approaches, although effective in the simulation of naturally fractured reservoirs, may fail in some cases due to the highly idealized reservoir model. The unstructured-grid discrete fracture models, although flexible in representing complex fracture geometries, are restricted by the high complexity in gridding and high computational cost. An Embedded Discrete Fracture Model (EDFM) was recently developed to honor the accuracy of discrete fracture models while keeping the efficiency offered by structured gridding. By dividing the fractures into segments using matrix cell boundaries and creating non-neighboring connections (NNCs), the flow influence of fractures can be efficiently modeled through transport indices. In this work, the EDFM was implemented in UTCHEM, a chemical flooding in-house reservoir simulator developed at The University of Texas, to study complex recovery processes in fractured reservoirs. In addition, the model was applied in commercial simulators by making use of the non-intrusive property of the EDFM and the NNC functionality offered by the simulators. The accuracy of the EDFM in the modeling of orthogonal, non-orthogonal, and inclined fractures was verified against fine-grid explicit fracture simulations. Furthermore, case studies were performed to investigate the influence of hydraulic fracture orientations on primary depletion and the impact of large-scale natural fractures on water flooding processes. The influence of matrix grid size and fracture relative permeability was also studied. Finally, with modifications in NNC transmissibility calculation, the EDFM was applied to the modeling of a multi-lateral well stimulation technology. The accuracy of the modified formulations was verified through comparison with a multi-branch well method. The simulations carried out in this work confirmed the flexibility, applicability, and extensiveness of the EDFM.

This book presents guidelines for the design, operation and monitoring of CO2 injection in fractured carbonates, with low permeability in the rock matrix, for geological storage in permanent trapping. CO2 migration is dominated by fractures in formations where the hydrodynamic and geochemical effects induced by the injection play a key role influencing the reservoir behavior. CO2 injection in these rocks shows specific characteristics that are different to injection in porous media, as the results from several research studies worldwide reveal. All aspects of a project of this type are discussed in this text, from the drilling to the injection, as well as support works like well logging, laboratory and field tests, modeling, and risk assessment. Examples are provided, lesson learned is detailed, and conclusions are drawn. This work is derived from the experience of international research teams and particularly from that gained during the design, construction and operation of Hontomín Technology Development Plant. Hontomín research pilot is currently the only active onshore injection site in the European Union, operated by Fundación Ciudad de la Energía-CIUDEN F.S.P. and recognized by the European Parliament as a key test facility. The authors provide guidelines and tools to enable readers to find solutions to their problems. The book covers activities relevant to a wide range of practitioners involved in reservoir exploration, modeling, site operation and monitoring. Fluid injection in fractured media shows specific features that are different than injection in porous media, influencing the reservoir behavior and defining conditions for safe and efficient operation. Therefore, this book is also useful to professionals working on oil & gas, hydrogeology and geothermal projects, and in general for those whose work is related to activities using fluid injection in the ground.

Shale Gas and Tight Oil Reservoir Simulation delivers the latest research and applications used to better manage and interpret simulating production from shale gas and tight oil reservoirs. Starting with basic fundamentals, the book then includes real field data that will not only generate reliable reserve estimation, but also predict the effective range of reservoir and fracture properties through multiple history matching solutions. Also included are new insights into the numerical modelling of CO2 injection for enhanced oil recovery in tight oil reservoirs. This information is critical for a better understanding of the impacts of key reservoir properties and complex fractures. Models the well performance of shale gas and tight oil reservoirs with complex fracture geometries Teaches how to perform sensitivity studies, history matching, production forecasts, and economic optimization for shale-gas and tight-oil reservoirs Helps readers investigate data mining techniques, including the introduction of nonparametric smoothing models

This book mainly focuses on the adaptive analysis of damage and fracture in rock, taking into account multiphysical fields coupling (thermal, hydro, mechanical, and chemical fields). This type of coupling is a crucial aspect in practical engineering for e.g. coal mining, oil and gas exploration, and civil engineering. However, understanding the influencing mechanisms and preventing the disasters resulting from damage and fracture evolution in rocks require high-precision and reliable solutions. This book proposes adaptive numerical algorithms and simulation analysis methods that offer significant advantages in terms of accuracy and reliability. It helps readers understand these innovative methods quickly and easily. The content consists of: (1) a finite element algorithm for modeling the continuum damage evolution in rocks, (2) adaptive finite element analysis for continuum damage evolution and determining the wellbore stability of transversely isotropic rock, (3) an adaptive finite element algorithm for damage detection in non-uniform Euler–Bernoulli beams with multiple cracks, using natural frequencies, (4) adaptive finite element–discrete element analysis for determining multistage hydrofracturing in naturally fractured reservoirs, (5) adaptive finite element–discrete element analysis for multistage supercritical CO2 fracturing and microseismic modeling, and (6) an adaptive finite element–discrete element–finite volume algorithm for 3D multiscale propagation of hydraulic fracture networks, taking into account hydro-mechanical coupling. Given its scope, the book offers a valuable reference guide for researchers, postgraduates and undergraduates majoring in engineering mechanics, mining engineering, geotechnical engineering, and geological engineering.